WO1996038057A1

WO1996038057A1 - Method of producing a yeast extract useable in foodstuffs, where undesirable flavouring agents in the extract have been removed

Info

Publication number: WO1996038057A1
Application number: PCT/FI1996/000326
Authority: WO
Inventors: Göran Hyöky; Marja-Leena Sarkki; Matti Tylli
Original assignee: Cultor Ltd.
Priority date: 1995-06-02
Filing date: 1996-05-31
Publication date: 1996-12-05
Also published as: FI952726A; FI952726A0; AU5823596A; EP0871374A1

Abstract

The invention relates to a method of producing a yeast extract useable in foodstuffs by degrading the yeast hydrolytically, preferably with enzymes, by recovering the soluble substances and by purifying the resultant solution with a polymeric adsorbent. The invention also relates to a method of removing bitter substances, yeastiness and/or other undesirable flavouring agents from a yeast extract by treating the yeast extract with a polymeric adsorbent. The yeast extract may be a brewer's yeast extract or a baker's yeast extract. The invention also relates to a resultant yeast extract and its use as a flavouring enhancer or flavouring or a component of the same in foodstuffs.

Description

Method of producing a yeast extract useable in foodstuffs, where undesirable flavouring agents in the extract have been removed.

The invention relates to a method of producing and treating a yeast extract to remove unpleasant odour and flavouring components from the yeast extract while maintaining the desirable flavouring agents in the yeast extract. The method of the invention improves the quality of the final yeast extract product such that it can be used e.g. as a flavouring enhancer or a flavouring in food industry. The invention also relates to a yeast extract produced by the method and to use of the yeast extract as a flavouring enhancer or flavouring or a component of the same in food industry.

The method of the invention is based on the use of polymeric adsorbents. The method is particularly well-suited for brewer's yeast extracts, and it can also be applied to yeast extracts of other origin, such as baker's yeast extracts.

The most significant palatable components of a yeast extract are nucleotides, peptides and amino acids, all of which influence the taste profile of the yeast extract and its capacity to intensify the flavour of different food products, such as meat, chicken, fish, crustacean or cheese based products. However, a yeast extract produced from brewer's yeast also comprises unpleasant flavouring components that impart a bitter and yeasty flavour. These unpleasant flavouring components are primarily derived from a hop extract used in brewing, the extract containing bitter substances that adsorb to the surface of the yeast. The bitter substances, the most significant of which is isohumulone (structurally an α-resin acid) , restrict the use of a brewer's yeast extract as a foodstuff, so they must be removed to produce a passable final product. The use of a baker's yeast extract is in some cases hindered by its too distinctive yeasty flavour and odour and by its bitterness. The polymeric adsorbent treatment according to the invention reduces the yeasty odour and flavour and the bitterness.

To produce a brewer's yeast extract of food product quality, some of the bitter substances are conventionally removed by treating the brewer's yeast with alkali, whereby the isohumulones are dissolved and can be washed off. Alkali wash of yeast is described e.g. in Process Biochemistry (1966) no. 9, p. 316, and it is also mentioned in U.S. Patent 4,097,614 (West, S.M., Kraft Foods Ltd.) . In alkali wash, however, some of the valuable proteins of yeast are lost in the soluble phase. Bitter substances can also be removed from the yeast cell tissue by supercritical extraction. The use of supercritical extraction is described in EP Bl 0,041,723 (Eisenbach, W. , Studiengesellschaft Kohle GmbH) . Brewer's yeast is thereby treated with C0₂, ethane, ethylene and/or propane under hypercritical conditions of pressure and temperature, and the gas loaded with bitter substances is passed through an adsorbent (activated carbon) to purify the gas.

U.S. Patent 2,149,306 (Millar, J.H. , Arthur Guinness Son and Company) teaches the use of autolysis for producing a soluble food extract from brewer's yeast. After the autolysis, the yeast extract is purified by treating it with activated carbon. Activated carbon is known to effectively remove bitter substances from a yeast extract, but it has the clear disadvantage that it also adsorbs some of the desirable nucleotides and proteins and that it is difficult to filter. It should also be noted that powdery activated carbon can be used, in principle, only once, whereas granulated activated carbon can be regenerated, although the regeneration must be performed outside the process.

To eliminate the drawbacks involved in the use of activated carbon, it has been suggested that brewer's yeast should be treated with porous material produced e.g. from an activated carbon-PVA-iron-oxide mixture (U.S. Patent 4,097,614, West, S.M., Kraft Foods Ltd.) . The adsorbent used can be regenerated e.g. with lye. U.S. Patent 3,443,969 (Nakajima, N. et al . ,

Takeda Chemical Industries Ltd.) teaches a method for preparing a yeast extract useable in foodstuffs by treating Torula yeast with the growth medium of a microbial culture derived from Trametes sanquinea and subsequently purifying the resultant extract with diatomaceous earth. From the publication it also appears that yeast extracts can be purified with suitable ion exchange resins to remove colour and unpleasant odour. Process Biochem (1966) , no. 9, p. 313 to 317 teaches removal of bitter substances from a brewer's yeast extract by adsorption, precipitation and ion exchange.

A yeast extract can be produced by hydrolysing yeast cell tissue with acid or enzymes. The enzymes may be derived from the yeast cell tissue itself or they may be specific enzymes, proteases, ribonucleases and deaminases that have been added. Enzymatic production of yeast extracts is described e.g. in U.S. patents 3,914,450 (Robbins, E.A. et al . , Anheuser-Busch Inc.) , 3,443,969 (Nakajima, N. , Takeda Chemical Industries Ltd.) and 5,288,509 (Potman, R.P., Lever Brothers Company) , in EP Al 299,078 (Harada, S. et al . , Kohjin Co.), and in Japanese patent application JP 57-219695 (Takeda Chemical Industries) . In the present invention, 'yeast extract' is a solution obtained by degrading a yeast cell tissue with enzymes present in the yeast itself (autolysis) , with added enzymes or acid under specific conditions, and by separating the components extracted from the degraded yeast cell mass to water.

A brewer's yeast extract is a product obtained in the above manner using as a starting material a residual yeast obtained in a beer fermentation process and separated therefrom.

A baker's yeast extract, in turn, is a product produced in the above manner using, baker's yeast, e.g. Saccharomyces cerevisiae, as yeast.

The invention relates to a method of producing a yeast extract suitable for use in foodstuffs, the method comprising the following steps :

(a) hydrolytic degradation of yeast

(b) recovery of soluble substances, and

(c) purification of the resultant solution with a polymeric adsorbent.

The hydrolytic degradation (a) can be performed enzymatically either by the action of the enzymes of the yeast itself (autolysis) , or with specifically added enzymes, or by acid hydrolysis. The method can also comprise an alkali wash prior to the hydrolytic treatment (a) . To obtain the final product, the product purified with an adsorbent is also usually dried, using e.g. spray drying.

The hydrolytic degradation (a) is advantageously performed enzymatically. In the enzyme treatment, prior art can be applied (see e.g. above- mentioned U.S. Patents 3,914,450, 3,443,969 and 5,288,509, EP Al 299,078, and Japanese Patent Application JP 57-219695) . The degradation usually comprises one or more enzyme treatments. It is possible to conduct e.g. only a protease treatment or e.g. a three-step enzyme treatment comprising a protease treatment, ribonuclease treatment and deaminase treatment (see e.g. EP Al 299,078) . The protease treatment breaks the cell walls of yeast, whereby RNA and amino acids are released. The ribonuclease treatment splits the RNA of yeast cells into different nucleotides, and the deaminase treatment converts adenosine mononucleotide (AMP, adenosine monophosphate) into inosine mononucleotide (IMP, inosine mono¬ phosphate) , which is a desirable nucleotide component with respect to flavour. In addition to the inosine mononucleotide, another desirable flavouring nucleotide component in yeast is guanosine mononucleotide (GMP, guanosine monophosphate) .

A specific example for an enzyme treatment is a treatment with protease, 5' -phosphodiesterase and 5'- adenylic acid deaminase (Japanese patent application JP 57-219695) . In step (b) of the method according to the invention, i.e. recovery of soluble substances obtained from the hydrolytic treatment, it is also possible to apply the technique known per se. A soluble fraction that comprises the desirable components but also comprises non-desirable bitter substances can be separated from an insoluble fraction e.g. by separation.

In an alternative preliminary treatment, i.e. alkali treatment, of the method according to the invention, it is also possible to apply the technique known per se (see e.g. above-mentioned Process. Biochem. (1966) , no. 9, p. 313 to 317, and EP Al 299,078) . An alkali wash can be performed e.g. with a NaOH solution. It removes some of the bitter substances but also some of the desirable proteins. If an alkali wash is used in combination with an adsorbent treatment according to the invention, a product containing but few bitter substances is obtained. When the alkali wash is left out, i.e. replaced with an adsorbent treatment, a corresponding product is obtained but the adsorbent capacity is naturally lower, since the amount of removable bitter substances per dry solids is greater.

Step (c) of the method according to the invention, i.e. purification of the resultant yeast extract, is performed with polymeric adsorbents.

The invention also relates to a method of treating a yeast extract useable in foodstuffs by contacting it with a polymeric adsorbent. In particular, the invention relates to a method of removing bitter substances, yeastiness and other undesirable flavouring agents from a yeast extract by contacting the yeast extract with a polymeric adsorbent that binds bitter substances and other undesirable flavouring agents but does not bind peptides, amino acids or nucleotides to a significant extent .

According to the invention, it is possible to use as polymeric adsorbents any polymer based adsorbents that bind undesirable bitter substances to a significant extent but do not bind essential quantities of desirable peptides, amino acids and nucleotides that provide the taste profile. With regard to the action of the adsorbent, important parameters are its pore size and specific surface. Essential characteristics are also its water retention capacity, porosity and controlled pore size distribution.

Especially good results have been obtained by the use of non-ionic macroporous polymeric adsorbents or slightly basic macroporous polymeric adsorbents. The purpose of the ionic groups, if present, is to improve the hydrophilic properties of the adsorbent.

The pore size of the polymeric adsorbents is in the range of 25 to 1000 A (2.5 to 100 nm) and preferably 200 to 500 A (20 to 50 nm) and the specific surface thereof is in the range of 150 to 1500 m²/g.

The polymeric adsorbent is preferably an adsorbent having a polystyrene skeleton and optionally comprising weakly basic groups, e.g. a styrene/divinyl- benzene copolymer based adsorbent. One such adsorbent is Amberlite XAD-16 (by Rohm & Haas) . It is also possible to use an adsorbent having an acryl skeleton and optionally comprising weakly basic groups, e.g. an acryl/divinylbenzene based adsorbent. One such adsorbent is Amberlite XAD-7 (by Rohm & Haas) . It is also possible to use an adsorbent having a phenolformaldehyde polymer skeleton and optionally comprising weakly basic groups. One such adsorbent is Amberlite XAD 765 (by Rohm & Haas) . With regard to the structure, Amberlite XAD-16 is a non-ionic macroporous crosslinked polystyrene that is commercially available as 0.3 to 1.2 mm beads, has a water retention capacity of 64 to 68%, pore size of 200 to 250 A (20 to 25 nm) , specific surface of at least 750 m²/g and porosity of 0.58 to 0.63 ml pores/ml of beads.

The adsorbent treatment is usually carried out in conventional columns. It can be carried out at a temperature of 5 to 100°C, preferably at 10 to 25°C. The pH may vary from 1 to 14, preferably it is from 4 to 6. The dry solids content of the yeast extract used may be 0.1 to 70%, preferably 2 to 6%. The flow rate at which the yeast extract is passed through the adsorbent column may vary from 0.1 to 70 resin volume/h (RV/h) , preferably it is from 5 to 40 RV/h, most preferably from 10 to 20 RV/h. The adsorbent column may be regenerated with NaOH and subsequently neutralized with HCl, but a good result is also obtained by using only NaOH regeneration. As compared with the conventionally used activated carbon, e.g. the following advantages are achieved with the polymer adsorbent treatment according to the invention: losses of desirable flavouring agents are negligible, it is easy to use in continuous processes and can be regenerated in position as part of the process, bitter substances are removed effectively, and the meat taste of the yeast product is intensified. If the alkali wash is left out altogether and the debittering is conducted entirely by the adsorbent treatment, the yield of flavouring components of the yeast extract is higher, since dissolving of proteins caused by the alkali wash is hereby avoided.

It was unexpected that a treatment with the above-mentioned polymeric adsorbents removed the undesirable bitter flavouring components from the yeast extract but maintained the desirable components, such as nucleotides (especially guanosine monophosphate and inosine monophosphate nucleotides) , peptides and amino acids, very well. The invention also relates to a yeast extract product produced by the above methods. The yeast extract product may be a brewer's yeast extract or a baker's yeast extract.

A yeast extract produced in accordance with the invention can be used as a flavouring enhancer or a flavouring in different foodstuff applications, optionally in combination with other flavouring enhancers and flavourings. It can be used as such or mixed e.g. with salt, dextrose or maltodextrine to provide a flavouring enhancer for finished and semifinished food products, processed meat, spice mixtures and snacks. The yeast extract according to the invention can also be used as a flavouring together with e.g. baking aromas in corresponding food products. It can also be used as an intermediate when different flavourings and baking aromas are prepared, the yeast extract usually undergoing Maillard reactions during the preparation.

The invention thus also relates to the use of a yeast extract as a flavouring enhancer or flavouring or a component of the same in foodstuffs, such as finished and semifinished food products, processed meat, spice mixtures and snacks. Example 1A The starting yeast extract (brewer's yeast extract) can be produced as follows:

A brewer's yeast suspension (20% d.s., pH 6.3) obtained as a side fraction of brewer's yeast is heated (300 g based on dry solids) to a temperature of 80 to 100°C about 30 minutes and subsequently cooled to 50°C.

At this temperature, 1.5 g of protease Protin PC-10

(Daiwa Kasei K.K.) is added to the yeast suspension, and the enzyme is allowed to effect for 10 hours, while the suspension is stirred. After the reaction, the temperature of the suspension is raised to 80°C for 30 minutes, after which the suspension is cooled to 65°C. After this, 0.2 g of enzyme Ribonuclease P (Amano Pharmaceutical Ltd.) is added to the suspension, and the suspension is stirred slowly for three hours. The suspension is cooled to 45°C, and 0.2 g of enzyme Deamizyme (Amano Pharmaceuticals Ltd.) is added to it, after which stirring is continued at this temperature for two hours . The insoluble material is removed from the suspension e.g. by centrifugation to produce a brewer's yeast extract for an adsorbent treatment. Example IB

The produced brewer's yeast extract that contained 2.7% of dry solids was treated with different adsorbents and ion exchange resins by passing 3000 ml of the yeast extract solution (pH 5.7, temperature 20 to 25°C) at a flow rate of 600 ml/h through a column (500 ml, diameter 2.5 cm) packed with 200 ml of test materials mentioned in table 1, i.e. regenerated adsorbent (Optipore, Amberlite XAD-16) , ion exchange resin (Amberlite IRA 68, Amberlite IRA 958) or granulated activated carbon (Chemviron SA) . Of the test materials, Optipore, Amberlite XAD-16 and Amberlite IRA 68 were regenerated with 4% NaOH (2.5 RV) , and Amberlite IRA 958 with 10% NaCl (2.5 RV) , and subsequently washed with water (10 RV) .

From the outlet of the column, 400 ml fractions were collected for organoleptic testing. Organoleptic tests were carried out with a 2.5% yeast extract solution the pH of which had been adjusted to 5.5 and to which 0.8% of NaCl had been added.

A summary of the test and analysis results obtained during the debittering cycle (370 g d.s./l litre of resin) with different test materials is presented in table 1. It is noted that bitterness was significantly reduced with adsorbents Optipore, Amberlite XAD-16 and activated carbon Chemviron CPG. The losses of nucleotides were particularly small with Amberlite XAD-16 (-OH) . Table 1

Debittering of a brewer's yeast extract with adsorbents. Cycle length 370 g d.s./l litre of resin

Bitter¬ Meat Loss of Nuclectide loss ness taste d.s., % % d.s.

CMP UMP GMP IMP

Untreated +++ * brewer's yeast product

Adsorbent + 28 17 20 55 46 Optipore (-0H), (Dow Chemicals)

Adsorbent + ** 24 <2 5 4 7 Amberlite XAD-16 (-OH) , (Rohm & Haas)

Activated carbon + ** 36 64 65 77 73 CPG, (Chemviron SA)

Weakly basic ++ * 11 <2 29 74 33 anion exchanger Amberlite IRA 68 (-OH) , (Rohm & Haas)

Strongly basic +++ *+ 4 <2 40 63 64 anion exchanger as adsorbent Amberlite IRA 958 (-C1) , (Rohm & Haas)

+++ very bitter ***strong meat taste

++ bitter ** clear meat taste

+ slightly bitter * slight meat taste

CMP = cytidine monophosphate UMP = uridine monophosphate GMP = guanosine monophosphate IMP = inosine monophosphate

Optipore = weakly basic adsorbent with polystyrene skeleton

Amberlite XAD-16 = non-ionic adsorbent with polystyrene skeleton

Amberlite IRA 68 = weakly basic anion exchanger with polyacrylic skeleton containing tertiary amino groups

Amberlite IRA 958 = strongly basic anion exchanger having a polyacrylic skeleton and containing quaternary ammonium groups Table 2 shows the results of a test in which the treatment was performed otherwise in the same way as above but the pH of the yeast extract solution supplied to the column was 4.5 and Optipore and XAD-16 were neutralized after NaOH regeneration with HCl.

Table 2

Debittering of a brewer's yeast extract with adsorbents. Cycle length 972 g d.s./l litre of resin

Bitter¬ Meat Loss of Nucleotide 1 OSS ness + taste * d.s., %

CMP UMP GMP IMP

Untreated +++ ** brewer's yeast extract

Optipore + *** 12.5 17 <2 33 <2 (-OH+-C1)

Amberlite + +** 7 21 1 <2 <2 XAD-16 (-OH+-C1)

Amberlite +++ * 12 66 85 99 72 IRA 68 (-0H)

Chemviron CPG ++ 19 62 41 30 22

+, * estimation of bitterness and meat taste, see table 1

The table shows that polymeric adsorbents removed bitterness more effectively than e.g. powdery activated carbon or ion exchange resins. The reduction of bitterness intensified the meat taste evidently because the components concealing the taste were removed. The losses of dry solids and nucleotides were clearly smaller when polymeric adsorbents were used. The losses of those nucleotide components that are the most valuable with respect to flavour, i.e. GMP and IMP, were negligible when adsorbent Amberlite XAD-16 was used.

Example 2 A brewer's yeast suspension (10% d.s.) obtained as a by-product in brewing was treated with alkali by adjusting its pH to 9 and was stirred for 30 minutes at 25°C. The suspension was subjected to centrifugation to produce an alkali washed brewer's yeast suspension (23% d.s.) , which was washed three times with water to remove the alkali. A brewer's yeast extract that contained 3.3% of dry solids was produced from the suspension and used in the tests that followed. For debittering, the extract was treated with adsorbents Amberlite XAD-16 and Amberlite XAD 765 by passing 23 1 of the yeast extract solution (pH 5.7, temperature 20 to 25°C) at a flow rate of 5 1/h through a column packed with 500 ml of a regenerated adsorbent. The adsorbents were regenerated for removal of bitter substances by regenerating with 4% NaOH (2.5 RV) , washing with water (10 RV) , neutralizing with 5% HCl (0.5 RV) and washing with water (8 RV) .

During the run, 5 1 fractions were collected, analyzed for dry solid and nucleotide contents and subjected to an organoleptic test (evaluation of bitterness and meat taste) . To determine the cycle length, the bitterness of the fractions was determined by an organoleptic taste test as in example 1. Table 1 is a summary of the results obtained from the whole collected cycle (23 1) . Table 3

Debittering of an alkali washed brewer's yeast extract with different adsorbents. Cycle length 1500 g d.s./l litre of resin.

Bitter¬ Meat Loss of Nucleotide loss (% ness + taste * d.s., % d.s.)

CMP UMP GMP IMP

Untreated 2.3 2.2 baker' s yeast extract

Untreated 3.5 1.6 brewer's yeast extract

Amberlite XAD- 2 2.3 3 <2 <2 <2 <2

16 (-0H+-C1)

Amberlite XAD 2.5 2.3 2 <2 <2 <2 <2

765 (-0H+-C1)

+ \5 = very bitter * 5 = strong meat taste 13 = bitter 3 = clear meat taste ll = not bitter II = no notable meat taste

Amberlite XAD 765 = a slightly basic adsorbent with phenolformaldehyde skeleton containing few tertiary amino groups

The results show that both tested adsorbents reduce bitterness significantly. The losses of nucleotides and dry solids are also minimal.

Example 3 (pilot plant run)

An alkali washed brewer's yeast extract was produced in the same way as in example 2. The extract contained 3.5% of dry solids. Removal of bitter substances and other undesirable components was carried out by passing 88 1 of the yeast extract solution (pH 5.7, temperature 20 to 25°C) at a flow rate of 10 1/h through a column packed with 700 ml of adsorbent Amberlite XAD-16. The adsorbent had been regenerated with 4% NaOH (1.7 1) , washed with water (6 1) , neutralized with 5% HCl (0.35 1) , and washed with water (7 1) . During the run, 10 1 fractions were collected and subjected to an organoleptic test to evaluate their bitterness. On the basis of these preliminary taste tests, an 88 1 cycle was collected. It was then analyzed for dry solids, amino acids and nucleotides and the results were compared with the supply solution. The collected cycle was evaporated and dried with a Niro spray drier (manufactured by Niro A/S, Denmark) . A control product was produced in a similar manner by evaporation and drying a brewer's yeast extract that had not been treated with an adsorbent. The brewer's yeast extracts (1.6% d.s., 0.4% NaCl, pH 5.5) were subjected to organoleptic tests. The relative bitterness of the solutions was also determined by a spectrophotometric method in accordance with AOAC 965.21. The results are presented in table 4.

The debittering effect of Amberlite XAD-16 is evident, and the bitterness and meat taste of the treated brewer's yeast extract improved. The losses of nucleotides, amino acids and peptides were minimal.

Table 4

Debittering of alkali washed brewer's yeast extract with adsorbent Amberlite XAD- 16. Cycle length 3000g d.s./l litre of resin.

+, * estimation of bitterness and meat taste, see table 3

Example 4

A baker's yeast extract was produced from a commercially available baker's yeast suspension (23% d.s.) by the use of enzymes in the same way as in example 1A. The extract contained 5.8% of dry solids. Removal of bitter substances and other undesirable components was carried out by passing 50 1 of the yeast extract solution at a flow rate of 10 1/h (pH 5.7, temperature 12°C) through a column packed with 700 ml of adsorbent Amberlite XAD-16. The adsorbent had been regenerated with 4% NaOH (1.7 1) , washed with water (5 1) , neutralized with 5% HCl (0.35 1) and washed with water (7 1) . The 50 1 fraction of a baker's yeast extract passed through the column was analyzed for the dry solids content, amino acids, nucleotides and bitterness. Organoleptic estimation of bitterness was conducted on a 2% solution with a pH of 5.5. The effect of the adsorbent treatment in the light of the results measured is presented in table 5. The number of components imparting an unpleasant flavour ('yeasty flavour') and odour for a baker's yeast extract was reduced and the meat taste was intensified when the extract was treated with adsorbent Amberlite XAD-16. Further, no significant losses of nucleotides or amino acids seemed to result from the treatment .

Table 5

Bitterness Meat taste Yeastiness Loss of d.s. Amino acid Nucleotide OSS ( %) + * o (%) loss (%)

CMP UMP GMP IMP

Baker's yeast 2.3 1.8 3.2 extract

Baker's yeast 1.3 2.3 1.7 2 1-2 <2 <2 <2 <2 extract treated with Amberlite XAD-16

00

+, * estimation of bitterness and meat taste, see table 3

o \5 = strongly yeasty J3 = clearly yeasty '1 = no notable yeastiness

The following table 6 presents a summary of the properties of the adsorbents of the invention and the ion exchange resins (comparison) used in the above examples for debittering a yeast extract . Table 7 presents a summary of the test results of debittering a yeast extract .

Table 6. Summary of adsorbents and ion exchange resins used for debittering a yeast extract

Functional Matrix Specific Pores A Pore volume Capacity Type group surface m²/g ml/ml ml/ml meq/ml

Adsorbents

Amberlite XAD- non-ionic polystyrene 750 200-250 0.6 macroporous

16 DVB

Rohm S Haas

Amberlite XAD-7 non-ionic polyacryl 450 450-500 0.55 macroporous Rohm S Haas

Amberlite XAD slightly basic phenol- 150-250 200-500 0.35 >0.15 macroporous 765 Rohm & Haas tertiary amine formaldehyde NJ

Optipore Dow slightly basic polystyrene 800 25-50 0.5 macroporous Chemicals tertiary amine

Stronαl . basic anion exchange resin

Amberlite IRA strongly basic polyacryl 0.8 macroporous

958 quaternary

Rohm & Haas ammonium

Table 7. Summary of tests of debittering a yeast extract

Functional group Matrix Losses of Losses of Bitterness d. s . , % nucleotides

Adsorbents

Amberlite XAD-16 non-ionic polystyrene DVB (1)24 <5 + Rohm & Haas (2)7 <2 + (3)- <2 + (4)4 <2 -66%

Amberlite XAD 765 slightly basic phenol- (3)2 <2 + Rohm S Haas tertiary amine formaldehyde

Optipore Dow slightly basic polystyrene (1)28 20-50 + Chemicals tertiary amine (2)12 2-30 + t

Activated carbon (1)36 60-70 + CGP, Chemviron (2)19 20-40 ++ _jilightlγ basic anion exchange resin

Amberlite IRA 68 , tertiary amine polyacryl (1 ) 11 30-70 ++ Rohm & Haas ( 2 ) 12 70-90 +++

+++ very bitter ( ) reference to examples

++ bitter

+ not bitter

Use examples

A yeast extract produced in accordance with the above examples can be used for the preparation of flavouring enhancers and flavourings. Flavouring enhancer compositions comprising 45 to 100%, preferably 70 to 90%, of a yeast extract according to the invention, 0 to 30%, preferably 10 to 20%, of NaCl, and 0 to 20% of other components, such as sugar, were produced. Flavouring compositions comprising 1 to 80%, preferably 10 to 50%, of a yeast extract according to the invention, 5 to 60%, preferably 20 to 40%, of baking aromas, 0 to 20% of NaCl, and 0 to 40% of other components, such as sugar, maltodextrine, lactose and mixed spices, were also produced.

The above flavouring enhancer and flavouring compositions were used in the production of finished and semifinished food products, processed meat, spice mixtures and snacks. In the organoleptic tests conducted, the taste of the food products containing a yeast extract according to the invention was found excellent.

The foregoing general discussion and experimental examples are intended to be illustrative of the present invention and are not to be considered as limiting. Other variations within the spirit and scope of the present invention are possible and will present themselves to those skilled in the art.

Claims

1. A method of producing a yeast extract suitable for use in foodstuffs, c h a r a c t e r - i z e d by the method comprising the following steps :

(a) hydrolytic degradation of yeast

(b) recovery of soluble substances, and

(c) purification of the resultant solution with a polymeric adsorbent .

2. A method according to claim 1, c h a r ¬ a c t e r i z e d in that the hydrolytic degradation (a) is performed enzymatically.

3. A method according to claim 1, c h a r a c t e r i z e d in that the method also comprises an alkali wash prior to the hydrolytic treatment (a) .

4. A method according to any one of the preceding claims, c h a r a c t e r i z e d in that the method also comprises a drying step after the adsorbent treatment (c) .

5. A method according to any one of claims 2 to 4, c h a r a c t e r i z e d in that the enzyme treatment contains a protease treatment .

6. A method according to any one of claims 2 to 4, c h a r a c t e r i z e d in that the enzyme treatment contains a protease, ribonuclease and deaminase treatment.

7. A method of treating a yeast extract useable in foodstuffs by contacting it with an adsorbent, c h a r a c t e r i z e d in that the adsorbent is a polymeric adsorbent .

8. A method of removing bitter substances, yeastiness and/or other undesirable flavouring agents from a yeast extract by contacting the yeast extract with an adsorbent, c h a r a c t e r i z e d by the use of a polymeric adsorbent that binds bitter substances and other undesirable flavouring agents but does not bind peptides, amino acids or nucleotides to a significant extent.

9. A method according to any one of claims 1 to 8, c h a r a c t e r i z e d in that the polymeric adsorbent is a non-ionic or slightly basic macroporous polymeric adsorbent.

10. A method according to any one of claims 1 to 9, c h a r a c t e r i z e d in that the polymeric adsorbent is an adsorbent having a polystyrene skeleton and optionally containing weakly basic groups.

11. A method according to claim 10, c h a r a c t e r i z e d in that the adsorbent with a polystyrene skeleton is a styrene/divinylbenzene copolymer based adsorbent .

12. A method according to claim 11, c h a r a c t e r i z e d in that the adsorbent is Amberlite XAD-16.

13. A method according to any one of claims 1 to 9, c h a r a c t e r i z e d in that the polymeric adsorbent is an adsorbent having an acryl skeleton and optionally containing weakly basic groups.

14. A method according to claim 13 , c h a r a c t e r i z e d in that the adsorbent with an acrylic skeleton is an acryl/divinylbenzene copolymer based adsorbent .

15. A method according to claim 14, c h a r a c t e r i z e d in that the adsorbent is Amberlite XAD-7.

16. A method according to any one of claims 1 to 9, c h a r a c t e r i z e d in that the polymeric adsorbent is an adsorbent having a phenolformaldehyde polymer skeleton and optionally containing weakly basic groups.

17. A method according to claim 16, c h a r a c t e r i z e d in that the adsorbent is Amberlite XAD-765.

18. A method according to any one of the preceding claims, c h a r a c t e r i z e d in that the yeast extract is a brewer's yeast extract or a baker's yeast extract.

19. A method according to any one of claims 1 to 18, c h a r a c t e r i z e d by preparing a flavouring enhancer product.

20. A method according to any one of claims 1 to 18, c h a r a c t e r i z e d by preparing a flavouring product .

21. A yeast extract, c h a r a c t e r i z e d in that it is prepared by a method according to any one of claims 1 to 18.

22. A yeast extract according to claim 21, c h a r a c t e r i z e d in that it is a brewer's yeast extract or a baker's yeast extract.

23. Use of a yeast extract according to claim

21 or 22 as a flavouring enhancer or flavouring or a component of the same in foodstuffs, such as finished and semifinished food products, processed meat, spice mixtures and snacks.

24. Use according to claim 23, c h a r a c ¬ t e r i z e d in that the yeast extract is used in meat, chicken, fish, crustacean and cheese based products.