WO2025068025A1

WO2025068025A1 - Methods for evenly distributing a hydrophobic liquid in a powder

Info

Publication number: WO2025068025A1
Application number: PCT/EP2024/076274
Authority: WO
Inventors: Poul Bach; Alexander Findeisen
Original assignee: Novozymes AS
Current assignee: Novozymes AS
Priority date: 2023-09-29
Filing date: 2024-09-19
Publication date: 2025-04-03
Anticipated expiration: 2026-03-29
Also published as: WO2025068026A1

Abstract

The invention provides methods for evenly distributing small amounts of a hydrophobic liquid on the surface of a plurality of particles.

Description

METHODS FOR EVENLY DISTRIBUTING A HYDROPHOBIC LIQUID IN A POWDER

FIELD OF THE INVENTION

The present invention relates to methods for evenly distributing small amounts of a hydrophobic liquid on the surface of a plurality of particles.

BACKGROUND

Biological powder products often contain high amounts of protein, and since proteinaceous dust is a known health hazard, it is important to reduce it as much as possible.

It is well-known that powders can be dedusted by applying small amounts of oil to a powder composition to capture dust released from powder particles during production and handling. However, it is challenging to distribute a very small amount of liquid evenly over the surface of a powder. Spraying a small amount of oil onto a powder requires a small droplet size to achieve an even distribution of the oil over the entire particle surface. Breaking up a liquid into such small droplets requires high energy input and high air to liquid ratios to achieve sufficient atomization in a two-fluid nozzle.

A different solution is disclosed in WO 2016/114648, where a granular oil containing dedusting material is described. By “immobilizing” an oil on a flour/starch carrier, the oil can be distributed in a powder using a mixer, without the need for complex spray processes. However, since the carrier is added to and remains in the resulting powder product, this will dilute the product concentration. Further, achieving a uniform powder product requires vigorous mixing, and the flour/starch carrier may not be compatible with the final product application.

SUMMARY OF THE INVENTION

The present invention provides, in a first aspect, a method for evenly distributing a hydrophobic liquid on the surface of a plurality of particles, comprising

(a) providing a plurality of particles having a Dso in the range of 100-2000 pm

(b) spraying an oil-in-water emulsion of the hydrophobic liquid onto the plurality of particles in a fluidized bed.

Other aspects and embodiments of the invention are apparent from the description and examples.

Unless otherwise indicated, or if it is apparent from the context that something else is meant, all percentages are percentage by weight (% w/w).

As used herein, the term "consists essentially of" (and grammatical variants thereof), as applied to the compositions and methods of the invention, means that the compositions/methods may contain additional components so long as the additional components do not materially alter the composition/method. As used herein, the term "essentially free of' (and grammatical variants thereof), as applied to the compositions and methods of the invention, means that the compositions/methods may contain minor amounts of the specified component so long as the amount of the component does not materially alter, or provide any material effect on, the composition/method. In an embodiment, "essentially free of" means 0% w/w.

The term “plurality of particles” as used in the context of the invention is the number of particles necessary to determine the particle size distribution with a reasonable accuracy, but at least 50 particles (randomly sampled), such as at least 100, 500 or 1000 particles. Typically, a plurality of particles is one or a few grams of particles. Particle size distribution may be measured using laser diffraction methods or optical digital imaging methods or sieve analysis. Unless otherwise indicated, the particle size is the volume based particle diameter (and the average particle size, Dso, is the volume average particle diameter), which is the same as the weight based particle diameter if the densities of the particles are the same.

Brief description of the Figures

Figure 1 shows the scooping box set-up used in the examples.

Figure 2 shows a typical dust response measured by DustTrack DRX in the examples.

DETAILED DESCRIPTION

We have found that by using emulsion technology, it is possible to apply very small amounts of a hydrophobic liquid to a fluidized powder. This is useful for making dedusted particulate products, or simply for applying a small amount of an (oil soluble) active ingredient to a particulate substrate.

It is not important what type of ingredients are contained in the fluidized powder (plurality of particles), but protein containing powders are particularly preferred, because of the health hazards associated with inhalation of proteinaceous dust.

It is highly advantageous that the method of the invention does not leave a “carrier” in the product and does not dilute the product to any significant extent. The water from the emulsion, which could be considered a carrier, will simply evaporate in the fluid bed operation. The oil phase could even be used as a carrier for oil-soluble active ingredients used in very small amounts, like vitamins, perfumes/fragrances, colors/dyes, preservation agents and antioxidants like BHA, BHT, propyl gallate, TBHQ, tocepherols, carotene, etc.

Thus, the present invention provides a method for evenly distributing a hydrophobic liquid on the surface of a plurality of particles, comprising

(a) providing a plurality of particles having a Dso in the range of 100-2000 pm, and

(b) spraying an oil-in-water emulsion of the hydrophobic liquid onto the plurality of particles in a fluidized bed. Preferably, the plurality of particles has a D50 in the range of 100-1000 pm.

Preferably, the fluidized bed is a fluidized bed spray coater.

The plurality of particles may be made by spray drying a protein containing liquid, such as an enzyme containing liquid, to produce a protein or enzyme powder, which is subsequently agglomerated, for example in a fluidized bed, to produce the plurality of particles.

In an embodiment, the plurality of particles is a protein containing powder or granulate, preferably an enzyme powder or granulate.

In an embodiment, the emulsion is sprayed with a droplet size having a D50 in the range of 1-100 pm; preferably in the range of 1-75 pm, or in the range of 1-50 pm.

In an embodiment, the emulsion is sprayed onto the plurality of particles for a time sufficient to provide a plurality of particles comprising 0.1-10% w/w of the hydrophobic liquid.

In an embodiment, the plurality of particles is also sprayed with a binder; preferably a polysaccharide binder, such as maltodextrin.

The present invention provides methods for making granulates with excellent properties, having very low amounts of dust. Thus, in another aspect, the invention also provides an enzyme granulate produced by the methods of the invention, which exhibits an angle of repose of less than 60°, a Heubach 1 of less than 5 ppm, and/or an “Area under the curve” of less than 5%.

Oil-in-water emulsion

Oil-in-water emulsions are hydrophobic/oil droplets dispersed in a continuous aqueous phase (in contrast to water-in-oil emulsion where aqueous droplets are dispersed in an oil continuum). Emulsions may be prepared and stabilized using surface active components (molecules or particles) that have an affinity to the water/oil interface (emulsifiers).

Emulsifiers suitable for making emulsions used in the invention are well-known in the art and some are described below.

In an embodiment, the emulsion comprises 1-50% w/w of the hydrophobic liquid; preferably 1-35% w/w, or 1-20% w/w of the hydrophobic liquid.

In an embodiment, the droplet size of the hydrophobic liquid in the emulsion has a D50 in the range of 1-20 pm; preferably in the range of 1-10 pm, or in the range of 1-5 pm.

Hydrophobic liquid

The oil used to prepare the oil-in-water emulsion is a hydrophobic liquid, substantially insoluble in water at room temperature, for example having a solubility in water of less than 1% w/w at 25°C. In an embodiment, the hydrophobic liquid has an octanol-water partition coefficient, logP, higher than 0 (zero). The hydrophobic liquid may also have a vapor pressure of less than 1 kPa at 25°C.

Many kinds of hydrophobic liquids can be used, e.g., organic (vegetable) oils, hydrocarbon (mineral, paraffinic) oils, silicone oils, etc.

Oils are often divided into natural and synthetic oils. Synthetic oils can be hydrocarbons like mineral oils, e.g., paraffinic oils or silicone oils. Natural oils can be vegetable oils like fatty acids and mono- di- or triglycerides, but also other kinds of plant oils like fatty alcohol derived oil like esters or ethers, e.g. PPG stearyl ethers, dicaprylyl carbonate and many others are frequently used in the art. It is preferred to use oils which are liquid at room temperature, but higher melting types (fats/waxes) can also be used if emulsified at temperatures where they are molten.

Preferably, the hydrophobic liquid is an oil, preferably an edible oil, more preferably a plant oil.

Rheology modifying additives

Rheology modifiers are additives that changes the rheology of the phase. They are typically used to either thicken or thinning the viscosity, and/or to make shear thinning or thixotropic behavior. Addition of rheology modifiers can significantly improve the physical stability of emulsions. Many types of rheology modifiers are known in the art, both soluble and particulate types.

Emulsifiers

A variety of emulsifiers are known in the art. An emulsifier (also known as an "emulgent") is a substance that stabilizes an emulsion by increasing its kinetic stability. One class of emulsifiers is known as "surface active agents", or surfactants. Emulsifiers are compounds that typically have a polar or hydrophilic (i.e. , water-soluble) part and a non-polar (i.e. , hydrophobic or lipophilic) part. Because of this, emulsifiers tend to have more or less solubility either in water or in oil. Emulsifiers that are more soluble in water (and conversely, less soluble in oil) will generally form oil-in-water emulsions, while emulsifiers that are more soluble in oil will form water-in-oil emulsions. Wilder Dwight Bancroft stated in 1910 that "The phase in which an emulsifier is more soluble constitutes the continuous phase." (Bancroft’s rule). This is a general rule that most often is correct.

Emulsifiers can be divided into low molecular weight emulsifiers and polymeric emulsifiers, either block polymers with one more more hydrophilic and hydrophobic blocks or random polymers with distributed hydrophilic and hydrophobic areas. Another class of emulsifiers is particles that absorb to the interphase between and can form so-called Pickering emulsions.

Examples of emulsifiers (including emulsion stabilizers) that are most used for water-in-oil or oil-in-water emulsions are alkoxylated alcohols such as Marlipal 24/70 (Sasol) or Berol 050 (Nouryon), glyceryl esters or derivatives thereof such as ISOLAN® GPS (Evonik) or Plurol® Diisostearique CG (Gattefosse), alkyl ether sulfates (the most commonly used is sodium laureth sulfate) such as Sulfochem™ ES-2BZ (Lubrizol), esters such as Cithrol™ DPHS (Croda), sorbitan derivatives such as Span™ 20 or Tween™ 80 (Croda), non-glycerol ester based siloxanes and silanes such as ABIL® EM90 or ABIL® EM 180 (Evonik), or mixtures of the above cited such as ISOLAN® 17 MB or ABIL® EM97 S (Evonik). Amphoteric polymeric emulsifiers as described in WO 97/24177, page 19-21 ; and in WO 99/01534. Well known particles used for obtaining and stabilizing Pickering emulsions are BENTONE® 34 (Elementis) or AEROSIL® R 972 (Evonik), but many others are known in the art.

Combinations of emulsifiers, or emulsifiers and emulsion stabilizers can be used. This can e.g. be combinations of smaller and larger molecules, or even soluble and particulate (Pickering type) emulsifiers. In some cases, one emulsifier if predominantly responsible for obtaining the right droplet size (e.g., a monomeric type emulsifier), while another emulsifier (or emulsion stabilizer, e.g. polymeric emulsifier or stabilizer) predominantly ensures that coalescence is minimized. In other cases combination of emulsifiers (and surfactants) can be used to optimize viscosity of the final emulsion. In some cases combination of predominantly oil-soluble and predominantly water-soluble emulsifiers are used.

Processes

The emulsions of the invention can be prepared by high-speed mixing or stirring of the oil phase, the aqueous phase and the emulsifier. In this way, stable emulsions are obtained, which can be stably stored in this form. However, it may not be necessary to make a highly stable emulsion if it is sprayed onto the plurality of particles, according to the invention, within seconds or minutes. In a fluid bed, the emulsion can even be prepared in-situ by feeding the two emulsion phases simultaneously to a suitable nozzle.

Many other processes for making emulsions are known in the art, such as, dynamic or static mixers, high shear mixers/disperser/homogenizer, membrane emulsification, microfluidizers, ultrasound (acoustic) emulsification, high pressure homogenizers, colloidal mills, and self-emulsification. The process can be run in batch or continuous, as ’’one pass”, ’’multipass” or using ’’recirculation”. Often in two or more steps (often using different equipment/technologies in the steps) - first a ’’rough” emulsion is produced, then finer droplets are created in subsequent steps. Particles

The plurality of particles for use with the invention is a particulate composition, such as a powder, that can be fluidized in a fluid bed. Such compositions may be free-flowing before fluidization, for example exhibiting an angle of repose of less than 60°, preferably less than 50°, less than 40°, less than 30°, or less than 20°.

The particles may be a spray-dried or milled powder, or they may be produced by various techniques, such as crystallization, precipitation, pan-coating, fluid bed coating, fluid bed agglomeration, rotary atomization, extrusion, prilling, spheronization, size reduction methods, drum granulation, and/or high shear granulation. Such techniques are, for example, described on page 5-6 of WO 2022/171872.

The size of the particles is not important, but they must be suitable for fluidization in a fluid bed. In an embodiment, the particles have a Dso in the range of 100-2000 pm, preferably a Dso in the range of 100-1000 pm.

Preferred particles are protein or enzyme particles. As described above, it may be desirable to apply a small amount of oil to protein/enzyme particles to capture any protein/enzyme dust formed during production and handling.

Proteins

The particles used in the invention may comprise protein(s). Proteins may be isolated directly from a natural source or produced by fermentation of a microbial host cell. Proteinaceous dust is a well-known health hazard and need to be controlled during production and use of protein containing particles.

Such proteins may be small (peptides; <50 amino acids) or large (polypeptides; >50 amino acids) biomolecules that perform a vast array of functions within living organisms, including catalyzing reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins are composed of chains of polymerized amino acids, which are folded in a very specific three- dimensional structure. The three-dimensional structure is critical for maintaining the function of the protein. Some chemicals can change the folding, or even unfold (denaturing) the three- dimensional structure, which will result in loss of function, such as loss of enzymatic activity.

In an embodiment, the proteins are polypeptides; preferably globular proteins/polypeptides. In another embodiment, the proteins are soluble at physiological conditions.

Proteins fall into at least four distinct groups, namely enzymes, cell signaling proteins, ligand binding proteins, and structural proteins.

In another embodiment, the at least one polypeptide of interest comprises a therapeutic polypeptide selected from the group consisting of an antibody, an antibody fragment, an antibody-based drug, a Fc fusion protein, an anticoagulant, a blood factor, a bone morphogenetic protein, an engineered protein scaffold, a growth factor, a blood clotting factor, a hormone, an interferon (such as an interferon alpha-2b), an interleukin, a lactoferrin, an alphalactalbumin, a beta-lactalbumin, an ovomucoid, an ovostatin, a cytokine, an obestatin, a human galactosidase (such as an human alpha-galactosidase A), a vaccine, a protein vaccine, and a thrombolytic.

Enzymes are described below.

Cell signaling and ligand binding proteins include proteins such as, for example, receptors, membrane proteins, ion channels, antibodies (e.g. single-domain antibodies), hormones, hemoglobin, and hemoglobin-like molecules. Heme-containing enzymes, such as peroxygenases and peroxidases, may comprise enzyme activity, or may be inactivated hemecontaining enzyme variants.

Structural proteins provide stiffness and rigidity to otherwise-fluid biological components. Preferably, the proteins are enzymes, cell signaling proteins, or ligand binding proteins; more preferably the proteins are enzymes.

Enzymes

Enzymes are catalytic proteins, and the term “active enzyme protein” is defined herein as the amount of catalytic protein(s), which exhibits enzymatic activity. This can be determined using an activity based analytical enzyme assay. In such assays, the enzyme typically catalyzes a reaction generating a colored compound. The amount of the colored compound can be measured and correlated to the concentration of the active enzyme protein. This technique is well-known in the art.

The enzyme(s) may be selected from the group consisting of protease, lipase, cutinase, amylase, carbohydrase, cellulase, pectinase, mannanase, arabinase, galactanase, xylanase, nuclease (DNase, RNase), dispersin, catalase, perhydrolase, and oxidase (such as laccase and/or peroxidase). Preferably, the enzyme(s) is a detergent enzyme selected from the group consisting of protease, lipase, amylase, cellulase, pectinase, mannanase, xylanase, nuclease (DNase, RNase), dispersin, catalase, perhydrolase, and combinations thereof.

The protease may be a serine protease, for example a subtilisin. The amylase may be an alpha-amylase or a glucoamylase. The cellulase may be an endo-1 ,4-beta-glucanase, also referred to as endoglucanase.

The enzyme may be a naturally occurring enzyme of bacterial or fungal origin, or it may be a variant derived from one or more naturally occurring enzymes by gene shuffling and/or by substituting, deleting or inserting one or more amino acids. Chemically modified or protein engineered mutants are included. The particles may comprise at least one enzyme in an amount of 0.1-25% w/w active enzyme protein; preferably in an amount of 0.5-25% w/w, 1-25% w/w, or 5-25% w/w active enzyme protein; and more preferably in an amount of 0.5-20%, 1-20% w/w, or 5-20% w/w active enzyme protein.

The particles may even have a content of active enzyme protein of at least 1% w/w, preferably at least 5% w/w, at least 10% w/w, at least 20% w/w, or at least 30% w/w. Depending on the amount of processing aids used, the amount of active enzyme protein may be up to 50% w/w.

Further embodiments of the invention include:

Embodiment 1. A method for evenly distributing a hydrophobic liquid on the surface of a plurality of particles, comprising

Embodiment 2. The method of the preceding embodiment, where the fluidized bed is a fluidized bed spray coater.

Embodiment 3. The method of any of the preceding embodiments, where the plurality of particles has a Dso in the range of 100-1000 pm

Embodiment 4. The method of any of the preceding embodiments, where the emulsion comprises 1-50% w/w of the hydrophobic liquid.

Embodiment 5. The method of any of the preceding embodiments, where the emulsion comprises 1-35% w/w of the hydrophobic liquid.

Embodiment 6. The method of any of the preceding embodiments, where the emulsion comprises 1-20% w/w of the hydrophobic liquid.

Embodiment 7. The method of any of the preceding embodiments, where the droplet size of the hydrophobic liquid in the emulsion has a Dso in the range of 1-20 pm.

Embodiment 8. The method of any of the preceding embodiments, where the droplet size of the hydrophobic liquid in the emulsion has a Dso in the range of 1-10 pm.

Embodiment 9. The method of any of the preceding embodiments, where the droplet size of the hydrophobic liquid in the emulsion has a Dso in the range of 1-5 pm.

Embodiment 10. The method of any of the preceding embodiments, where the emulsion is sprayed with a droplet size having a Dso in the range of 1-100 pm.

Embodiment 11. The method of any of the preceding embodiments, where the emulsion is sprayed with a droplet size having a Dso in the range of 1-75 pm.

Embodiment 12. The method of any of the preceding embodiments, where the emulsion is sprayed with a droplet size having a Dso in the range of 1-50 pm. Embodiment 13. The method of any of the preceding embodiments, where the emulsion is sprayed onto the plurality of particles for a time sufficient to provide a plurality of particles comprising 0.05-10% w/w of the hydrophobic liquid.

Embodiment 14. The method of any of the preceding embodiments, where the emulsion is sprayed onto the plurality of particles for a time sufficient to provide a plurality of particles comprising 0.05-5% w/w of the hydrophobic liquid.

Embodiment 15. The method of any of the preceding embodiments, where the emulsion is sprayed onto the plurality of particles for a time sufficient to provide a plurality of particles comprising 0.1-5% w/w of the hydrophobic liquid.

Embodiment 16. The method of any of the preceding embodiments, which further comprises spraying a binder onto the plurality of particles.

Embodiment 17. The method of any of the preceding embodiments, which further comprises spraying a polysaccharide binder onto the plurality of particles.

Embodiment 18. The method of any of the preceding embodiments, which further comprises spraying a maltodextrin binder onto the plurality of particles.

Embodiment 19. The method of any of the preceding embodiments, where the hydrophobic liquid has an octanol-water partition coefficient, logP, higher than 0 (zero).

Embodiment 20. The method of any of the preceding embodiments, where the hydrophobic liquid has a solubility in water of less than 1% w/w at 25°C.

Embodiment 21. The method of any of the preceding embodiments, where the hydrophobic liquid has a vapor pressure of less than 1 kPa at 25°C.

Embodiment 22. The method of any of the preceding embodiments, where the hydrophobic liquid is an oil, preferably an edible oil, more preferably a plant oil.

Embodiment 23. The method of any of the preceding embodiments, where the plurality of particles comprises a protein or an enzyme.

Embodiment 24. The method of any of the preceding embodiments, where the plurality of particles are protein or enzyme granules.

Embodiment 25. The method of any of the preceding embodiments, where the plurality of particles comprises 0.1-25% w/w active enzyme protein; preferably 0.5-25% w/w, 1-25% w/w, or 5-25% w/w active enzyme protein.

Embodiment 26. The method of any of the preceding embodiments, where the plurality of particles comprises 0.5-20% active enzyme protein, preferably 1-20% w/w or 5-20% w/w active enzyme protein.

Embodiment 27. The method of any of the preceding embodiments, where the plurality of particles comprises 1-50% w/w of active enzyme protein.

Embodiment 28. The method of any of the preceding embodiments, where the plurality of particles comprises 5-50% w/w of active enzyme protein. Embodiment 29. The method of any of the preceding embodiments, where the plurality of particles comprises 10-50% w/w of active enzyme protein.

Embodiment 30. The method of any of the preceding embodiments, where the plurality of particles comprises 20-50% w/w of active enzyme protein.

Embodiment 31. The method of any of the preceding embodiments, where the plurality of particles is prepared by a procedure, comprising:

(i) spray drying an enzyme liquid to produce an enzyme powder, and

(ii) agglomerating the enzyme powder to produce the plurality of particles.

Embodiment 32. The method of the preceding embodiment, where the enzyme powder is agglomerated in a fluidized bed.

Embodiment 33. A method for producing an enzyme granulate, comprising

(a) spray drying an enzyme liquid to produce an enzyme powder;

(b) agglomerating the enzyme powder to produce enzyme particles having a Dso in the range of 100-2000 pm; and

(c) subjecting the enzyme particles to the method of any of the preceding embodiments.

Embodiment 34. An enzyme granulate produced by the method of any of the preceding embodiments.

Embodiment 35. The enzyme granulate of the preceding embodiment, which exhibits an angle of repose of less than 60°, a Heubach 1 of less than 5 ppm, and/or an “Area under the curve” of less than 5%.

EXAMPLES

Chemicals were commercial products of at least reagent grade.

Gluzyme mono cone BG (“Gluzyme BG”) was obtained from Novozymes. HiPhos BG was obtained from Novozymes.

AMG NA BG was obtained from Novozymes.

Measuring enzyme dust

To measure the amount of released enzyme dust, a scooping box as shown in Figure 1 was used. The design of the box allows dust measurements without any disturbance from external air turbulence sources. A controlled amount of powder is injected/dropped by gravity into a bucket at the bottom in the box (see Figure 1). The standardized gravity injection of powder simulates the pouring of powder after scooping. Thus, the scooping box provides realtime information about how a dust cloud evolves after the powder has been dropped from a certain height. The dust cloud was detected and analyzed by using a dust monitor (DustTrak DRX to Aerosol Monitor 8533) to measure the dust propagation in real time (Figure 2) shows a typical dust profile of a commercial enzyme product, showing a fast increase in the dust concentration after the powder hit the bottom, followed by a settling period. The total amount of detected enzyme dust is found by integrating the measured dust over time ("area under the curve"), which may also be expressed as a percentage of a reference samples.

Measuring the dynamic angle of repose

The material is placed in a cylinder with at least one transparent end. The cylinder is rotated horizontally at a fixed speed and the observer watches the material moving within the rotating cylinder. The effect is similar to watching clothes tumble over one another in a slowly rotating clothes dryer. The granular material will assume a certain angle ("angle of repose") as it flows within the rotating cylinder This method is used to measure the dynamic angle of repose. A powder (plurality of particles) having a dynamic angle of repose of less than 60°, preferably less than 50°, may be considered a free-flowing powder.

Heubach 1

Total dust (dust from the active and the non-active granule ingredients) was determined by the well-known method Heubach Type 1. In the assay, the weighed-out sample amount was placed in a rotating drum containing three integrated blades. A horizontal air stream passed through the drum with a flow at 20 L/min. The airflow led the finest particles further through a non-rotating, horizontal glass column in which the largest particles were separated. The airborne dust was led further and collected on a filter in the filter house. The amount of enzyme dust on the filter was determined by weighing the filter house before and after analysis. The result is expressed as pg of dust released per g of product.

Conditions of Analysis:

Temperature: room temperature

Sample amount: 50.0 g

Air flow: 20 L/min.

Speed of rotation: 30 rpm

Time of analysis: 5 min.

Humidity of air: 30-70% RH

Fiber glass filter: 5 cm GF92

Scooping Box To measure the amount of released enzyme dust, a scooping box as shown in Figure 1 was used. The design of the box allows dust measurements without any disturbance from external air turbulence sources. A controlled amount of powder is injected/dropped by gravity into a bucket at the bottom in the box (see Figure 1). The standardized gravity injection of powder simulates the pouring of powder after scooping. Thus, the scooping box provides real time information about how a dust cloud evolves after the powder has been dropped from a certain height.

The dust cloud was detected and analyzed by using a dust monitor (DustTrak DRX to Aerosol Monitor 8533) to measure the dust propagation in real time Figure 2 shows a typical dust profile of a commercial enzyme product, showing a fast increase in the dust concentration after the powder hit the bottom, followed by a settling period. The total amount of detected enzyme dust is found by integrating the measured dust over time ("area under the curve"), which may also be expressed as a percentage of a reference sample.

EXAMPLE 1

Granulation and subsequent dedusting with emulsion in fluid bed

An enzyme composition was made by agglomeration in a fluid bed. Subsequently an oil- in-water emulsion was sprayed on the granules in the fluid bed. The oil-in-water (dedust) emulsion was prepared as follows.

Dedust emulsion 1

1. Add 25 g FDK (anti-foam agent containing 10% silicone oil-in-water emulsion and emulsifier) to 0.5 L demineralized water,

2. Add slowly 500 mL sunflower oil while mixing with ultra-turrax, and

3. Continue mixing 2 minutes after last oil addition.

Dedust emulsion 2

1. Boil 0.5 L demineralized water,

2. Let it cool to about 80°C before adding the emulsifier,

3. Add 25 g Sodium Stearoyl Lactylate stir to dissolve,

4. Add slowly 250 mL sunflower oil while mixing with Ultra-Turrax, and

5. Continue mixing 2 minutes after last oil addition.

Fluid bed granulation process

The granulation was carried out in a Glatt fluid bed (Procell Lab system with GF3 insert). 1500 g Gluzyme BG enzyme powder was added and agglomerated using a binder solution with 50% w/w Maltodextrin IT21 (DE21) and 50% w/w water. Table 1. Granulation process conditions.

Dedusting After agglomeration, two different dedust emulsions was applied in two separate batches using the process conditions shown in Table 2.

Table 2. Process conditions for spraying the emulsion.

Table 3. Drying conditions after spray addition of the emulsion.

Table 4. Resulting properties of products.

The data in Table 4 show the high dedusting efficiency of applying very small amounts of oil as an emulsion. EXAMPLE 2

Granulation and dedusting of granulate with emulsion

A HiPhos BG enzyme concentrate was sprayed in single stage spray dryer (GEA; FSD spray dryer with internal fluid bed and fines return system) without addition of binder. Table 5. Spray drying process conditions.

The resulting spray dried enzyme powder had a Dso of 113 pm.

Fluid bed granulation process The powder materials in Table 6 were granulated in a Glatt fluid bed (Procell Lab system with GF3 insert) by agglomeration using a binder solution with 50% Maltodextrin IT21 (DE21) and 50% water. Table 6. Granulation powder materials.

Table 7. Granulation process conditions.

Dedusting

After granulation, an oil-in-water emulsion was prepared by adding 0.5 g of Sodium Stearoyl Lactylate (SSL) into 22 g of 60°C warm water under stirring at 400 rpm with an overhead stirrer. After 5 minutes stirring, 2.5 g sunflower oil was slowly added to the stirred SSL/water mix. The final emulsion was sprayed onto the granulated product using the process condition shown in Table 8. The final oil content in the product was 0.2% w/w.

Table 8. Process conditions for spraying the emulsion.

Table 9. Drying conditions after spray addition of the emulsion.

The resulting granulated and dedusted enzyme product had a D50 of 396 pm.

Table 10. Resulting properties of granulated enzyme products.

The data in Table 10 show the high dedusting efficiency of applying as little as 0.2% w/w oil as an emulsion.

EXAMPLE 3 Dedusting of roller compacted enzyme product with emulsion dosing into liquid

An AMG NA BG enzyme powder was granulated in a roller compactor (Alexander Werke; WP 120 Pharma) using a compaction force of 17 kN and a upper sieve size of 1.5 mm. After compaction, an oil-in-water emulsion was prepared by adding 0.5 g of Sodium Stearoyl Lactylate (SSL) into 22 g of 60°C warm water under stirring at 400 rpm with an overhead stirrer. After 5 minutes stirring, 2.5 g sunflower oil was slowly added to the stirred SSL/water mix. The final emulsion was sprayed onto the compacted product using the process conditions in Table 11 in a Glatt fluid bed (Procell Lab system with GF3 insert).

Table 11 . Process conditions for spraying the emulsion.

Table 12. Resulting properties of granulated enzyme products.

The data in Table 12 show the high dedusting efficiency of applying oil as an emulsion, even to a roller compacted granulate.

Claims

1. A method for evenly distributing a hydrophobic liquid on the surface of a plurality of particles, comprising

2. The method of the preceding claim, where the fluidized bed is a fluidized bed spray coater.

3. The method of any of the preceding claims, where the emulsion comprises 1-50% w/w of the hydrophobic liquid; preferably 1-35% w/w, or 1-20% w/w of the hydrophobic liquid.

4. The method of any of the preceding claims, where the droplet size of the hydrophobic liquid in the emulsion has a Dso in the range of 1-20 pm; preferably in the range of 1-10 pm, or in the range of 1-5 pm.

5. The method of any of the preceding claims, where the emulsion is sprayed with a droplet size having a Dso in the range of 1-100 pm; preferably in the range of 1-75 pm, or in the range of 1- 50 pm.

6. The method of any of the preceding claims, where the emulsion is sprayed onto the plurality of particles for a time sufficient to provide a plurality of particles comprising 0.05-10% w/w of the hydrophobic liquid; preferably 0.05-5% w/w, or 0.1-5% w/w of the hydrophobic liquid.

7. The method of any of the preceding claims, which further comprises spraying the plurality of particles with a binder; preferably the binder is a polysaccharide such as maltodextrin.

8. The method of any of the preceding claims, where the hydrophobic liquid has an octanolwater partition coefficient, logP, higher than 0 (zero).

9. The method of any of the preceding claims, where the hydrophobic liquid has a solubility in water of less than 1 % w/w at 25°C.

10. The method of any of the preceding claims, where the hydrophobic liquid has a vapor pressure of less than 1 kPa at 25°C.

11. The method of any of the preceding claims, where the hydrophobic liquid is an oil, preferably an edible oil, more preferably a plant oil.

12. The method of any of the preceding claims, where the plurality of particles comprises protein or enzyme; preferably the plurality of particles comprises 1-50% w/w of active enzyme protein.

13. The method of any of the preceding claims, where the plurality of particles is prepared by a procedure comprising

(i) spray drying an enzyme liquid to produce an enzyme powder, and

(ii) agglomerating the enzyme powder to produce the plurality of particles.

14. The method of the preceding claim, where the enzyme powder is agglomerated in a fluidized bed.

15. An enzyme granulate produced by the method of any of the preceding claims, which exhibits an angle of repose of less than 60°, a Heubach 1 of less than 5 ppm, and/or an “Area under the curve” of less than 5%.