GB2171585A - Yeast extract food flavour - Google Patents

Abstract

Process for preparing a food flavour comprises inactivating yeast and carrying out enzymatic degradation of biopolymers in conjunction with fermentation with micro-organisms. Preferably the enzymatic degradation is carried out with more than one enzyme either simultaneously or sequentially.

Description

SPECIFICATION Food Flavours The invention relates to a process for the preparation of a food flavour by enzymatic treatment of yeast.

Such processes are known in the art. Yeast autolysates, which are prepared by subjecting yeast to degradation by the endogeneous enzyme material of yeast, are wellknown as food additives.

The autolysis can be induced by incubating the yeast cells at a higher temperature by addition of organic solvents, such as ethyl acetate ortoluene, by using an increased salt concentration or a combination of these methods. This results in an inactivation of the yeast cells but the enzymes of the yeast material remain active and are available for the actual degradation.

The main conversion taking place during autolysis is the degradation of proteins to peptides and amino acids. The autolysis thus obtained usually have a typical bitter and yeast-like taste. A further disadvantage of these autolysates is that they contain 3'-ribonucleotides because the endogeneous ribonuclease converts RNA into 3'ribonucleotides, which make no contribution to the flavour.

It is also known in the art to improve the enzymatic degradation of yeast by first degrading the cell walls with an appropriate enzyme which results in an increase in the yield of autolysate (cf.

US-A-3,682,778, Kyowa Hakko Kogyo).

Furthermore, it is known to increase the yield by using proteolytic enzymes in conjunction with the endogeneous enzymes (cf. NL-A-7907402, Standard Oil Co). Finally NL-A-7601962 (nestle) discloses the enzymatic degradation of inactivated yeast.

According to the present invention an improved food flavour is prepared by carrying out the enzymatic degradation of inactivated yeast in conjunction with fermentation. The organoleptic properties of the flavour material thus obtained are improved as there is no bitter taste and no, or a less pronounced, yeast-like note. Moreover, organic acids like lactic acid, succinic acid, etc. also improve the taste.

Suitable yeast starting materials belong to the group consisting of Saccharomyces species, Kluyveromyces species, Candida species, Torula species, Fusarium species and Zymomonas species.

Preferred are Saccharomyces, Kluyveromyces, Candida and Torula species. More in particular, yeasts like Saccharomyces cerevisiae, Kluyveromyces lactis, Kluyveromyces fragilis, Kluyveromyces marxianus, Candida utilis may be used.

Prior to the enzymatic degradation of the yeast, the yeast is inactivated, e.g. by heat treatment at a temperature between 70 and 150"C for 5 to 120 minutes. Inactivation by cooking usually requires an aqueous suspension with a dry matter content up to 30%. Inactivation is, of course, also possible by means of the addition of chemicals or e.g. by radiation.

Once the yeast has.been inactivated, both enzymatic degradation and fermentation are carried out in any sequence dr simultaneously, provided that a carbon source is available for fermentation.

The enzymatic degradation of the inactivated yeast is carried out by means of suitable enzyme preparations of bacterial, vegetable, yeast or animal origin. The enzyme preparation used preferably has more than one of the following activities: 1. Proteolytic Activity Preferably one or more of the following enzymes are used: Pancreatin, Trypsin (from Porcine or bovine pancreatic tissues), Bromelain (from Ananas comosus/bracteatus), Ficin, Molsin, Chymotrypsin, Papain (from Ca rica papaya), Chymo-papain (from Carica papaya), Pepsin (from Porcine gastric mucosa), Rennin or proteases from Bacillus subtilis, Asp erglllus oryzae, Penicillium dupontii, Streptomyces griseus, Mucor miehel/pusfilus, hog kidney, etc.

Dependent on the particular enzyme used, the incubation is carried out at a pH between 2 and 10 and a temperature between 20 and 80"C. Pepsin e.g.

hasan optimal activity at pH 2-3, proteasefrom Streptomyces griseus an optimum at pH 9--10 and papain is still active at 7Q800C.

2. Cell Wall Degradation Activity Beta-glucanase derived from Bacillus subtilis/ licheniformis, Penicillium emersonii, Aspergillus niger/oryzae.

The incubation is usually carried out at a temperature between 20 and 70"C and a pH between 3and7.

3. Amylase or glycogen degrading activity, e.g.

alpha- and beta-amylase, derived from Bacillus subtilis, Aspergillus spp, which enzymes are generally used in incubations at pH 4-8 and at a temperature of 2070 C.

4. RNA Degrading Activity Leading to 5'ribonucluotides Use of e.g. phosphodiesterase, e.g. obtained from malt rootletsorfungal extracts. These are used at pH 3-9 and at a temperature of 20--70"C.

5. Lipolytic Activity Pancreatin or pancreatic lipase which is incubated at pH 10 and at a temperature between 20 and 70"C.

The enzymatic degradation step of the present invention usually combines several of these enzymatic activities. This can be achieved by simultaneous incubation with a number of enzymes.

Also a plurality of incubations with different enzymes is possible, often under different conditions of pH and temperature.

There are, of course, also a number of enzyme preparations commercially available which combine several enzymatic activities, such as pancreatin, etc.

When a plurality of enzymatic actions is used, the incubation may lead to the formation of amino acids, peptides, mono- and disaccharides, 5'ribonucleotides and fatty acids.

It is preferred to use such a plurality of enzyme that proteolytic activity is combined with RNA degradation. More preferred is to include also cell wall degrading enzyme and/or lipolyticenzyme.

In accordance with the present invention the enzymatic degradation is used in conjunction with fermentation with micro-organisms. Preferably enzymatic degradation is followed by fermentation so that saccharides are converted inter alia into organic acids like lactic acid, succinic acid, etc. It is also advantageous to carry out enzymatic degradation simultaneously with fermentation.

Fermentation by micro-organisms is usually carried out at a pH from 4.5 to 7.5 and at a temperature of 20--65"C, for a period ranging between 4 hours and 14 days. In the practice of the present invention, micro-organisms are applied which are generally used in the preparation of milk products, meat and meat products, fermented vegetables, fermented beverages, bread, pickles and sauces, such as: Lactic acid bacteria (e.g.) Lactobacillus acidophilus, L. delbrueckii, L casei; L. plantarum, L.

fermentum, L. brevis, L. buchneri.

Lactic streptococci (e.g.) Streptococcus lactis, Str.

cremoris, Str. diacetylactic, Pediococcus pentosaceus, P. cerevisiae, Leuconostoc gracile, L.

cremoris.

Yeast, e.g. Saccharomyces rouxii, S. cerevisae, as well as combinations of the above-mentioned microorganisms.

The yeast extract obtained in accordance with the present invention typically comprises: 2045% (w.w*) of protein material (130% of peptides and 520% of free amino acids); 0.56% of guanosine-5'-monophosphate; 20% of lactic acid.

*calculated on dry extract Once enzymatic degradation and fermentation have been carried out, further downstream processing of the resulting product is recommendable, such as removal of insoluble material (filtration of centrifuging), concentration (evaporation of water, spray-drying, oven drying, drum drying or freeze-drying, optionally in the presence of a carrier like maltodextrin) or pasteurization e.g. for 510 minutes at 800C. Any sequence is feasible.

The food flavour thus obtained can be used as such to impart or reinforce the flavour of foodstuffs, optionally in combination with other flavouring materials. The combination can be physical mixing or chemically reacting to form reaction flavours.

The invention also comprises the yeast extract prepared by the processes described above.

One embodiment of the present invention is therefore a process for flavouring foodstuffs by incorporating in the foodstuff a flavour as disclosed hereinbefore. More in particulartheflavour material is used to improve the flavour of soups, meat products, instant gravies, margarine, frying fat, drinks, bakery products, cheese, confectionery products and the like. The amount of flavour used in the foodstuffs varies widely but usually ranges between 0.1 and 10% (calculated as dry yeast extract flavour on the foodstuff ready for consumption). Preferably these amounts range between 0.15 and 5%.

EXAMPLE 1 0.67 kg of Saccharomyces cerevisiae (baker's yeast ex Gist Brocades, Delft, The Netherlands, with a dry matter content of 30%) were mixed with 0.33 kg of water. The slurry thus obtained was boiled at 100 Cfor 10 minutes, subsequently cooled to 60"C and the pH was adjusted to pH 4.0 by the addition of aqueous phosphoric acid.

2.2 g of MKC cellulase P 4000 (ex Miles Kali Chemi GmbH & Co Kg, Hannover-Kleefeld, Germany) having an activity of 4,000 CU/g were added and the mixture was stirred for 16 hours at 60"C. The slurry was then heated to 1 OO"C for 10 minutes, cooled to 50"C and the pH was adjusted to 7.0 by the addition of some aqueous sodium hydroxide.

3.0 g of Brew-N-zym GPGL (ex Jan Dekker, Wormerveer, The Netherlands) having a proteolytic activity of 100 N U/ml were then added and the mixture was stirred for 3 hours at 50"C. The mixture was then heated to 1000C for 5 minutes and 0.5 kg of water were added and the slurry was cooled to 40"C, after which the pH of the slurry was adjusted to 5.8 by the addition of phosphoric acid.

Now 0.5% (v/v) of a pre-culture of Lactobacillus buchneriwere added. This pre-culture was a dense preculture of the organism which grew at a logarithmic rate on a conventional medium. The slurry was stirred with this micro-organism for 16 hours at 40"C.

Subsequently the insoluble matter was removed from the slurry by filtration, the filtrate was pasteurized at 80"C for 20 minutes and concentrated and a paste with a dry matter content of 60% was obtained. This product was completely watersoluble and had a low sodium chloride content.

Upon organoleptic comparison with yeast autolysate, the product according to the present invention showed a better meat-like taste and, moreover, the yeast-like note, which so often occurs with yeast autolysates, was absent.

EXAMPLE 2 0.2 kg of Kluyveromyces lactis (ex Bel Industries, Paris, France) were mixed in a reaction vessel with 0.7 kg of water. The slurry thus obtained was heated to 100 C for 20 minutes and cooled to 50"C and the pH was adjusted to 4.5 by the addition of aqueous phosphoric acid.

2.0 g of MKC hemicellulase (ex Miles Kali Chemi GmbH & Co KG, Hannover-Kleefeld, Germany, having an activity of 2,500 HCU/g) were then added together with 5 g of malt rootlets (ex Export Mouterij "Nederland", Wageningen, The Netherlands, dry matter content of 94%) and the mixture was stirred for 16 hours at 60"C. The pH of the slurry was then adjusted to 5.0 by the addition of some aqueous sodium hydroxide.

0.8 g of papain (ex Merck & Co, Darmstadt, Germany, with an activity of 30,000 USP-U/mg) and 0.1 g of cystein were added, after which the mixture was stirred for 3 hours at 60"C. The slurry was then heated to 100"C for 10 minutes and 0.33 kg of water were added. The slurry was cooled to 45"C and the pH was adjusted to 5.8 by the addition of some aqueous sodium hydroxide.

Now 0.2% (v/v) of a pre-culture of Lactobacillus delbrueckiiwere added. This dense pre-culture of the micro-organism grew at a logarithmic rate on a conventional medium. The slurry was then stirred for 16 hours at 40"C.

Subsequently the solid material was separated by centrifuging and the clear solution thus obtained was pasteurized and concentrated. Spray-drying on a conventional carrier yielded a yellowish powder that was microbially stable.

EXAMPLE 3 0.2 kg of Torula yeast (ex Attisholz AG, Luterbach, Switzerland, dry matter content 98%) were mixed in a reaction vessel with 0.8 kg of water. The slurry thus obtained was heated to 1 OO"C for 40 minutes and cooled to 55"C and the pH was adjusted to 4.0 by the addition of aqueous phosphoric acid.

2.0 g of MKC Cellulase P 4000 (ex Miles Kali Chemi GmbH & Co KG, Hannover-Kleefeld, Germany, with an activity of 4,000 CUIT) were added and 1.0 g of Bromelain (ex Sigma Chemie GmbH, Taufkirchen, West Germany, with an activity of 2,000 U/g), after which the mixture was stirred for 8 hours at 55"C.

The slurry was then cooled to 400C and 0.25 kg of water were added and the pH was adjusted to 5.8.

Now 0.8% (v/v) of a pre-culture of Lactobacillus plantarum were added. This pre-culture was a dense pre-culture, which grew at a logarithmic rate. The slurry was stirred for 16 hours at 40"C and was then cooled to 250C.

Subsequently 0.1 % (v/v) of a fresh densely grown pre-culture of Saccharomyces rouxiiwere added at 25"C and the slurry was stirred for 48 hours at that temperature. The slurry thus obtained was then processed as described in Example 2 and a yellowish powder was obtained.

EXAMPLE 4 0.2 kg of Saccharomyces cerevisiae (ex Nedalco N.V., Bergen op Zoom, The Netherlands, dry matter content 97%) were mixed in a reaction vessel with 0.8 kg of water. The slurry thus obtained was heated to 100"C for 10 minutes and subsequently cooled to 50"C and the pH was adjusted to 8.0 by the addition of aqueous sodium hydroxide.

1.0 g of pancreatin (ex Merck, Darmstadt, Germany, having an activity of 30,000 FIP-U/g [lipase]) were added to the slurry and this was stirred for 20 hours at 60"C. The pH of the slurry was then adjusted to 4.0 by the addition of some aqueous phosphoric acid.

10 g of Brew-N-enzym Filtranase L 5 (ex Jan Dekker, Wormerveer, The Netherlands, having an activity of 9,500 Endo - beta - 1,4 - glucanase U/ml) were added together with 0.8g officin (ex Sigma Chemie GmbH, Taufkirchen, West Germany, activity 1.5 U/mg protein) and stirred for 6 hours at 60"C. The slurry was then heated to 1 OO"C for 10 minutes and the slurry was cooled to 40"C and the pH was adjusted to 5.8 by the addition of some aqueous sodium hydroxide.

Now 0.5% (v/v) of a pre-culture of Streptococcus diacetylactis were added. This was a densely grown pre-culture which grew at a logarithmic rate on a conventional medium. Together with this fermentation 3.0 g of Brew-N-enzym/GPGL (ex Jan Dekker, Wormerveer, The Netherlands) were added.

Subsequently the slurry was stirred for 16 hours at 40"C.

The slurry was then processed as described in Example 2 and a fine yellowish powder was obtained.

EXAMPLE 5 A meat flavour composition was prepared by mixing ofthefollowing ingredients: 200 g of yeast extract paste obtained according to Example 1 lOg glucose 2 9 cystein 3 9 thiamine-HCI salt 2g tallow The mixture was heated for 90 minutes whilst refluxing. After cooling to 40"C, 200 g of maltodextrin and 200 g of water were added. The solution thus obtained was spray-dried.

The spray-dried powder, when added to an 0.5% aqueous solution of cooking salt in an amount of 1.5%, imparted an excellenttaste of boiled beef, which closely resembled the taste of authentic beef broth.

EXAMPLE 6 2.5 g of a spray-dried yeast extract as prepared according to Example 4 were added to the following dry soup composition: 10 g sodium chloride 2.5 g monosodium glutamate 6 9 tallow 20 g vermicelli 4 g dried chopped onion 1.5 g dried chopped carrots 0.25 g of a mixture of herbs and spices The total composition was taken up in 1 litre of water and boiled for 20 minutes. An expert tasting panel found the soup rounded off, savoury and sweet beef-like.

EXAMPLE 7 2.0 g of a spray-dried yeast extract as described in Example 3 were added to the fish sauce composition: 8 g skimmed milk powder 10 g wheat flour 1 g sodium chloride 1 g monosodium glutamate 80 g water After heating the composition to 100"C, a sauce was obtained having a full flavoured fresh taste, which sauce was used successfully in the ratio of 2 parts of sauce to 1 part of boiled codfish.

EXAMPLE 8 0.1 part of spray-dried yeast extract as prepared according to Example 2 was added to the aqueous phase of a margarine, which aqueous phase consisted for 5% of water 10% of skimmed milk 1% of sodium chloride.

This mixture was adjusted to pH 5.6. The fat phase consisted of 10% hardstock obtained by interesterification of hydrogenated soybean oil (melting point 43"C) and 42% palm oil (melting point 58"C) and 90% liquid sunflower oil and worked into a margarine in the usual way. When used as a table margarine, a cool cream-like impression was obtained. When used as a frying margarine, at 140"C a sweet flavoured taste developed reminiscent of dairy butter.

Claims (15)

1. A process for the preparation of a food flavour by degrading yeast with enzymes, characterized in that yeast is inactivated and that enzymatic degradation of biopolymers is carried out in conjunction with fermentation with micro organisms.

2. A process according to Claim 1, characterized in that subsequently downstream processing takes place.

3. A process according to Claim 1 or 2, characterized in that the yeast starting material belongs to the group consisting of Saccharomyces, Kluyveromyces, Candida and Torula.

4. A process according to Claim 1, 2 or 3, characterized in that inactivation is effected by heat treatment.

5. A process according to any of the preceding Claims, characterized in that proteolytic enzyme is used in the enzymatic degradation.

6. A process according to any of the preceding Claims, characterized in that cell wall degradating enzyme is used in the enzymatic degradation.

7. A process according to any of the preceding Claims, characterized in that glycogen-degrading enzyme is used in the enzymatic degradation.

8. A process according to any of the preceding Claims, characterized in that RNA degrading enzyme, optionally after incorporation of additional RNA in the substrate, is used in the degradation, resulting in the formation of 5'-ribonucleotides.

9. A process according to any of the preceding Claims, characterized in that lipolytic enzyme is used in the enzymatic degradation.

10. A process according to any of the preceding Claims, characterized in that, after the enzymatic degradation, fermentation by micro-organisms is carried out.

11. A process according to any of Claims 1-9, characterized in that enzymatic degradation and fermentation by micro-organisms are carried out simultaneously.

12. A process according to any of the preceding Claims, characterized in that in the fermentation such micro-organism is used that produces lactic acid.

13. A process according to any of Claims 1-11, characterized in that in the fermentation a yeast is used.

14. A yeast extract obtained by a process as described in any of the preceding Claims.

15. A process for flavouring foodstuffs, characterized in that a yeast extract according to Claim 14 is used.