WO2003070930A1 - Novel applications of gels that contain immobilised yeasts - Google Patents

Abstract

The invention relates to novel applications of gels that contain immobilised yeasts. The aforementioned gels are used to control the browning of drinks which happens over time. The gels comprise a matrix of natural alginate or carrageenan polysaccharide as the base of the gel and immobilised yeast cells in the structure of said matrix. The gels thus formed can be used to correct the colour of a drink that has already browned and to prevent any change in the colour of a drink that can brown over time. The invention is suitable for use in the food industry sector.

Description

NEW APPLICATIONS OF GELS CONTAINING IMMOBILIZED LEAVES

TECHNICAL FIELD OF THE INVENTION

The present invention falls within the sector of the food industry.

More specifically, the present invention relates to new applications of gels containing immobilized yeasts in their constitution, to control the undesirable browning of certain beverages in the food sector, such as juices and wines.

STATE OF THE PRIOR ART OF THE INVENTION

The browning of raw materials or processed liquid foodstuffs of plant origin is an alteration process that depreciates the quality of them very strongly. This problem originates as a consequence of the presence, in this type of liquids, of a large family of compounds, called polyphenols, which, through a series of natural chemical reactions, lead to products of complex and pronounced brown composition. Since these reactions progress over time, the products afflicted with this problem lose their original color, turning to brown tones that the consumer rejects.

The undesirable evolution of the commented color is of a variable severity depending on the type of product. Thus, in products consumed in the short term, the color varies to a small extent, changes unnoticed by most consumers. However, in products intended for medium or long-term consumption, such as some juices, wines, etc., the problem is clearly noticeable, causing a bad appearance of the food product. In particular, in industries such as white wine, this alteration is the cause of one of its greatest economic losses, since some time has passed since the commercialization of the beverage, companies are forced to withdraw unsold units from the market. To avoid bad brand image that gives excessive color increase. At present, the methods used to control the browning of this type of products in the medium and long term are generally based on chemical methods.

In particular, to reduce the brown color index of a beverage before packaging, polyvinyl polypyrrolidone (PVPP) and activated carbon are commonly used, which are highly effective for this purpose.

These materials are usually used to correct the color of the starting liquid product in order to reduce it to the lowest possible hue, and thereby lengthen the period of time in which said browning reaches an undesirably high level, in which the product can be rejected by the consumer or have to be removed from the market by the manufacturer. This implies the chemical treatment of the starting liquid with the corrective agent, so that it captures the colored or susceptible products, prior to packaging and distribution, thereby lengthening the storage period before the browning level makes rejectable the product.

Although this technique allows to improve the situation of these drinks achieving a period of greater consumption time and lower economic losses, the use of this type of correctors also presents certain drawbacks. . First, the reduction in color intensity is greater the higher the applied dose of the corrective agent. The problem is that in parallel these compounds tend to negatively modify the taste and smell of the beverage to which they are applied. Secondly, it cannot be forgotten that these corrective agents are chemical products whose use in the food industry is increasingly controversial. In fact, the global trend in this sector is aimed at obtaining food in the most natural way possible, limiting or avoiding those treatments with chemical compounds that can interact with food products. Finally, it should be taken into account that these color correction treatments prior to packaging have a merely temporary efficacy. Certainly, browning is diminished as a result of the treatment, but it cannot be avoided that the color continues to evolve towards brown tones once the beverage is packaged.

In summary, the current treatments to control the browning of beverages during storage only allow the problem to be alleviated but cannot be resolved as it would be desirable, and also suffer from the drawbacks outlined above.

The present inventors have studied the problem in depth in order to find an alternative solution that overcomes the limitations and disadvantages of current techniques. As a result of several studies, they have found that certain natural galas, including in their constitution immobilized yeast cells, have proved especially useful for the control of browning over time of packaged beverages, especially juice, wines, etc.

This finding has allowed them to complete the present invention, which is described in detail in the following sections of this specification.

DETAILED DESCRIPTION OF THE INVENTION

The present invention, as indicated in its statement refers to new applications of gels containing immobilized yeasts.

The gels used in the present invention are constituted by a matrix of polysaccharides in which yeast cells have been immobilized.

In principle, any natural polysaccharide could be used as the base of the gel, but an alginate or a K-carrageenan are especially preferred for the purposes of the present invention. As regards yeast, the Saccharomyces cerevisiae species that is well known in the food sector is especially preferred. For the preparation of these gels containing the immobilized yeast, a procedure known in the sector is used that includes the following operations: a) preparation of a homogeneous mixture in water of the polysaccharide and the yeast cells in a ratio between 2: 1 and 1 : 2, heating if necessary to keep the gel in a liquid state, b) solidification of the gel containing the yeast cells in its constitution, to immobilize them, c) forming the gel containing the immobilized yeast cells to the desired form .

According to the above procedure, when the gel is an alginate, for example, sodium alginate, the mixture obtained in step (a) can be solidified by dripping it on a solution of calcium chloride, in which the drops solidify forming beads (pellets), whose diameter ranges between 1 and 2 mm.

On the other hand, when the gel is a carrageenan, for example, sodium K-carrageenan, it is necessary to heat the mixture of step (a) to 70-90 ° C to keep the gel in a liquid state. For solidification of the mixture, it can be poured into a container of the desired shape forming sheets of the desired thickness (usually of the order of 1 to 3 mm), which are allowed to cool to solidify. Then, the sheets thus obtained can be immersed in a solution of potassium chloride to increase their stiffness. Finally, the solidified gel sheet containing the immobilized yeast cells is cut into pieces of the desired shape and size. The gels thus obtained by immobilizing yeast cells in a matrix of polysaccharides are especially useful within the food sector, to control the browning of beverages during storage, especially juices, wines, etc. In particular, they have application in the treatments of correction and protection of the color of the drinks during their elaboration and / or before their bottling, and during their storage. Specifically, the use proposed by the invention for said gels has two fundamental aspects, namely:

- Decrease in the color of drinks that have a tendency to brown over time, such as white wine (corrective action).

- Delay in the appearance of brown compounds in this type of beverage, extending its optimal consumption period for a longer time (preventive action).

In accordance with the foregoing, the present invention additionally offers an alternative method to those of the prior art of color reduction and / or prevention of its increase in drinks with a tendency to browning, using the gels described above.

Since both yeasts and polysaccharides used in gels are acceptable natural products in the food sector, and the process of treating beverages with them does not imply the use of chemical reagents that could alter the beverage, this aspect of The invention has the additional advantage of fully adapting to current regulations in the food sector.

EMBODIMENTS OF THE INVENTION

The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.

EXAMPLE 1: Obtaining an alginate gel containing immobilized yeast cells.

A homogeneous mixture containing sodium alginate and Saccharomyces cerevisiae cells is prepared in water with relative proportions between the two components of 1.5: 1. The mixture formed is poured into a container and is propelled by a peristaltic pump to circulate through a rubber at whose outlet a drip of the gel occurs in a liquid state. These drops fall on a solution of 0.1 M CaCl2 which causes solidification of the gel in the form of spheres (pellets). The diameter of the gel beads, between 1 and 2 mm, is controlled according to the size of the nozzle located at the outlet. EXAMPLE 2: Obtaining a K-carrageenan gel containing immobilized yeast cells.

A homogeneous mixture containing sodium K-carrageenan and Saccharomyces cerevisiae cells is prepared in water, with relative proportions between the two components of 1.5: 1. The mixture is heated to 70-90 ° C to keep the gel in a liquid state, and it is poured onto a rectangular container with variable height, which results in sheets of different thicknesses (1 to 3 mm). It is allowed to cool to solidify the gel, increasing its stiffness by immersing the sheets in a 2.5% potassium chloride solution. Finally, the gel sheet is cut into cylinders with a diameter between 4 and 5 mm. EXAMPLE 3: Evaluation of the gels of the invention as corrective agents for white wine browning.

In order to demonstrate the effectiveness of the gels of the invention as color-correcting agents in white wines, a white wine with an absorbance at 420 nm of approximately 0.160 a.u. (It should be clarified that the wavelength of 420 nm is a wavelength commonly used in the sector for the determination of the brown color of the wines. The higher the absorbance value, the greater the browning of the beverage).

The color correction procedure was carried out by adding the pellets of the alginate-yeast gel and K-car agenate-yeast onto the wine. Constant stirring was applied for one hour, in order to favor the contact of the gel with the browning products of the wine and, after that time, the absorbance at 420 nm was measured to compare it with the initial one mentioned above.

The means and standard deviations of the results obtained in triplicate for the two products used, in different relative proportions, are shown below: Table 1

Gel Type Proportion Dose of Absorbance at 420 relative product nm after the addition of 1: 1 lOOg / L 0,115 + 0.009 carrageenan-yeast 1: 2 lOOg / L 0.105 + 0.001 yeast alginate-1: 1 120g / L 0.125 + 0.003 alginate-yeast 1: 2 120g / L 0.137 + 0.001

It should be clarified that an absorbance value of 0,170 u.a. corresponds to a white wine of "fine type" whose browning level is very close to the rejection limit for distribution and consumption, and that has an absorbance value of 0,100-0,110 CU. It corresponds to a freshly bottled fine white wine, which has not yet had time to undergo a browning process. Observing the results presented in Table 1 above, it can be seen that the treatment of wine with both gels in the indicated proportions produces a decrease in absorbance as a result of a reduction in the concentration of brown products present in the wine, which remain retained in the gel.

It can also be seen that carrageenan gels are more effective as agents that correct the browning level of wine, since with a lower dose than the alginate gel equivalent they cause a greater decrease in absorbance.

EXAMPLE 4: Evaluation of the gels of the invention as preventive agents of white wine browning.

To demonstrate the efficacy of the gels of the invention as browning agents in white wines, a white, fine-type, commercial wine that was stored at room temperature (20-22 ° C) has been used as a starting sample. 70 cL bottles. To each bottle were added, in doses of 100 g / L carrageenan-yeast gel pellets obtained in a 2: 1 ratio. As before, browning control was carried out by absorbance measurements at 420 nm throughout storage. The following table 2 shows, at the time of filling the bottles and at three months, the absorbance values (ua) at 420 nm for the wine in the presence and absence of the gel.

Table 2

0 months 3 months

Without gel 0.103 + 0.001 0.130 + 0.003 With gel 0.103 + 0.001 0.095 + 0.002

As can be seen, at the time of bottling, the wine had an optimum absorbance (around 0,100 a.), Increasing this value after three months to 0,130 a.a. in bottles that did not contain gel. However, in the presence of the gel, the value remained practically around the initial figure.

If it were desired to reduce the time required to carry out the test, the wine browning process could be accelerated by increasing the storage temperature. In this line, the test was repeated using as a starting sample the same wine with the same gel in the same proportions, but storing it at 35 ° C (instead of at room temperature) for 27 days. The results are shown in the following Table 3.

Table 3

0 months 27 days

Without gel 0.103 + 0.001 0.185 + 0.008 With gel 0.103 + 0.001 0.124 + 0.005

As can be seen, after 27 days of storage, the wine kept in the absence of gel exceeded the reasonable limits of consumption as far as browning is concerned. The wine stored with gel also browned, although in a very moderate way for the conditions in which the experience was conducted. Keep in mind that 0.124 ua are very close to 0.130 ua obtained after 3 months of storage at room temperature, which suggests that the presence of gel in contact with the stored wine can substantially increase the consumption time, acting effectively as a browning preventive agent.

Claims

I. Use of gels containing immobilized yeasts in their structure, to control the browning of beverages over time. 2. Use of gels according to claim 1, characterized in that said gels are essentially constituted by a matrix of a natural polysaccharide as the base of the gel, and yeast cells immobilized in said natural polysaccharide matrix. 3. Use of gels according to claim 2, characterized in that said polysaccharide is an alginate. 4. Use of gels according to claim 3, characterized in that said polysaccharide is sodium alginate. 5. Use of gels according to claim 2, characterized in that said polysaccharide is a K-carrageenan. 6. Use of gels according to claim 5, characterized in that said polysaccharide is sodium K-carrageenan. 7. Use of gels according to claim 1, characterized in that said yeast cells are Saccharomyces cerevisiae cells. 8. Use of gels according to claim 1, characterized in that the ratio of polysaccharide to yeast is between 2: 1 and 1: 2. 9. Use of gels according to claims 1 to 8, characterized in that said gels are prepared by intimately mixing said natural polysaccharide matrix and said yeast cells, allowing the mixture to solidify and forming the product obtained in particles of the desired size. 10. Use of gels according to claim 9, characterized in that said gel is formed in the form of pellets. II. Use of gels according to claim 10, characterized in that the diameter of said pellets is between 1 and 2 mm. 12. Use of gels according to claim 9, characterized in that said gel is formed in the form of sheets, which are subsequently cut into pieces. 13. Use of gels according to claim 12, characterized in that said sheets have a thickness of 1-3 mm. 14. Use of gels according to the preceding claims, characterized in that said beverage is selected from juices and wines. 15. Use of gels according to claim 14, characterized in that said wine is a white wine. 16. Use of gels according to claims 14 and 15, characterized in that said browning control involves the color correction of a beverage that has already acquired a certain brown color, by treating it with particles of said gels. 17. Use of gels according to claims 14 and 15, characterized in that said browning control implies the prevention of the development of brown color in a beverage with a natural tendency to browning during the passage of time, by bringing said beverage into contact with particles of said gels during storage.