EP4199879A1

EP4199879A1 - Biodegradable microbeads comprising alginate from algae

Info

Publication number: EP4199879A1
Application number: EP21787333.0A
Authority: EP
Inventors: Vesna Jerkovic; Charlotte SAUSSEZ; Madani LEMAIZI; Nicolas Velings
Original assignee: Ceref Asbl
Current assignee: Ceref Asbl
Priority date: 2020-09-30
Filing date: 2021-09-30
Publication date: 2023-06-28
Also published as: WO2022069674A1

Abstract

The present invention provides exfoliating compositions comprising biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae. The present invention further provides biodegradable gel-microbeads comprising multivalent cation crosslinked alginate from algae, preferably wherein the gel-microbead further comprises at least one carbohydrate of algae different from alginate, and methods for preparing such biodegradable gel-microbeads.

Description

BIODEGRADABLE MICROBEADS COMPRISING ALGINATE FROM ALGAE

FIELD OF THE INVENTION

The present invention relates to the field of biodegradable microbeads. More specifically, the present invention relates to biodegradable microbeads used in cosmetic applications, such as exfoliating compositions. The present invention further relates to exfoliating compositions comprising such biodegradable microbeads and processes to obtain them.

BACKGROUND OF THE INVENTION

Mi croplastics, also known as plastic mi crobeads, are small, often m i croscopi c parti cles of plastic which make their way into our environment regularly via cosmetics, such as exfoliating facial and body washes. Nearly 8000 billion microbeads are dumped daily into the ocean. 663 marine animal species have been identified as negatively impacted by the arrival of these microspheres in the oceans, for example, as a result of marine animals not being able to distinguish between microbeads and food. Furthermore, these microbeads can act as "sponges" capturing harmful chemicals such as pesticides.

As a result thereof, the regulations around plastic microbeads have become more and more strict worldwide. The European Union, as well as several other countries, even decided to ban plastic microbeads due to their detrimental effect on the environment.

Several natural substitutes have been developed, such as microbeads from bamboo silica, microcrystalline cellulose from wood or plants, stones etc. However, some natural substitutes currently available on the market also have a negative impact on the environment or in the water treatment. Furthermore, the natural substitutes currently available are not user friendly or lack manufacturing flexibility to offer the necessary size, color and hardness ranges of the sectors.

Therefore, there is a need to develop further and improved alternatives for plastic microbeads.

SUMMARY OF THE INVENTION

Up till now, the alternatives for polluting plastic microbeads offered several drawbacks. Present inventors have developed gel-microbeads based on algae, which are biodegradable, sustainable, and environment friendly. In addition, the biodegradable gel-microbeads of present invention are insoluble and stable in water as well as in oil. As a result thereof, if the biodegradable gel-microbeads of present inventions are used in an emulsion, they do not destabilize the emulsion. The biodegradable gel- microbeads of present invention are more user friendly than currently existing alternatives to plastic beads.

The present inventors found that the microbeads based on algae can be used as an exfoliant in exfoliating compositions and can have beneficial effects on the skin or teeth by their combined mechanical and bioactive activities on the skin. Moreover, the biodegradable gel-microbeads of present invention can be produced at about the same cost as plastic microbeads. In addition, the production of biodegradable gel-microbeads of present invention requires less energy and results in less harmful byproducts. Furthermore, the biodegradable gel-microbeads of present invention can be produced with a variable hardness and size and with low size dispersion.

A first aspect provides an exfoliating composition comprising biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae.

A further aspect provides the use of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae as exfoliant.

A further aspect provides the use of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae, for skin texture refining, wrinkle regression, and/or cleaning teeth.

A further aspect provides a biodegradable gel-microbead comprising multivalent cation crosslinked alginate from algae.

A further aspect provides a method for preparing an exfoliating composition comprising biodegradable gel-microbeads comprising the step of adding to a composition the gel-microbeads as taught herein.

A further aspect provides a method for preparing biodegradable gel-microbeads comprising: reacting algae powder with an acid, thereby obtaining a mixture comprising alginic acid from insoluble salts of alginate in the algae powder; reacting the alginic acid in the mixture into a water-soluble monovalent salt of alginate, preferably sodium alginate; optionally adjusting the pH of the mixture comprising the water-soluble monovalent salt of alginate to a physiological pH; and o generating microdrops of the mixture comprising the water-soluble monovalent salt of alginate; and o contacting said microdrops with a solution comprising di- and/or trivalent cations, thereby obtaining the gel-microbeads; or o contacting the mixture comprising the water-soluble monovalent salt of alginate with a solution comprising di- and/or trivalent cations, thereby obtaining a gel; and o generating gel-microbeads of the gel. A further aspect provides a biodegradable gel-microbead obtainable by the method as taught herein.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Schematic overview of an exemplary method for preparing biodegradable gel-microbeads using ionotropic gelification. (1) Raw material treatments and formulation; (2) microbead formation by ionotropic gelification; and (3) washing and drying of the gel-microbeads.

Figure 2. Decolored gel-microbeads.

Figure 3. Cream comprising a biodegradable gel-microbead comprising multivalent cation crosslinked alginate from algae and at least one carbohydrate of algae different from alginate

Figure 4. A) Biodegradability curve for Ca²⁺ gel-microbeads. B) Biodegradability curve for Ba²⁺ gel- microbeads.

DETAILED DESCRIPTION OF THE INVENTION

Before the present method and devices used in the invention are described, it is to be understood that this invention is not limited to particular methods, components, or devices described as such methods, components, and devices may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any method and material similar or equivalent to those described herein may be used in practice or testing of the present invention, the preferred methods and materials are now described.

In this specification and the appended claims, the singular forms “a”, “an”, “the” include both the singular and the plural, unless the context clearly indicates otherwise.

The terms “comprising”, “comprises” and “comprised of’ as used herein are synonymous with “including”, “includes” or “containing”, “contains”, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. Where this description refers to a product or process which “comprises” specific features, parts or steps, this refers to the possibility that other features, parts or steps may also be present, but may also refer to embodiments which only contain the listed features, parts or steps. The terms “comprising”, “comprises” and “comprised of’ also include the term “consisting of’.

The enumeration of numeric values by means of ranges of figures comprises all values and fractions in these ranges, as well as the cited end points. The terms “about” and “approximately” as used when referring to a measurable value, such as a parameter, an amount, a time period, and the like, is intended to include variations of +/-10% or less, preferably +/-5% or less, more preferably +/-1% or less, and still more preferably +/-0.1% or less, of and from the specified value, in so far as the variations apply to the invention disclosed herein. It should be understood that the value to which the term “about” or “approximately” refers per se has also been disclosed.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Present inventors have developed gel-microbeads based on algae, which are biodegradable, sustainable, and environment friendly. In addition, the biodegradable gel-microbeads of present invention are insoluble and stable in water as well as in oil. As a result thereof, if the biodegradable gel-microbeads of present inventions are used in an emulsion, they do not destabilize the emulsion. The biodegradable gel-microbeads of present invention are more user friendly than currently existing alternatives to plastic beads. For example, they have a better shape compared to crushed pits or fruit shells; are more skinfriendly than micro-particles of bamboo or stone; have a better abrasiveness than rice or silica microparticles; and are more ready to use compared to heavy micro-particles, such as pumice micro-particles, which need to be mixed before use when being incorporated into, for example, an exfoliating composition.

The present inventors found that the microbeads based on algae can be used as an exfoliant in exfoliating compositions and have beneficial effects on the skin or teeth by their combined mechanical and bioactive activities on the skin. Moreover, the biodegradable gel-microbeads of present invention can be produced at about the same cost as plastic microbeads. In addition, the production of biodegradable gel- microbeads of present invention requires less energy and results in less harmful byproducts. Furthermore, the biodegradable gel-microbeads of present invention can be produced with a variable hardness and size and with low size dispersion. A first aspect provides an exfoliating composition comprising biodegradable gel-microbeads, wherein said microbeads comprise alginate from algae.

The term “biodegradable” as used herein refers to the ability of a composition to get disintegrated by the action of micro-organisms, such as bacteria or fungi, in a biological manner while getting assimilated into the natural environment. Preferably, the gel-microbeads as taught herein are biodegradable in water, preferably in salt water, such as in salt water having a salinity’ of about 3.5%. The biodegradability’ of the gel-microbeads as taught herein in salt water allows the gel-microbeads to disintegrate in the sea or ocean, which is the original habitat for some types of algae that can be used for the preparation of the gel-microbeads as taught herein, thereby resulting in a “sea-to-sea”, or “ocean-to-ocean” loop.

In the context of present invention, the term “microbead” or “microparticle” as used herein refers to a small particle, wherein the particle size ranges from about 2.0 pm to about 2000.0 pm. The microbead can have a core-shell structure or can be homogeneous. The microbead as taught herein has a particle size defined by the area-equivalent diameter (ISO 9276-6:2008(E) section 7), also called Equivalent Circle Diameter (“ECD”, ASTM Fl 877-05 Section 11.3.2). The particle size may be determined using a laser granulometer, such as the Mastersizer - Mavern 2000 (Sysmex). The mean ECD of an at random taken, representati ve, population, for example of at least 40 microbeads, is calculated as the average of respective ECDs of each microbead of the at random taken population. The term “gel-microbead” as used herein refers to a small particle of which the shell, the core and/or the entire particle consists essentially of or consist of a gelled or crosslinked polymer matrix, such as multivalent cation crosslinked alginate. The term “gel” as used herein refers to a non-fluid colloidal network or polymer network that is expanded throughout its whole volume by a fluid.

In particular embodiments, the gel-microbead is made of one type of material and does not comprise a core/shell structure. Accordingly, in particular embodiments, the gel-microbead is homogenous.

In particular embodiments, the biodegradable gel-microbeads are visible, preferably individually distinguishable, with the naked eye within the exfoliating composition.

In particular embodiments, the biodegradable gel-microbeads are intact within the exfoliating composition, meaning that the gel-microbeads retain for at least 90%, preferably for at least 95%, its original shape during, for instance, the handling, the mixing, of the gel-microbeads. In particular embodiments, at least 90%, preferably for at least 95%, of (whole intact) gel-microbeads can be recovered from the exfoliating composition. For example, at least 90%, preferably at least 95%, of gel- microbeads of an at random taken population of at least 40 gel-microbeads are intact within the exfoliating composition and/or can be recovered from the exfoliating composition.

In particular embodiments, the gel-microbeads are homogeneously distributed within the exfoliating composition. In particular embodiments, the gel-microbeads have a homogeneous size distribution with a standard deviation normalized on average of an at random taken population of at least 40 beads lower than 30 %, lower than 25 %, lower than 20 %, lower than 15 %, lower than 10 %, such as lower than 9%, lower than 8 %, lower than 7 %, lower than 6 % or, lower than 5%, such as lower than 4 % , lower than 3%, lower than 2 % or lower than 1 %, preferably lower than 25 %. Said homogeneous size distribution improves the distribution of said gel-microbeads into the exfoliating composition.

In particular embodiments, the gel-microbeads have a mean ECD from 2.0 pm to 2000.0 pm, from 2.0 pm to 1500.0 pm, from 2.0 pm to 1000.0 pm, from 10.0 pm to 1000.0 pm, from 50.0 pm to 1000.0 pm, from 100.0 pm to 1000.0 pm such as for example a mean ECD of about 100.0 pm, about 200.0 pm, about 300.0 pm, about 400.0 pm, about 500.0 pm, about 600.0 pm, about 700.0 pm, about 800.0 pm, about 900.0 pm, about 1000.0 pm, from 150.0 pm to 1000.0 pm, from 200.0 pm to 1000.0 pm, from 200.0 pm to 750.0 pm, from 250.0 pm to 750.0 pm, from 250.0 pm to 500.0 pm, from 300.0 pm to 500.0 pm, or from 200.0 pm to 800.0 pm, preferably from 200.0 pm to 800.0 pm, from 200.0 pm to 750.0 pm, from 250.0 pm to 750.0 pm, from 250.0 pm to 500.0 pm, or from 300.0 pm to 500.0 pm, more preferably from 300.0 pm to 500.0 pm. The mean ECD of an at random taken, representative, population, for example of at least 40 gel-microbeads, is calculated as the average of respective ECDs of each gel-microbead of the at random taken population.

The term “exfoliating composition” as used herein refers to a composition comprising one or more mechanical (e.g. microbeads) and/or chemical means (e.g. salicylic acid, glucolic acid, fruit enzymes, citric acid or malic acid) suitable for removing undesired substances from a surface (such as removing dead skin cells from the skin surface or removing surface stains from teeth), also known as mechanical and/or chemical exfoliants. Non-limiting examples of exfoliating compositions include skin cleansing compositions (e.g. face mask, face cleanser, face cream, body lotion, body wash, facial wash), exfoliating shower gels, exfoliating hair care compositions (e.g. shampoo, hair mask) and body (including the face), shaving cream, feet scrub or peel compositions or toothpaste. In particular embodiments, the exfoliating composition is a skin cleansing composition, an exfoliating shower gel, an exfoliating hair care composition, a body or feet scrub composition, or a toothpaste.

In particular embodiments, the exfoliating composition comprises from 0. 10 to 30.0 % (w/w), from 0.10 to 20.0 % (w/w), from 0.50 to 20.0 % (w/w), from 0.10 to 15.0 % (w/w), from 0.50 to 15.0 % (w/w), from 1.0 to 15.0 % (w/w), from 5.0 to 15.0 % (w/w), or from 10.0 to 15.0 % (w/w), preferably from 0.10 to 15.0 % (w/w) of said gel-microbeads, based on the weight of the composition.

In particular embodiments, the exfoliating composition comprises at least 0.10 % (w/w), at least 0.20 % (w/w), at least 0.30 % (w/w), at least 0.40 % (w/w), at least 0.50 % (w/w), at least 1.0 % (w/w), or at least 5.0 % (w/w), preferably at least 1 % (w/w) of said gel-microbeads, based on the weight of the composition. In particular embodiments, the exfoliating composition comprises at most 30.0 % (w/w), at most 20.0 % (w/w), at most 15.0 % (w/w), or at most 10.0 % (w/w), preferably at most 15.0 % (w/w), of said gelmicrobeads, based on the weight of the composition.

In particular embodiments, the exfoliating composition is in a liquid, solid or semisolid form.

The person skilled in the art will understand that the exfoliating composition may comprise other adjunct ingredients that may modify the physical, chemical cosmetic or aesthetic characteristics of the composition or serve as additional active ingredients when deposited on the skin.

In particular embodiments, the exfoliating composition comprises one or more cosmetically acceptable additives selected from the group consisting of essential oil, antioxidant, emulsifier, preservative, vitamin, fragrance, colouring and a combination thereof.

Mechanical exfoliants physically remove cells from the skin surface. Furthermore, mechanical exfoliants refine the texture of the skin and stimulate cell renewal . Mechanical exfoliants also benefit skin by preparing it for subsequent moisturizing treatments. The biodegradable gel-microbeads as taught herein are mild and gentle to the skin, while allowing a good exfoliation of the skin.

Accordingly, a further aspect provides the use of biodegradable gel-microbeads, wherein said gel- microbeads comprise alginate from algae, as an exfoliant.

A further aspect provides a method for exfoliating skin comprising applying biodegradable gel- microbeads comprising alginate from algae to the skin.

In particular embodiments, the method for exfoliating skin further comprises a step of rubbing said skin after application of said biodegradable gel-microbeads and optionally a step of rinsing said skin.

The outer layer of the skin consists of dead skin cells. The skin naturally sheds dead skin cells through a process called desquamation. When desquamation does not take place regularly, the surface of the skin tends to become rougher and more wrinkles and other undesirable effects appear on the surface of the skin. Present inventors found that the gel-microbeads comprising alginate from algae as taught herein not only exert beneficial effects on the skin by their mechanical activities on the skin, but also by their bioactive activities. More particularly, in addition to their potential ability to mechanically remove dead skin cells from the skin surface, the variety of types of algae components within the microbeads can exert beneficial bioactive effects (e.g. anti-oxidant, anti-melanogenic, anti -aging effects, hydrating/moisturizing, skin-firming, protection of skin from photo-aging, anti-wrinkle, improvement of skin barrier function, remineralization, draining properties, antiseptic properties, skin regeneration skin emolliating, skin-soothing properties, anti-blackheads properties, anti-pollution properties and film-forming properties, preferably anti-aging effects, skin-soothing properties, anti-blackheads properties, and anti-pollution properties) on the skin thereby contributing to the overall skin beauty. Accordingly, a further aspect provides the use, preferably a cosmetic use, of biodegradable gelmicrobeads, wherein said gel-microbeads comprise alginate from algae, for skin texture refining, wrinkle regression, and/or for cleaning teeth.

Also provided herein is a method for refining skin texture, regressing wrinkles, and/or cleaning teeth comprising applying biodegradable gel-microbeads comprising alginate from algae to the skin.

In particular embodiments, the method for refining skin texture and/or regressing wrinkles further comprises a step of rubbing said skin after application of said biodegradable gel-microbeads and optionally a step of rinsing said skin.

In particular embodiments, the method for cleaning teeth further comprises a step of rubbing said teeth after application of said biodegradable gel-microbeads and optionally a step of rinsing said teeth.

Also provided herein is the use, preferably a cosmetic use, of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae, for skin rejuvenation, for improving the general appearance of the skin, for improving skin smoothness, for unclogging pores, for skin hydration, for skin plumping, for inducing a skin-glow and/or for evening skin tone.

Also provided herein is a method for rejuvenating skin, improving the general appearance of the skin, improving skin smoothness, unclogging pores, hydrating skin, plumping skin, inducing a skin-glow and/or for evening skin tone comprising applying biodegradable gel-microbeads comprising alginate from algae to the skin.

In particular embodiments, the method for rejuvenating skin, improving the general appearance of the skin, improving skin smoothness, unclogging pores, hydrating skin, plumping skin, inducing a skinglow and/or for evening skin tone further comprises a step of rubbing said skin after application of said biodegradable gel-microbeads and optionally a step of rinsing said skin.

In particular embodiments, the method for exfoliating skin further comprises a step of rubbing said skin after application of said biodegradable gel-microbeads and optionally rinsing said skin.

Also provided herein is the use, preferably a cosmetic use, of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae, as an alternative for the natural desquamation process.

Also provided herein is a method for cleaning teeth or for removing surface stains from the teeth comprising applying biodegradable gel-microbeads comprising alginate from algae to the teeth.

A further aspect provides a biodegradable gel-microbead comprising, consisting essentially of, or consisting of multivalent cation crosslinked alginate from algae. In particular embodiments, said biodegradable gel-microbead further comprises at least one carbohydrate of algae different from alginate, preferably at least one carbohydrate of the cell wall of algae different from alginate.

The term “alginate” as used herein may refer to any salt of alginic acid, including, but not limited to sodium alginate, calcium alginate, magnesium alginate and potassium alginate. The phrase “alginate from algae” as used herein refers to the alginic acid being extracted from algae, for example, by ion exchange.

In particular embodiments, the alginate is multivalent cation crosslinked alginate.

The term “cation” as used herein may be any cation suitable for inducing the gelling of alginate when added to the ingredient mixture or solution. Cations are preferably divalent or trivalent cations, preferably cosmetic grade divalent or trivalent cations.

In particular embodiments, the multivalent cation is a di- and/or trivalent cation, preferably a di- and/or trivalent cation selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof, preferably Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

In particular embodiments, the alginate is selected from the group consisting of calcium alginate, iron(II) alginate (Fe(II)-alginate), iron (III) alginate (Fe(III)-alginate), zinc alginate (Zn-alginate), manganese alginate (Mn-alginate), barium alginate (Ba-alginate), copper alginate (Cu-alginate), aluminium (Al- alginate), strontium alginate (Sr-alginate); preferably the alginate is calcium alginate. The person in the art will understand that “iron(II) alginate” refers to iron-crosslinked alginate and that the same applies for all other alginate salts described herein.

The term “algae” as used herein refers to photosynthetic eukaryotic organisms living in moist environments and include marine algae (e.g. seaweeds), freshwater algae and brackish water algae.

In particular embodiments, the algae are marine algae. In particular embodiments, the algae are multicellular algae.

In particular embodiments, the algae are brown algae (i.e. Phaeophyceae) . In particular embodiments, the algae are algae of a genus selected from the group consisting of Laminaria, Himanthalia, Fucus, Undaria, Macroocystis, Ecklonia, Lessonia, Durvillaea, Sargassum and any combination thereof, preferably Laminaria.

In particular embodiments, the algae are algae having an alginate content of at least 10.0 % (w/w), at least 20.0 % (w/w), at least 25.0 % (w/w), such as at least 26.0 % (w/w), at least 27.0 % (w/w), at least 28.0 % (w/w), or at least 29.0 % (w/w), at least 30.0 % (w/w), at least 35.0 % (w/w), or at least 40.0 % (w/w), preferably at least 20.0% (w/w), based on total biomass dry weight. In particular embodiments, the algae are algae having an alginate content of from 10.0 % (w/w) to 45.0% (w/w), from 15.0% (w/w) to 40.0% (w/w), from 20.0% (w/w) to 40.0% (w/w), from 30.0% (w/w) to 40.0% (w/w), from 15.0% (w/w) to 30.0% (w/w), from 20.0% (w/w) to 30.0% (w/w), preferably from 20.0% (w/w) to 30.0% (w/w), based on total biomass dry weight. Non-limiting examples of algae having an alginate content of at least 20.0 % (w/w) based on total biomass dry weight, include algae of the species Laminaria Hyperborea, Laminaria Digitata Ascophyllum nodosum, Laminaria saccharina, Himanthalia elongate, Laminaria ochroleuca, Fucus vesiculosus, Undaria pinnatifida, Macrocystis pyrifera, Laminaria japonica, Ecklonia maxima, Lessonia nigrescens, Durvillaea antartica or Sargassum spp. The person skilled in the art will understand that the alginate content of algae may depend on the conditions in which they are grown, such as the season, growth conditions, location and deepness.

In particular embodiments, the amount of alginate in the algae (i.e. endogenous alginate) is sufficient to allow the preparation of gel-microbeads from whole algae powder with a good stability and hardness. In particular embodiments, the whole algae powder is not enriched with exogenous alginate.

In particular embodiments, the algae are algae selected from the group consisting of Laminaria hyperborea, Laminaria digitata, Ascophyllum nodosum, Laminaria saccharina, Himanthalia elongate, Laminaria ochroleuca, Fucus vesiculosus, Undaria pinnatifida, Macrocystis pyrifera, Laminaria japonica, Ecklonia maxima, Lessonia nigrescens, Durvillaea antartica, Sargassum spp and any combination thereof. These algae are available in Europe in large quantities, have a limited use in food industry and do not require a harvest method destructive for biodiversity.

In particular embodiments, the algae are algae of the family Laminariaceae. In particular embodiments, the algae are algae of the genus Laminaria. In particular embodiments, the algae are algae of the species Laminaria Hyperborea, Laminaria Digitata, or a combination thereof.

In particular embodiments, the gel-microbead as taught herein comprises at least one, such as at least two, at least three, at least four, at least five, at least six, at least seven, at least 8 or at least 9, preferably at least two, more preferably at least three, carbohydrates of algae different from alginate.

In particular embodiments, the gel-microbead as taught herein comprises at least one carbohydrate of algae different from alginate. Non-limiting examples of carbohydrates of algae different from alginate include cellulose, hemicellulose (e.g. xylan), ulvan, mannan, glycan, galactan (e.g. agar and carrageenan), fucoidan, laminarin and mannitol. In particular embodiments, the gel-microbead as taught herein further comprises at least one carbohydrate of algae different from alginate selected from the group consisting of cellulose, hemicellulose, carrageenan, agar, ulvan, fucoidan, laminarin, mannitol, and combinations thereof, preferably at least one carbohydrate of algae selected from the group consisting of cellulose, carrageenan, agar and a combination thereof.

In particular embodiments, the gel-microbead as taught herein further comprises at least one carbohydrate (such as one, two, three, four, five, six or seven), preferably a structural carbohydrate, more preferably a structural polysaccharide, of the cell wall of algae different from alginate. Non-limiting examples of cell wall components of algae that are carbohydrates include cellulose, hemicellulose (e.g. xylan), ulvan, mannan, glycan, galactan (e.g. agar and carrageenan) and fucoidan.

In particular embodiments, the gel-microbead as taught herein comprises at least one storage carbohydrate, preferably a storage polysaccharide, of algae, more preferably laminarin, mannitol or a combination thereof.

In particular embodiments, the gel-microbead as taught herein comprises at least one carbohydrate of algae different from alginate, preferably at least one carbohydrate of the cell wall of algae different from alginate, which is not soluble in an acidic solution (e.g. a H2SO4 solution), or a monovalent salt solution, preferably not soluble in a sodium, potassium, or sodium potassium salt solution, more preferably not soluble in a sodium carbonate solution, even more preferably not soluble in a 0.2N H2SO4 solution or in a 2 % (w/v) Na2CC>3.

In particular embodiments, the gel-microbead as taught herein further comprises at least one structural carbohydrate, more preferably a structural polysaccharide, of the cell wall of algae different from alginate which is not soluble in an acidic solution (e.g. a H2SO4 solution), or a monovalent salt solution, preferably not soluble in a sodium, potassium, or sodium potassium salt solution, more preferably not soluble in a sodium carbonate solution, even more preferably not soluble in a 0.2N H2SO4 solution or in a 2 % (w/v) Na2CC>3.

In particular embodiments, the gel-microbead as taught herein further comprises at least one structural carbohydrate, preferably at least one structural polysaccharide, from the cell wall of algae selected from the group consisting of cellulose, hemicellulose, carrageenan, agar, ulvan, fucoidan, and a combination thereof, preferably at least one structural polysaccharide from the cell wall of algae selected from the group consisting of cellulose, carrageenan, agar and a combination thereof.

In particular embodiments, the alginate and the at least one, such as at least two, at least three, at least four, at least five, at least six, at least seven, at least 8 or at least 9, preferably at least two, more preferably at least three, carbohydrates of algae different from alginate are present in the gel of the gel-microbead in substantially the same ratios as they occur in the algae, preferably in the cell wall of algae, from which they are prepared. For example, and purely hypothetically, if the cell wall of algae would comprise 1% (w/w) of carrageenan and 2% (w/w) of cellulose, the gel-microbead of present invention would comprise twice as much cellulose than carrageenan.

In particular embodiments, the gel-microbead as taught herein comprises at least 15.0 % (w/w), at least 20.0 % (w/w), at least 25.0 % (w/w), at least 30.0 % (w/w), at least 35.0 % (w/w), at least 40.0 % (w/w), at least 45.0 % (w/w), or at least 50.0 % (w/w), of alginate, based on the dry weight of the gel-microbead.

In particular embodiments, the gel-microbead as taught herein comprises from 15.0 % (w/w) to 99.0 % (w/w), from 15.0 % (w/w) to 95.0 % (w/w), from 20.0 % (w/w) to 90.0 % (w/w), from 25.0 % (w/w) to 80.0 % (w/w), from 30.0 % (w/w) to 80.0 % (w/w), from 35.0 % (w/w) to 60.0 % (w/w), or from 40.0 % (w/w) to 50.0 % (w/w) of alginate, based on the dry weight of the gel-microbead.

In particular embodiments, the gel-microbead as taught herein comprises at least 1.0 % (w/w), such as at least 2.0 % (w/w), at least 3.0 % (w/w), at least 4.0 % (w/w), or at least 5.0 % (w/w), at least 10.0 % (w/w), at least 15.0 % (w/w), at least 20.0 % (w/w), at least 25.0 % (w/w), at least 30.0 % (w/w), at least 35.0 % (w/w), at least 40.0 % (w/w), at least 45.0 % (w/w), or at least 50.0 % (w/w), preferably at least 5.0 % (w/w), more preferably at least 10.0 % (w/w) of at least one carbohydrate of algae different from alginate, preferably at least one carbohydrate of the cell wall of algae different from alginate, based on the dry weight of the gel-microbead.

In particular embodiments, the gel-microbead as taught herein comprises at least 70.0 % (w/w), at least 75.0 % (w/w), at least 80.0 % (w/w), at least 85.0 % (w/w), at least 90.0 % (w/w), at least 95.0 % (w/w), such as at least 96.0 % (w/w), at least 97.0 % (w/w), at least 98.0 % (w/w) or at least 99.0 % (w/w), of components from algae, based on the dry weight of the gel-microbead. In particular embodiments, the gel-microbead as taught herein comprises from 70.0 % (w/w) to 85.0 % (w/w), such as from 75.0 % (w/w) to 85.0 % (w/w), or from 80.0 % (w/w) to 85.0 % (w/w), of components from algae, based on the dry weight of the gel-microbead. The components (e.g. the alginate) from algae within the gel- microbead as taught herein are preferably chemically treated (e.g. extracted from the algae) before being incorporated into the gel-microbead.

In particular embodiments, the gel-microbead as taught herein comprises at least 70.0 % (w/w), at least 75.0 % (w/w), at least 80.0 % (w/w), at least 85.0 % (w/w), at least 90.0 % (w/w), at least 95.0 % (w/w), such as at least 96.0 % (w/w), at least 97.0 % (w/w), at least 98.0 % (w/w) or at least 99.0 % (w/w), of alginate and at least one carbohydrate different from alginate, based on the dry weight of the gel- microbead. In particular embodiments, the gel-microbead as taught herein comprises from 70.0 % (w/w) to 85.0 % (w/w), such as from75.0 % (w/w) to 85.0 % (w/w), or from 80.0 % (w/w) to 85.0 % (w/w), of alginate and at least one carbohydrate different from alginate, based on the dry weight of the gel- microbead.

In particular embodiments, the gel-microbead as taught herein comprises at least 70.0 % (w/w), at least 75.0 % (w/w), at least 80.0 % (w/w), at least 85.0 % (w/w), at least 90.0 % (w/w), at least 95.0 % (w/w), such as at least 96.0 % (w/w), at least 97.0 % (w/w), at least 98.0 % (w/w) or at least 99.0 % (w/w), of carbohydrates of algae (i.e. including alginate), based on the dry weight of the gel-microbead. In particular embodiments, the gel-microbead as taught herein comprises from 70.0 % (w/w) to 85.0 % (w/w), such as from75.0 % (w/w) to 85.0 % (w/w), or from 80.0 % (w/w) to 85.0 % (w/w), of carbohydrates of algae (i.e. including alginate), based on the dry weight of the gel-microbead. In particular embodiments, the biodegradable gel-microbead as taught herein is prepared starting from whole algae powder. In particular embodiments, the algae are decoloured prior to grinding the algae into a whole algae powder or the whole algae powder is decoloured.

In particular embodiments, the biodegradable gel-microbead has a particle size of from 2.0 pm to 2000.0 pm, from 2.0 pm to 1500.0 pm, from 2.0 pm to 1000.0 pm, from 10.0 pm to 1000.0 pm, from 50.0 pm to 1000.0 pm, from 100.0 pm to 1000.0 pm, from 150.0 pm to 1000.0 pm, from 200.0 pm to 1000.0 pm, from 200.0 pm to 750.0 pm, from 250.0 pm to 750.0 pm, from 250.0 pm to 500.0 pm, from 300.0 pm to 500.0 pm, or from 200.0 pm to 800.0 pm, preferably from 200.0 pm to 800.0 pm, from 200.0 pm to 750.0 pm, from 250.0 pm to 750.0 pm, from 250.0 pm to 500.0 pm, or from 300.0 pm to 500.0 pm, more preferably from 300.0 pm to 500.0 pm. The gel-microbead as taught herein has a particle size defined by the area-equivalent diameter (ISO 9276-6:2008(E) section 7), also called Equivalent Circle Diameter (“ECD”, ASTM Fl 77-05 Section 1 1.3.2).

In particular embodiments, the biodegradable gel-microbeads (e.g. an at random taken, representative, population, for example of at least 40 microbeads) have a mean ECD from 2.0 pm to 2000.0 pm, from 2.0 pm to 1500.0 pm, from 2.0 pm to 1000.0 pm, from 10.0 pm to 1000.0 pm, from 50.0 pm to 1000.0 pm, from 100.0 pm to 1000.0 pm, from 150.0 pm to 1000.0 pm, from 200.0 pm to 1000.0 pm, from 200.0 pm to 750.0 pm, from 250.0 pm to 750.0 pm, from 250.0 pm to 500.0 pm, from 300.0 pm to 500.0 pm, or from 200.0 pm to 800.0 pm, preferably from 200.0 pm to 800.0 pm, from 200.0 pm to 750.0 pm, from 250.0 pm to 750.0 pm, from 250.0 pm to 500.0 pm, or from 300.0 pm to 500.0 pm, more preferably from 300.0 pm to 500.0 pm.

In particular embodiments, if the biodegradable gel-microbead is intended for use as an exfoliant or in an exfoliating composition for the face, the biodegradable gel-microbead preferably has a particle size of from 2.0 pm to 300.0 pm, from 25.0 pm to 300.0 pm, from 50.0 pm to 300.0 pm, from 100.0 pm to 300.0 pm, from 200.0 pm to 300.0 pm, from 50.0 pm to 200.0 pm, or from 100.0 pm to 200.0 pm, preferably from 200.0 pm to 300.0 pm. In particular embodiments, if the biodegradable gel-microbeads are intended for use as an exfoliant or in an exfoliating composition for the face, the biodegradable gel- microbeads (e.g. an at random taken, representative, population, for example of at least 40 microbeads) preferably have a mean ECD from 2.0 pm to 300.0 pm, from 25.0 pm to 300.0 pm, from 50.0 pm to 300.0 pm, from 100.0 pm to 300.0 pm, from 200.0 pm to 300.0 pm, from 50.0 pm to 200.0 pm, or from 100.0 pm to 200.0 pm.

In particular embodiments, if the biodegradable gel-microbead is intended for use as an exfoliant or in an exfoliating composition for the body, the biodegradable gel-microbead preferably has a particle size of from 300.0 pm to 500.0 pm, from 350.0 pm to 500.0 pm, from 400.0 pm to 500.0 pm, from 300.0 pm to 400.0 pm, or from 350.0 pm to 450.0 pm. In particular embodiments, if the biodegradable gel- microbeads are intended for use as an exfoliant or in an exfoliating composition for the body, the biodegradable gel-microbeads (e.g. an at random taken, representative, population, for example of at least 40 microbeads) preferably have a mean ECD from 300.0 pm to 500.0 pm, from 350.0 pm to 500.0 pm, from 400.0 pm to 500.0 pm, from 300.0 pm to 400.0 pm, or from 350.0 pm to 450.0 pm.

In particular embodiments, if the biodegradable gel-microbead is intended for use as an exfoliant or in an exfoliating composition wherein the gel-microbead has to be individually distinguishable by eye within the exfoliating composition, the biodegradable gel-microbead preferably has a particle size of from 500.0 pm to 2000.0 pm, from 500.0 pm to 1500.0 pm, from 500.0 pm to 1000.0 pm, from 600.0 pm to 1000.0 pm, from 700.0 pm to 1000.0 pm, from 800.0 pm to 1000.0 pm, or from 900.0 pm to 1000.0 pm. In particular embodiments, if the biodegradable gel-microbeads are intended for use as an exfoliant or in an exfoliating composition wherein the gel-microbeads have to be individually distinguishable by eye within the exfoliating composition, the biodegradable gel-microbeads (e.g. an at random taken, representative, population , for exampl e of at least 40 microbeads) preferably have a mean ECD from 400.0 pm to 2000.0 pm, from 400.0 pm to 1500.0 pm, from 400.0 pm to 1000.0 pm, from 500.0 pm to 1000.0 pm, from 600.0 pm to 1000.0 pm, from 700.0 pm to 1000.0 pm, from 800.0 pm to 1000.0 pm, or from 900.0 pm to 1000.0 pm.

In particular embodiments, if the biodegradable gel-microbead is intended for use as an exfoliant or in an exfoliating composition for teeth, the biodegradable gel-microbead preferably has a particle size of from 50.0 pm to 400.0 pm, from 500.0 pm to 2000.0 pm, from 500.0 pm to 1500.0 pm, from 500.0 pm to 1000.0 pm, from 600.0 pm to 1000.0 pm, from 700.0 pm to 1000.0 pm, from 800.0 pm to 1000.0 pm, or from 900.0 pm to 1000.0 pm. In particular embodiments, if the biodegradable gel-microbeads are intended for use as an exfoliant or in an exfoliating composition for teeth, the biodegradable gel- microbeads (e.g. an at random taken, representative, population, for example of at least 40 microbeads) preferably have a mean ECD from 400.0 pm to 2000.0 pm, from 400.0 pm to 1500.0 pm, from 400.0 pm to 1000.0 pm, from 500.0 pm to 1000.0 pm, from 600.0 pm to 1000.0 pm, from 700.0 pm to 1000.0 pm, from 800.0 pm to 1000.0 pm, or from 900.0 pm to 1000.0 pm.

In particular embodiments, the biodegradable beads as taught herein have a symmetric and regular particle shape such as cubic beads, spherical beads, cylindrical beads, preferably spherical beads.

The present inventors found that biodegradable gel-microbeads comprising multivalent cation crosslinked alginate from algae and at least one component of the cell wall of algae different from alginate can have a wide variety of hardness, making them suitable for a wide range of applications.

If the biodegradable gel-microbead as taught herein is used as an exfoliant, the microbead is preferably sufficiently hard to provide good cleansing performance while providing good skin or tooth feel acceptability. In particular embodiments, the biodegradable gel-microbead has a hardness that is typically used for exfoliants. The person skilled in the art will understand how to determine the hardness of a microbead, such as by nano-identation. For example, the biodegradable gel-microbead has a hardness that corresponds to a MOHS hardness from 0.50 to 6.0, from 0.50 to 5.0, from 0.50 to 4.0, from 0.50 to 3.0, from 1.0 to 4.0, orfirom 1.0 to 3.0, preferably from 1.0 to 5.0, preferably when measured at room temperature, such as at a temperature from 20.0 to 22.0°C. The MOHS hardness scale is known in the art and is an internationally recognized scale for measuring the hardness of a compound versus a compound of known hardness, such as for example sodium with a MOHS hardness of from 0.5 to 0.6, talc with a MOHS hardness of 1, graphite with a MOHS hardness of 1.5, gypsum with a MOHS hardness of 2, gold with a MOHS hardness of from 2.5 to 3, calcite with a MOHS hardness of 3, platinum with a MOHS hardness of 3.5 and fluorite with a MOHS hardness of 4.

In particular embodiments, the gel-microbeads as taught herein have a hardness of from 30.0 to 300.0 MPa, from 30.0 to 250.0 MPa, from 30.0 to 200.0 MPa, from 35.0 to 175.0 MPa, from 35.0 to 150.0 MPa, from 35.0 to 145.0 MPa, from 35.0 to 140.0 MPa, from 35.0 to 135.0 MPa or from 35.0 to 130.0 MPa.

Polymer-crosslinking of the alginate from algae and optional at least one cell wall component obtained from algae different from alginate, may be achieved by any method known in the art, such as iontropic gelification, coarcervation, interfacial polymerization, spray drying, atomisation, solvent evaporation, coating, prilling, sonication or extrusion. The person skilled in the art will understand that depending on the type of the at least one component of the cell wall of algae different from alginate, the at least one cell wall component obtained from algae different from alginate may be cross-linked itself, such as for cellulose, or may become dispersed in the gel formed by the alginate.

In particular embodiments, the biodegradable gel-microbead is prepared by ionotropic gelification, optionally in combination with jet-cutting.

The term “ionotropic gelification” as used herein refers to a commonly used method to produce micro- or nanoparticles which is based on the capability of polyelectrolytes to traverse link in the presence of counter ions. Ionotropic gelification may be achieved by any method known in the art. For example, as applied in the present context, by extruding or spraying an alginate solution into a solution comprising multivalent cations.

The term “jet-cutting” as used herein refers to a method in which a flow of ingredients is cut with the aid of a cutting device, such as rotating wires.

An example of a suitable cutting system may be described in the following way: a cutting tool with a diameter of 70 mm and having at its circumference 24 to 48 strings of stainless-steel cable with a diameter of 90 pm to 200 pm is attached to the shaft of a motor; nozzles with an internal diameter of from 100 pm to 1200 pm, preferably from 200 pm to 800 pm, are positioned just above the cutting device, this can be in a specific angle; the ingredient mixture is passed through the nozzles with a pressure between 10 psi and 120 psi; and; the stator (rotating disk) rotates at a speed between 2000 and 10000 rpm, preferably between 4000 and 8000 rpm.

A skilled person will understand that the jet cutting system parameters (number and size of wires, nozzles diameters, extrusion pressure, stator rotation speed, etc.) may be adjusted to make different sizes and shapes of microbeads.

The final granulometry of the microbeads is close to the diameter of the nozzle of the jet-cutter.

In particular embodiments, the nozzle diameter is from 300.0 to 800.0 pm.

In particular embodiments, the stator rotation speed is between 2000 and 10000 rpm, preferably between 4000 and 8000 rpm.

In particular embodiments, the biodegradable gel-microbead is prepared by spray drying. In spray drying, nebulization and evaporation is typically combined. For example, particle formation, drying, and cross-linking of the alginate may occur in a single step.

The person skilled in the art will understand that the biodegradable gel-microbead as taught herein can be used for a variety of applications, including, but not limited to, chemical applications (e.g. paint, detergent, cleaner), food applications (e.g. dietary supplement, pet feed, gastronomy), cosmetic applications (e.g. personal care, face masks), agronomic applications (e.g. animal feed), and medical application (e.g. controlled release of medicaments).

Accordingly, a further aspect provides the use of the biodegradable gel-microbead as taught herein in chemical applications (e.g. paint, detergent, cleaner), food applications (e.g. dietary supplement, pet feed, gastronomy), cosmetic applications (e.g. face masks, toothpaste) or agronomic applications (e.g. animal feed).

Furthermore, a medicament or bioactive molecule can be trapped between the polymeric chains of the gel-microbead, resulting in being captured inside the gel-microbead structure. Such formulation allows controlled release of the medicament.

Accordingly, a further aspect provides the use of the biodegradable gel-microbead as taught herein as a medicament.

A further aspect provides a method of treating a disease or condition in a subject, comprising administering the biodegradable gel-microbead as taught herein to the subject.

In particular embodiments, the biodegradable gel-microbead as taught herein comprises one or more additi ves selected from the group consi sting of a fragrance and a colorant .

In particular embodiments, the biodegradable gel-microbead as taught herein is cosmetic-grade. In particular embodiments, the biodegradable gel-microbead as taught herein does not comprise any plastic (e.g. polyethylene), fruit shells or pits, bamboo silica, polylactic acid, rice, stones, silica and/or waxes.

In particular embodiments, the biodegradable gel-microbead as taught herein does not comprise chromium, nickel and/or arsenic.

A further aspect provides a method for preparing an exfoliating composition comprising biodegradable gel-microbeads comprising the step of adding to a composition, preferably a cosmetic composition, the biodegradable gel-microbeads as taught herein.

In particular embodiments, the method for preparing an exfoliating composition comprises mixing the biodegradable gel-microbeads as taught herein with a cosmetic composition or the ingredients thereof. As a result of the excellent mechanical resistance, the gel-microbeads as taught herein remain intact during the process of mixing. Furthermore, the biodegradable microbeads as taught herein are insoluble and stable in water as well as in oil. As a result thereof, if the cosmetic composition is an emulsion, the biodegradable gel-microbeads as taught herein do not destabilize the emulsion.

The term “cosmetic composition” or “cosmetic” as used herein refers to a cosmetic grade (e.g. not deleterious to the recipient thereof) product designed to maintain, restore, improve or enhance a subject’s appearance, more particularly the appearance of the subject’s skin, including without limitation the tone, colour, complexion, texture, smoothness or softness of the subject’s skin. Cosmetic uses or methods as envisaged herein address normal, natural, or physiological processes, and can be distinguished from therapy including curative and prophylactic treatments, the purpose of which is to restore a subject from a pathological state to its original healthy condition, or to at least alleviate the symptoms of pain and suffering caused by the pathology, or to prevent pathology in the first place. Cosmetic uses or methods as intended herein can thus be denoted as “non-therapeutic”. Cosmetic uses or methods as intended herein generally employ cosmetic compositions configured for topical application to the skin.

In particular embodiments, the cosmetic composition may be formulated as a gel, cream, ointment, lotion, drops, spray, foam, or powder. The cosmetic compositions may typically be intended as ‘wash- off composition.

In particular embodiments, the cosmetic composition is a composition selected from the group consisting of face mask, face cleanser, face cream, body wash, facial wash, body lotion, shower gel, shampoo, shaving cream, hair mask, body scrub, feet scrub, and a combination thereof.

Biodegradable microbeads, wherein said microbeads comprise alginate from algae, can be prepared at about the same cost as plastic beads. Furthermore, the manufacturing process for biodegradable microbeads, wherein said microbeads comprise alginate from algae, requires less energy than the manufacturing process of plastic beads. Moreover, the environmental impact of the manufacturing process for biodegradable microbeads, wherein said microbeads comprise alginate from algae, is limited. In addition, the biodegradable gel-microbeads of present invention can be produced by various methods which allow a variable hardness and size, as well as a low size dispersion.

A further aspect provides a method for preparing biodegradable gel-microbeads comprising: reacting algae powder with an acid, thereby obtaining a mixture comprising alginic acid from insoluble salts of alginate in the algae powder; reacting the alginic acid in the mixture into a water-soluble monovalent salt of alginate, preferably a water-soluble monovalent alkali metal salt of alginate selected from the group consisting of sodium alginate, potassium alginate, ammonium alginate, lithium alginate, rubidium alginate, and cesium alginate, more preferably sodium alginate; optionally adjusting the pH of the mixture comprising the water-soluble monovalent salt of alginate to a physiological pH; and o generating microdrops of the mixture comprising the water-soluble monovalent salt of alginate; and o contacting said microdrops with a solution comprising di- and/or trivalent cations, thereby obtaining the gel-microbeads; or o contacting the mixture comprising the water-soluble monovalent salt of alginate with a solution comprising di- and/or trivalent cations, thereby obtaining a gel; and o generating gel-microbeads of the gel.

In particular embodiments, the water-soluble monovalent salt of alginate is a water-soluble monovalent metal salt of alginate. In particular embodiments, the water-soluble monovalent metal salt of alginate is an alkali metal salt of alginate, preferably an alkali metal salt of alginate selected from the group consisting of sodium alginate, potassium alginate , ammonium alginate, lithium alginate, rubidium alginate, and cesium alginate, preferably sodium alginate or potassium alginate, more preferably sodium alginate. In particular embodiment, the algae powder comprises at least one carbohydrate of algae different from alginate, preferably wherein said at least one carbohydrate of algae is a component of the cell wall of algae.

In particular embodiments, the algae powder comprises at least one carbohydrate of algae different from alginate selected from the group consisting of cellulose, hemicellulose, carrageenan, agar, ulvan, fucoidan, laminarin, mannitol, and combinations thereof, preferably at least one carbohydrate of algae selected from the group consisting of cellulose, carrageenan, agar and a combination thereof.

In particular embodiment, the algae powder comprises at least one component, preferably a structural component, of the cell wall of algae different from alginate. In particular embodiments, the algae powder comprises at least one structural polysaccharide from the cell wall of algae selected from the group consisting of cellulose, hemicellulose, carrageenan, agar, ulvan, fucoidan, and a combination thereof, preferably at least one structural polysaccharide from the cell wall of algae selected from the group consisting of cellulose, carrageenan, agar and a combination thereof.

In particular embodiments, the algae powder comprises a storage carbohydrate of algae, preferably a storage polysaccharide of algae, more preferably a storage polysaccharide selected from the group consisting of laminarin, mannitol and a combination thereof.

In particular embodiments, the algae powder comprises at least 10.0 % (w/w), at least 20.0 % (w/w), at least 25.0 % (w/w), such as at least 26.0 % (w/w), at least 27.0 % (w/w), at least 28.0 % (w/w), or at least 29.0 % (w/w), at least 30.0 % (w/w), at least 35.0 % (w/w), or at least 40.0 % (w/w), preferably at least 20.0% (w/w), , of alginate, based on the dry weight of the algae powder. In particular embodiments, the algae powder comprises from 10.0 % (w/w) to 45.0% (w/w), from 15.0% (w/w) to 40.0% (w/w), from 20.0% (w/w) to 40.0% (w/w), from 30.0% (w/w) to 40.0% (w/w), from 15.0% (w/w) to 30.0% (w/w), from 20.0% (w/w) to 30.0% (w/w), preferably from 20.0% (w/w) to 30.0% (w/w), based on the dry weight of the algae powder.

In particular embodiments, the algae powder comprises at least 20.0 % (w/w), at least 25.0 % (w/w) or at least 30.0 % (w/w), such as at least 31.0 % (w/w), at least 32.0 % (w/w), at least 33.0 % (w/w), , or at least 34.0 % (w/w), at least 35.0 % (w/w), or at least 40.0 % (w/w), preferably at least 30.0% (w/w), of alginate, based on the dry weight of the algae powder; and at least 1.0 % (w/w), such as at least 2.0 % (w/w), at least 3.0 % (w/w), at least 4.0 % (w/w), or at least 5.0 % (w/w), at least 10.0 % (w/w), at least 15.0 % (w/w), at least 20.0 % (w/w), at least 25.0 % (w/w), at least 30.0 % (w/w), at least 35.0 % (w/w), at least 40.0 % (w/w), at least 45.0 % (w/w), or at least 50.0 % (w/w), preferably at least 5.0 % (w/w), more preferably at least 10.0 % (w/w) of at least one carbohydrate of algae different from alginate, based on the dry weight of the algae powder.

In particular embodiments, the algae powder comprises, consists essentially of or consists of at least 90.0 % (w/w), at least 95.0 % (w/w), preferably at least 99.0 % (w/w), more preferably 100.0 % (w/w) of components of algae, based on the dry weight of the algae powder.

In particular embodiments, the algae powder comprises, consists essentially of or consists of at least 80.0 % (w/w), at least 85.0 % (w/w), at least 90.0 % (w/w), or at least 95.0 % (w/w), of carbohydrates (e.g. alginate and at least one carbohydrate different from alginate) of algae, based on the dry weight of the algae powder.

In particular embodiments, the algae powder is obtained by grinding or milling, preferably grinding, whole algae. In particular embodiments, the algae powder is prepared by a method comprising drying of algae and grinding or milling of the dried algae. In particular embodiments, the algae are considered dried when their water content is at most 15.0 % (w/w), at most 12.0 % (w/w), at most 10.0 % (w/w), at most 5.0 % (w/w), at most 4.0 % (w/w), at most 3.0 % (w/w), at most 2.0 % (w/w), preferably at most 5.0% (w/w).

In particular embodiments, the water content of the algae powder is from 1.0 % to 15.0 % (w/w), from 2.0 % to 15.0% (w/w), preferably from 2.0% to 12.0% (w/w).

In particular embodiments, the method for preparing biodegradable gel-microbeads as taught herein further comprises a step of drying and/or grinding algae. Preferably, the entire (i.e. whole) algae, including the cell wall, plasma membrane, cytoplasm and nucleus, is used to prepare the algae powder.

In particular embodiments, the algae powder has a Z-average particle size of less than 100.0 pm, less than 95.0 pm, less than 90.0 pm, less than 85.0 pm, less than 80.0 pm, less than 75.0 pm, less than 70.0 pm, less than 65.0 pm, less than 50.0 pm, preferably less than 75.0 pm.

In particular embodiments, the algae powder has a Z-average particle size of from 10.0 pm to 100.0 pm, from 10.0 pm to 95.0 pm, from 10.0 pm to 90.0 pm, from 10.0 pm to 85.0 pm, from 10.0 pm to 80.0 pm, from 10.0 pm to 75.0 pm, from 10.0 pm to 70.0 pm, from 10.0 pm to 65.0 pm, or from 10.0 pm to 50.0 pm.

In particular embodiments, the algae powder has a granulometry lower than 100.0 pm, lower than 95.0 pm, lower than 90.0 pm, lower than 85.0 pm, lower than 80.0 pm, lower than 75.0 pm, lower than 70.0 pm, lower than 65.0 pm, lower than 50.0 pm, preferably lower than 75.0 pm.

When referring to the properties of algae powder, the expression “a granulometry lower than X pm” indicates that at least 90% (w/w), preferably at least 95% (w/w) of the particles in the algae powder have a size lower than X pm. The concept “size of a particle” as used herein with respect to the algae powder refers to the particle size measured by means of sieve analysis.

In particular embodiments, the acid used in the step of reacting algae powder with an acid is an organic or mineral (i.e. inorganic) acid, preferably an organic or mineral (i.e. inorganic) acid selected from the group consisting of H2SO4, citric acid and HC1, more preferably H2SO4.

In particular embodiments, from 0.010 to 0.030 g, from 0.010 to 0.0250 g, from 0.010 to 0.020 g, from 0.010 to 0.0150 g, or from 0.020 to 0.030 g, of undiluted (i.e. concentrated) acid per gram of algae powder, based on the dry weight of the algae powder, is used in the step of reacting the algae powder with the acid.

In particular embodiments, the acid used in the step of reacting algae powder with an acid is a 0.2 N H2SO4 solution in water. In particular embodiments, the step of reacting algae powder with an acid comprises mixing algae powder with a H2SO4 solution. Preferably, the algae powder is mixed with the H2SO4 solution during a period of at least 60 minutes, preferably at least 120 minutes. Preferably, the algae powder is mixed with the H2SO4 solution by stirring. Preferably, the algae powder is mixed with the H2SO4 solution at room temperature. The person skilled in the art will understand that the period can be shortened if the temperature during incubation is increased. For example, if the temperature is about 50°C, the period can be reduced to about 30 minutes.

In particular embodiments, before the step of reacting the alginic acid in the mixture into the water- soluble monovalent salt of alginate, the mixture comprising alginic acid is centrifuged, thereby obtaining a pellet and a supernatant, wherein the pellet comprises substantially all (e.g. at least 95%, preferably at least 99%) of the alginic acid from the algae powder. Preferably, the centrifugation is performed during a period of at least 5 minutes, more preferably at least 10 minutes, and/or at a speed of at least 664 ref, more preferably at least 1180 ref. In particular embodiments, the supernatant is removed after centrifugation.

In particular embodiments, the step of reacting the alginic acid in the mixture into the water-soluble monovalent salt of alginate comprises contacting (e.g. mixing) the mixture comprising alginic acid with a water-soluble monovalent salt, preferably a water-soluble monovalent alkali metal salt selected from the group consisting of sodium salt, potassium salt, ammonium salt, lithium salt, rubidium salt and cesium salt, preferably sodium salt or potassium salt, more preferably sodium salt.

In particular embodiments, the step of reacting the alginic acid in the mixture into the water-soluble monovalent salt of alginate comprises contacting (e.g. mixing) the mixture comprising alginic acid with an alkali hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide or cesium hydroxide.

In particular embodiments, the step of reacting the alginic acid in the mixture into the water-soluble monovalent salt of alginate comprises contacting (e.g. mixing) the mixture comprising alginic acid with a sodium salt, a potassium salt or a sodium potassium salt, such as Na2CO3, K2CO3, NaKCCh. or NaHCO₃.

In preferred embodiments, the step of reacting the alginic acid in the mixture into the water-soluble monovalent salt of alginate comprises contacting (e.g. mixing) the mixture comprising alginic acid with a sodium salt, preferably a disodium salt, more preferably Na2CC>3, even more preferably a Na2CC>3 solution, even more preferably a 2% (w/v) Na2CC>3 solution in water.

In particular embodiments, if the method comprises a step of centrifugation before the step of reacting the alginic acid in the mixture into the water-soluble monovalent salt of alginate, the pellet obtained after centrifugation is resuspended with a monovalent salt solution, such as an alkali metal salt solution.

In particular embodiments, if the method comprises a step of centrifugation before the step of reacting the alginic acid in the mixture into sodium alginate, the pellet obtained after centrifugation is resuspended with a Na2CC>3 solution, preferably a 2 % (w/v) Na2CC>3 solution in water. In particular embodiments, the mixture comprising the alginic acid and the monovalent salt, such as the monovalent alkali metal salt, preferably disodium salt, are incubated for a period of at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 6 hours, at least 8 hours, preferably at least 5 hours. The person skilled in the art will understand that the period can be shortened if the temperature during incubation is increased.

In particular embodiments, the pH of the mixture comprising the water-soluble monovalent salt of alginate, preferably sodium alginate, is adjusted to a pH from 3.0 to 8.0, such as from 4.0 to 8.0, from 5.0 to 8.0, from 6.0 to 8.0, or from 6.0 to 7.0.

In particular embodiments, the pH of the mixture comprising the water-soluble monovalent salt of alginate, preferably sodium alginate, is adjusted to a physiological pH, preferably to a pH from 6.0 to 7.50, preferably a pH from 6.50 to 7.0. The pH of the mixture can be adjusted using all known methods in the art. Preferably, the pH of the mixture is adjusted using citric acid.

The present inventors have shown that the presence of one or more carbohydrate of algae different from alginate, preferably at least one carbohydrate of the cell wall of algae different from alginate, in the mixture comprising the water-soluble monovalent salt of alginate do not negatively influence the ability of alginate from algae to cross-link into gel-microbeads.

In particular embodiments, the method for preparing biodegradable gel-microbeads as taught herein does not comprise a step of (deliberately) removing any component, preferably any carbohydrate of algae, more preferably any structural polysaccharide of the cell wall of algae from the mixture comprising the alginic acid and/or from the mixture comprising the water-soluble monovalent salt of alginate. Carbohydrates of algae, such as carrageenan, may reinforce the alginate structure of the gelmicrobead. As a result thereof, the method of present invention allows obtaining gel-microbeads with a stronger core/ body compared to gel-microbeads only comprising alginate of algae.

The stronger core/ body of the gel-microbeads of present invention allows to prepare gel-microbeads consisting entirely out of algae components (i.e. without the need of the addition of any exogenous components for strengthening the crosslinked alginate of algae). Furthermore, the gel of the gel- microbeads of present invention itself has abrasive properties, and therefore, the gel-microbeads of present invention do not require the presence of an abrasive material other than the gel comprising alginate from algae in the gel-microbead.

As intended herein, the phrase “generating drops” particularly denotes creating a small quantity of fluid by allowing or forcing the mixture comprising the water-soluble monovalent salt of alginate, preferably sodium alginate, to fall. Preferably, said drops are formed by forcing the mixture through a cylindrical device such as a tube, a needle or a nozzle, more particularly said drops are formed through extrusion. At the exit of the cylindrical device the drops may be formed in several ways. For example, the drops may be formed by natural gravity, by vibration, by ultrasound, by laser cutting, by electrostatic enhanced dripping or by means of a cutting device such as a spinning disk, a rotating cutting jet, cutting surfaces or rotating cutting wires. Preferably the drops are formed by vibration, by ultrasound, by laser cutting, by electrostatic enhanced dripping or by mean of a cutting device such as a spinning disk, a rotating cutting jet, cutting surfaces or rotating cutting wires.

In particular embodiments, the microdrops are generated by jet-cutting. In more particular embodiments, the microdrops are generated by cutting a flow of the mixture with the aid of a cutting device, preferably rotating wires, as described elsewhere herein.

As intended herein, the phrase “contacting said microdrops with a solution” as used herein particularly denotes bringing the drops according to the invention in immediate proximity with a solution. Upon contact of the microdrops with the solution, the microdrops instantly jellify into gel-microbeads.

The person skilled in the art will understand that if the microdrops are generated by jet-cutting, the shape of the microdrops may change from a drop-like shape immediately after cutting the flow of the mixture to a spherical shape before being contacted with the solution comprising di- and/or trivalent cations.

As intended herein, the phrase “contacting the mixture comprising the water-soluble monovalent salt of alginate with a solution comprising di- and/or trivalent cations” as used herein particularly denotes bringing the mixture comprising the water-soluble monovalent salt of alginate in immediate proximity with a solution comprising di- and/or trivalent cations. Upon contact of the mixture with the solution, the mixture instantly jellifies into a gel.

In particular embodiments, the microdrops of the mixture comprising the water-soluble monovalent salt of alginate are let in the solution comprising di- and/or trivalent cations for a time period of at least 1 minute, at least 2 minutes, at least 3 minutes, at least 4 minutes, at least 5 minutes, at least 10 minutes, at least 15 minutes, or at least 20 minutes, preferably at least 20 minutes.

In particular embodiments, the mixture comprising the water-soluble monovalent salt of alginate is let in the solution comprising di- and/or trivalent cations for a time period of at least 1 minute, at least 2 minutes, at least 3 minutes, at least 4 minutes, at least 5 minutes, at least 10 minutes, at least 15 minutes, or at least 20 minutes, preferably at least 20 minutes.

In particular embodiments, said di- and/or trivalent cations in the solution with which the microdrops are contacted can be alkali metals, alkali-earth metals, transition metals or other metals. In particular embodiments, said di- and/or trivalent cations in the solution with which the microdrops are contacted are selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

In particular embodiments, said di- and/or trivalent cations in the solution with which the mixture comprising the water-soluble monovalent salt of alginate is contacted can be alkali metals, alkali-earth metals, transition metals or other metals. In particular embodiments, said di- and/or trivalent cations in the solution with which the mixture comprising the water-soluble monovalent salt of alginate is contacted are selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

In particular embodiments, the contacting of the mixture comprising the water-soluble monovalent salt of alginate with a solution comprising di- and/or trivalent cations, thereby obtaining a gel; and generating gel-microbeads of the gel is performed in one step, such as by spray drying. For example, a bi-fluidic nozzle may be used to mix the mixture comprising the water-soluble monovalent salt of alginate and the solution comprising di- and/or trivalent cations and disperse them in the form of microbeads.

In particular embodiments, the method for preparing biodegradable gel-microbeads further comprises a step of washing and/or drying the gel-microbeads, such as for storage. Methods of washing and/or drying gel-microbeads are known in the art. For example, the gel-microbeads may be washed with demineralized water and/or dried at a temperature from 35°C to 45°C, preferably 40.0°C.

In particular embodiments, the method for preparing biodegradable gel-microbeads comprises a step of drying the gel-microbeads until a final water content of at most 20 % (w/w), at most 15 % (w/w), at most 10 % (w/w), at most 5 % (w/w), preferably at most (w/w), is reached.

In particular embodiments, the method for preparing biodegradable gel-microbeads comprises a step of drying the gel-microbeads until a final water content of from 1 to 30 % (w/w), from 5 to 30 % (w/w), from 10 to 30 % (w/w), from 15 to 30 % (w/w), from 5 to 25 % (w/w), from 5 to 20 % (w/w), from 10 to 20 % (w/w) or from 15 to 20 % (w/w), preferably from 15 to 30% (w/w), is reached.

For certain applications of the microbeads, it could be desirable that the microbeads do not have any colour. Accordingly, the algae might be decoloured prior to grinding the algae into an algae powder or the algae powder might be decoloured prior to reacting it with the acid. Alternatively, the method as taught herein might further comprise a step of decolouring the microbeads.

In particular embodiments, the method further comprises a step of decolouring the gel-microbeads. Decolouring of microbeads might be achieved by any method known in the art such as using ultraviolet radiation, hydrogen peroxide oxidation and/or activated carbon.

In particular embodiments, the step of decolouring the gel-microbeads comprises exposing the microbeads to ultraviolet (UV) radiation, such as UV at a wavelength of from 200 to 400 nm, from 200 nm to 300 nm or from 300 nm to 400 nm, preferably from 250 to 370 nm, such as 254 nm, 312 nm or 365 nm, more preferably from 200 to 300 nm, such as about 254 nm.

In particular embodiments, the step of decolouring the gel-microbeads comprises contacting the gel- microbeads with a hydrogen peroxide solution, preferably a 0.6 % (v/v) hydrogen peroxide solution. Preferably, the contacting of the gel-microbeads with the hydrogen peroxide solution is performed at a temperature from 35.0 °C to 45.0 °C, preferably at a temperature from 40.0 °C. In particular embodiments, the step of decolouring the gel-microbeads comprises contacting the gelmicrobeads with a hydrogen peroxide solution, preferably a 0.6 % (v/v) hydrogen peroxide solution, and exposing the gel-microbeads to UV radiation.

In particular embodiments, the step of decolouring the gel-microbeads comprises contacting the gel- microbeads with activated carbon.

A further aspect provides a biodegradable gel-microbead obtainable by the method as taught herein.

The particular embodiments relating to the properties of the biodegradable gel-microbeads used in any preceding aspects, such as the compositions, methods and uses described above, are as described elsewhere, such as in the particular embodiments of the biodegradable gel-microbeads of the invention.

The present application also provides aspects and embodiments as set forth in the following Statements:

Statement 1. An exfoliating composition comprising biodegradable gel-microbeads, wherein said gel- microbeads comprise alginate from algae.

Statement 2. The exfoliating composition according to statement 1, wherein the exfoliating composition is a skin cleansing composition, an exfoliating shower gel, an exfoliating hair care composition, or a body or feet scrub composition.

Statement 3. The exfoliating composition according to statement 1 or 2, wherein the exfoliating composition comprises from 0.10 to 15.0 % (w/w) of said gel-microbeads.

Statement 4. Use of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae, as exfoliant.

Statement 5. Use of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae, for skin texture refining, wrinkle regression and/or for cleaning teeth.

Statement 6. The exfoliating composition according to any one of statements 1 to 3, or the use according to statement 4 or 5, wherein the alginate is multivalent cation crosslinked alginate.

Statement 7. A biodegradable gel-microbead comprising multivalent cation crosslinked alginate from algae.

Statement 8. The exfoliating composition according to any one of statements 1 to 3 or 6, the use according to any one of statements 4 to 6, or the biodegradable gel-microbead according to statement 7, wherein the gel-microbead(s) further comprise(s) at least one carbohydrate of algae different from alginate, preferably wherein said at least one carbohydrate of algae is a component of the cell wall of algae. Statement 9. The exfoliating composition according to statement 8, the use according to statement 8, or the biodegradable gel-microbead according to statement 8, wherein the at least one carbohydrate of algae different from alginate is selected from the group consisting of cellulose, hemicellulose, carrageenan, agar, ulvan, fucoidan, laminarin, mannitol, and combinations thereof.

Statement 10. The exfoliating composition according to any one of statements 1 to 3, 6, 8 or 9, the use according to any one of statements 4 to 6, 8 or 9, or the biodegradable gel-microbead according to any one of statements 7 to 9, wherein the biodegradable gel-microbead is prepared starting from whole algae powder.

Statement 11. The exfoliating composition according to any one of statements 1 to 3, 6, or 8 to 10, the use according to any one of statements 4 to 6, or 8 to 10, or biodegradable gel-microbead according to any one of statements 7 to 10, wherein the multivalent cation is a di- and/or trivalent cation, preferably a di- and/or trivalent cation selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

Statement 12. The exfoliating composition according to any one of statements 1 to 3, 6 or 8 to 11, the use according to any one of statements 4 to 6, or 8 to 11, or the biodegradable gel-microbead according to any one of statements 7 to 11, wherein the algae are marine algae, preferably algae with an alginate content of at least 30.0 % (w/w), based on total biomass dry weight.

Statement 13. The exfoliating composition according to any one of statements 1 to 3, 6 or 8 to 12, the use according to any one of statements 4 to 6 or 8 to 12, or the biodegradable gel-microbead according to any one of statements 7 to 12, wherein said gel-microbeads are prepared by jet-cutting.

Statement 14. A method for preparing an exfoliating composition comprising biodegradable gel- microbeads comprising the step of adding to a composition the gel-microbeads according to any one of statements 7 to 13.

Statement 15. A method for preparing biodegradable gel-microbeads comprising: reacting algae powder with an acid, thereby obtaining a mixture comprising alginic acid from insoluble salts of alginate in the algae powder; reacting the alginic acid in the mixture into a water-soluble monovalent salt of alginate; optionally adjusting the pH of the mixture comprising the water-soluble monovalent salt of alginate to a physiological pH; and o generating microdrops of the mixture comprising the water-soluble monovalent salt of alginate; and o contacting said microdrops with a solution comprising di- and/or trivalent cations, thereby obtaining the gel-microbeads; or o contacting the mixture comprising the water-soluble monovalent salt of alginate with a solution comprising di- and/or trivalent cations, thereby obtaining a gel; and o generating gel-microbeads of the gel.

Statement 16. The method according to statement 15, wherein the algae powder is obtained by grinding whole algae.

Statement 17. The method according to statement 15 or 16, wherein the acid is H2SO4.

Statement 18. The method according to any one of statements 15 to 17, wherein the water-soluble monovalent salt of alginate is sodium alginate and the step of reacting the alginic acid in the mixture Statement into sodium alginate comprises contacting the mixture comprising alginic acid with Na2CC>3.

Statement 19. The method according to any one of statements 15 to 18, wherein said di- and/or trivalent cations are selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

Statement 20. The method according to any one of statements 15 to 19, wherein the method further comprises a step of decolouring the gel-microbeads, preferably by ultraviolet and hydrogen peroxide oxidation.

Statement 21. The method according to any one of statements 15 to 20, wherein the microdrops are generated by jet-cutting.

Statement 22. A biodegradable gel-microbead obtainable by the method according to any of statements 15 to 21.

The above aspects and embodiments are further supported by the following non-limiting examples.

EXAMPLES

Example 1: Preparation of biodegradable gel-microbeads as taught herein

The preparation of biodegradable gel-microbeads is illustrated in Figure 1.

IJj Grindmg,

First, whole algae of the species Laminaria Hyperb area or Digitata were grinded with a kitchen crusher. Subsequently, 500 g of grinded algae was put into a mill ball and grinded further during a period of 40 to 60 minutes at a speed of 86 to 194 T/mins. Next, the mill ball and the algae were sorted in a box. Then, the obtained algae powder was sifted through a sieve with a pore size of 75.0 pm to isolate the particles with a Z-average particle size smaller than 75.0 pm. Sieving was performed on an agitator plate. The residue of particles equal to or larger than 75.0 pm can be ground again or can be used to make microbeads with a larger Z-average particle size. l .2) Chcmical trcatmcnt,

In the algae, alginate is present in an insoluble salt form. The first step of the chemical treatment allows turning the insoluble salt form of alginate into alginic acid. Alginic acid is also insoluble.

The second step of the chemical treatment is an alkaline extraction. With sodium salt, the insoluble alginic acid turns into the soluble sodium alginate. The reagent is sodium carbonate.

More particularly, 75 g of grinded algae was demineralised using 400 ml of a 0.2N H2SO4 solution during a period of 1 hour while stirring. Next, the mixture of the grinded algae and the H2SO4 solution was centrifuged for a period of 10 minutes at 4000 rpm (1180 ref). Subsequently, the supernatant was discarded. Then, the pellet was washed twice with demineralized water by adding water to the pellet, resuspending the pellet, centrifuging the resuspended pellet for 5 minutes at 4000 rpm (1180 ref), discarding the supernatant and repeating all of these steps. Further, 750 ml of a 2% (w/v) Na₂CO3 solution was added to the demineralised algae and left to rest for 5 hours while stirring. When the viscosity increased, 2 g of citric acid was added to increase the pH up to 7.0. A hand mixer was used to homogenize the mix.

The mixture comprising sodium alginate (as obtained at the end of section 1.2 above) was transformed into microbeads using jet cutting and pressurized air.

Alginate solidifies by ionotropic gelation. In contact with multivalent ions, a hydrophilic and reticulated polymer is formed.

The mixture comprising sodium alginate (as obtained at the end of section 1.2 above) was put in the tank of the jet-cutter and closed. The tank was put under pressure. Next, a 2% (w/v) CaC’h solution was poured into a tub while stirring and placed underneath the tank. Then, the rotation speed of the spinning disk of the jet-cutter was adjusted and the valve of the jet-cutter tank was opened to allow drops of the mixture comprising sodium alginate to fall into the tub comprising the 2% (w/v) CaC’h solution, thereby obtaining gel-microbeads. Table 1. Tested ions and results thereof.

N/A: not applicable

_5)_ Washing. H.d. dry.i(lS-. Subsequently, the obtained gel-microbeads were dried for storage.

First, the gelling bath was poured into the bowl of a fluidized bed. The CaC’h was discarded. Next, the gel-microbeads were washed in the fluidized bed bowl with demineralized water. Then, the microbeads were put in a bowl for 2 hours in a stove at 40.0°C. The bowl was put on the fluidized bed at a temperature of 40.0°C, at an air flow of 70, for a period of 10 minutes. Then, the gel-microbeads were mixed and placed at a temperature of 40.0°C, at a maximum air flow, for a period of 10 minutes. This step was repeated until drying.

Next, the granulometry, viscosity, weight, colour, smell, texture and form of the biodegradable gel- microbeads were tested in a stability study. In the stability study, the gel-microbeads are incorporated into a cream. A cream without gel-microbeads was used as a control. The study was conducted for three months. The stability study was conducted in 5 different conditions (A/O/F/E/C):

The general aspect was analysed:

• Squareness form: the microbeads can keep their form within the cream. The scale: 0 to 10. 0: the microbeads mash. 10: keep their form;

• Firmness: the strength to compress the microbeads within the cream. The scale: 0 to 10. 0 if the microbeads don’t need strength to compress. 10 if the strength is high;

• Spread out: the capacity of the product to uniformly spread out on the skin. The scale: 0 to 10. 0 doesn’t spread out. 10: spread out quickly;

• Residual quantity: 0 for no residue and 10 if the product stick on the skin.

Aesthetic properties: colour; smell; tacky; flow; hardness.

Physico-chemical properties: pH; viscosity.

Microbiological properties: aerobic mesophilic bacteria; yeast and mold.

The study was conducted for 3 months in cream and in the same cream with microbeads. All the properties were kept for conditions AOFE. A slightly sea smell was detected in the cream and the viscosity decrease (in cream and cream with microbeads). For C conditions, the emulsion was destabilized in cream and in cream with microbeads.

The algae powder and microbeads do not comprise chromium, nickel or arsenic. The microbeads prepared with BaCCF contain 15.7% (w/w) of Ba²⁺. Results:

All the properties were kept for conditions AOFE. A slightly sea smell was detected in the cream comprising gel-microbeads and the viscosity of the cream comprising gel-microbeads was found to slightly decrease over time (compared to a cream without gel-microbeads). For condition C, the emulsion was destabilized in cream and in cream with microbeads.

Example 2. Decolouration of biodegradable microbeads

The biodegradable microbeads obtained by the process as described in Example 1 are decoloured. This is achieved by suspending the biodegradable microbeads in a 0.6% (v/v) H2O2 solution and exposing the suspended biodegradable microbeads to UV light at a temperature of about 40.0°C for 72 hours.

Figure 2 shows the resulting decolorated microbeads. Example 3. Exfoliating composition comprising biodegradable microbeads

An exfoliating cream is prepared by mixing 3 % (w/w) of biodegradable microbeads comprising multivalent cation crosslinked alginate from algae and at least one carbohydrate of algae different from alginate as taught herein having a mean particle size of about 400+/-80 pm, water, isoamyl laurate, glyceryl stearate citrate, brassica alcohols, glycerin, glyceryl caprylate, glycine soja oil, lecithin, sodium hydroxy de, tocopherol, and xanthan gum.

Figure 3 shows the exfoliating cream comprising the biodegradable microbeads as taught herein. The biodegradable microbeads are individually distinguishable by the eye within the cream.

Example 4. Biodegradability of the gel-microbeads

The OECD 301F method (version of July 26, 2013), which is a manometric respirometry test, was performed by Scanae (laboratory with expertise in biodegradability; Mons, Belgium) to determine the biodegradability of the gel-microbeads. This method measures the oxygen consumption consumed by bacteria in order to mineralize the test substance, in this case the gel-microbeads are the sole source of carbon. The amount of oxygen consumed is deduced via the pressure variation in the test flask using the OxiTop® device.

4.1 Microbeads gelled with Ca²⁺ ions

After a 3-day latency period, the rate of biodegradation achieved within a 10-day interval was 62%. After the normal duration of the test, i.e. 28 days, an 82% biodegradability rate was reached. The test was extended to 60 days, the extreme limit, for which a rate of 93% was reached (Figure 4A).

The results show that the gel-microbeads comprising calcium ions as taught herein qualify as being easily biodegradable.

4.2 Microbeads gelled with Ba²⁺ ions

After a 3-day latency period, the rate of biodegradation achieved within a 10-day interval is 78%. After the normal duration of the test, i.e. 28 days, 98% biodegradability rate was reached. The test therefore ended after 28 days (Figure 4B).

The results show that the gel-microbeads comprising barium ions as taught herein qualify as being easily biodegradable.

Example 5. Hardness of the gel-microbeads

The hardness of gel-microbeads made using Ba²⁺ or Ca²⁺ was tested using nano-indentation.

Test parameters: Target load: 100 mN

Loading rate: 200 mN/min

Unloading rate: 200 mN/min

Approach speed: 100 pm/min Contact load: 0.015 mN

Creep: 10 s

Material: diamond

Results: The Ba²⁺ microbeads had a hardness of 124.662 (± 6.877) MPa and an elasticity of 4.487 (± 0.442) Gpa.

The Ca²⁺ microbeads had a hardness of 53.351 (±3.820) MPa and an elasticity of 1.987 (±0.215).

Claims

1. An exfoliating composition comprising biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae and wherein said biodegradable gel-microbeads are prepared starting from whole algae powder.

2. The exfoliating composition according to claim 1, wherein the exfoliating composition is a skin cleansing composition, an exfoliating shower gel, an exfoliating hair care composition, or a body or feet scrub composition.

3. The exfoliating composition according to claim 1 or 2, wherein the exfoliating composition comprises from 0.10 to 15.0 % (w/w) of said gel-microbeads.

4. Use of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae and wherein said gel-microbeads are prepared starting from whole algae powder, as exfoliant.

5. Use of biodegradable gel-microbeads, wherein said gel-microbeads comprise alginate from algae and wherein said gel-microbeads are prepared starting from whole algae powder, for skin texture refining, wrinkle regression and/or for cleaning teeth.

6. The exfoliating composition according to any one of claims 1 to 3, or the use according to claim 4 or 5, wherein the alginate is multivalent cation crosslinked alginate.

7. A biodegradable gel-microbead comprising multivalent cation crosslinked alginate from algae, wherein said gel-microbead is prepared starting from whole algae powder.

8. The exfoliating composition according to any one of claims 1 to 3 or 6, the use according to any one of claims 4 to 6, or the biodegradable gel-microbead according to claim 7, wherein the gel-microbead(s) further comprise(s) at least one carbohydrate of algae different from alginate, preferably wherein said at least one carbohydrate of algae is a component of the cell wall of algae.

9. The exfoliating composition according to claim 8, the use according to claim 8, or the biodegradable gel-microbead according to claim 8, wherein the at least one carbohydrate of algae different from alginate is selected from the group consisting of cellulose, hemicellulose, carrageenan, agar, ulvan, fucoidan, laminarin, mannitol, and combinations thereof.

10. The exfoliating composition according to any one of claims 1 to 3, 6, 8 or 9, the use according to any one of claims 4 to 6, 8 or 9, or biodegradable gel-microbead according to any one of claim 7 to 9, wherein the multivalent cation is a di- and/or trivalent cation, preferably a di- and/or trivalent cation selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

11 . The exfoliating composition according to any one of claims 1 to 3, 6 or 8 to 10, the use according to any one of claims 4 to 6, or 8 to 10, or the biodegradable gel-microbead according to any one of claims 7 to 10, wherein the algae are marine algae, preferably algae with an alginate content of at least 30.0 % (w/w), based on total biomass dry weight.

12. The exfoliating composition according to any one of claims 1 to 3, 6 or 8 to 11, the use according to any one of claims 4 to 6 or 8 to 11, or the biodegradable gel-microbead according to any one of claims 7 to 11, wherein said gel-microbeads are prepared by jet-cutting.

13. A method for preparing an exfoliating composition comprising biodegradable gel-microbeads comprising the step of adding to a composition the gel-microbeads according to any one of claims 7 to 12.

14. A method for preparing biodegradable gel-microbeads comprising: reacting whole algae powder with an acid, thereby obtaining a mixture comprising alginic acid from insoluble salts of alginate in the whole algae powder; reacting the alginic acid in the mixture into a water-soluble monovalent salt of alginate; optionally adjusting the pH of the mixture comprising the water-soluble monovalent salt of alginate to a physiological pH; and o generating microdrops of the mixture comprising the water-soluble monovalent salt of alginate; and o contacting said microdrops with a solution comprising di- and/or trivalent cations, thereby obtaining the gel-microbeads; or o contacting the mixture comprising the water-soluble monovalent salt of alginate with a solution comprising di- and/or trivalent cations, thereby obtaining a gel; and o generating gel-microbeads of the gel.

15. The method according to claim 14, wherein the whole algae powder is obtained by grinding whole algae.

16. The method according to claim 14 or 15, wherein the acid is H2SO4.

17. The method according to any one of claims 14 to 16, wherein the water-soluble monovalent salt of alginate is sodium alginate and the step of reacting the alginic acid in the mixture into sodium alginate comprises contacting the mixture comprising alginic acid with Na2CC>3.

18. The method according to any one of claims 14 to 17, wherein said di- and/or trivalent cations are selected from the group consisting of Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Al³⁺, Sr²⁺, and combinations thereof.

19. The method according to any one of claims 14 to 18, wherein the method further comprises a step of decolouring the gel-microbeads, preferably by ultraviolet and hydrogen peroxide oxidation.

20. The method according to any one of claims 14 to 19, wherein the microdrops are generated by jetcutting.

21. A biodegradable gel-microbead obtainable by the method according to any of claims 14 to 20.