METHOD FOR INHIBITING YEAST ACTIVITY

Abstract

The combination of EGCG and a derivative of a basic amino acid has been found to be an effective anti-yeast agent in acidic food. The present invention relates to a method for controlling or preventing the growth of yeast in acidic food (i.e. with a pH between 2 and 6) comprising adding to said food a) epigallocatechin gallate (EGCG) and b) a derivative of a basic amino acid, and/or a salt thereof, as an anti-yeast agent. The present invention further relates to a composition for addition to food and to an acidic food comprising said composition.

Claims

1. A method for controlling or preventing the growth of yeast in a food having a pH between 2 and 6 comprising adding to said food a combination of a) epigallocatechin gallate (EGCG) and b) a derivative of a basic amino acid selected from the group consisting of a polymer of a basic amino acid and an ester of a basic amino acid alpha-amide, and/or a salt thereof, as an anti-yeast agent.

2. The method according to claim 1 wherein epigallocatechin gallate is added to the food as a green tea extract.

3. The method according to claim 1, wherein the polymer of a basic amino acid is polylysine.

4. The method according to claim 3 wherein the polylysine is -polylysine.

5. The method according to claim 1, wherein the ester of a basic amino acid alpha-amide is lauric arginate.

6. The method according to claim 1, wherein epigallocatechin gallate is added to the food in a concentration between 0.0001 wt. % and 2 wt. %.

7. The method according to claim 1, wherein the derivative of a basic amino acid is added to the food in a concentration between 0.00001 wt. % and 1 wt. %.

8. The method according to claim 1, wherein the food has a pH between 3 and 5.

9. The method according to claim 1, wherein the food is a beverage.

10. The method according to claim 1, wherein the yeast is Candida albicans, Saccharomyces cerevisiae and/or Zygosaccharomyces bailii.

11. A composition for addition to a food comprising a) epigallocatechin gallate and b) both lauric arginate and polylysine.

12. The composition of claim 11 wherein the weight ratio between a) and b) is between 0.01a:1b and 5000a:1b.

13. A food having a pH between 2 and 6 comprising a) epigallocatechin gallate and b) both lauric arginate and polylysine.

14. The food of claim 13 comprising a) in a concentration between 0.0001 wt. % and 2 wt. % and b) in a concentration between 0.00001 wt. % and 1 wt. %.

Description

EXAMPLE 1

Inhibition of yeasts.

[0041] The Green tea extract EGCG 50 with a 53 wt. % of EGCG, was purchased from Layn, Lijiang, China. -Polylysine (50 wt. % of polylysine) was purchased from Chisso, Japan. LAE, Minerat-N (40 wt. %) was purchased from Vedeqsa, Spain.

[0042] Candida albicans was isolated from a commercial beverage, Saccharomyces cerevisiae (CBS 2190) and Zygosaccharomyces bailiff (CBS 6708) were obtained from CBS (Centraalbureau voor Schimmel-cultures).

[0043] A) Determination of the Minimal Inhibitor Concentration.

[0044] Yeast cultures were grown in liquid medium (per liter: 5 gram filtered Malt Extract from Oxoid Ltd., England, 40 gram glucose and 5 gram Bacto Peptone from Becton Dickinson, USA, at pH 3.5 prepared according to the manufacturer instructions) in screw-capped tubes for at least 48 hours at 25 C.

[0045] For the determination of the MIC, liquid medium was prepared as described above with increasing amounts of inhibitor.

[0046] 200 l of each inhibitor-comprising medium was transferred to a panel of a sterile 96-well Microtiter plate. Completed well plates were stored at 4 C. until further use. For the inoculation of the inhibitor-containing liquid media 5 l of a 72 to 84 hours grown culture was used. The optical density (OD) for every composition was measured 96 hours after inoculation. The MIC values obtained are shown in table 1.

TABLE-US-00001 TABLE 1 EGCG -polylysine LAE Yeast MIC (ppm) MIC (ppm) MIC (ppm) C. Albicans 9000 >40* >70* S. cerevisiae 5000 30-80 30-80 Z. bailii 2000 >40* >70* *highest amount tested

[0047] B) Combination Tests.

[0048] Inhibition of yeast was evaluated for combinations of EGCG and polylysine or LAE.

[0049] Yeast cultures were grown in model beverage which contained per litter of demineralised water: 40 g of sucrose, 0.35 g of apple flavor (Givaudan), 8.3 g of apple juice concentrate (Gargill) and 1 g of citric acid. The pH was about 3.5. Cultures were grown in screw-capped tubes for at least 48 hours at 25 C.

[0050] The tests combining two components were carried out in sterile 96-well Microtiter plates. Model beverage was prepared as described above with increasing amounts of two different inhibitors. The concentrations of each inhibitor were presented in 8 equal concentration steps that ranged from 0 to 1-2 times the estimated MIC value of particular yeast for a particular inhibitor. 200 l of each medium was transferred to a panel of a sterile 96-well Microtiter plate. Completed well plates were stored at 4 C. until further use. For the inoculation of this test 5 l of a 72 to 84 hours grown culture was used. The OD for every composition was measured 96 hours after inoculation. The results are shown in table 2.

TABLE-US-00002 TABLE 2 EGCG -polylysine LAE Yeast (wt. %) (wt. %) (wt. %) Maximum OD C. Albicans 0.47* C. Albicans 0.07 0.40* C. Albicans 0.002 0.30 C. Albicans 0.0005 0.32 C. Albicans 0.07 0.002 <0.05 C. Albicans 0.07 0.0005 <0.05 Z. bailii 0.38* Z. bailii 0.07 0.28* Z. bailii 0.002 0.38 Z. bailii 0.0005 0.40 Z. bailii 0.07 0.0005 <0.05 Z. bailii 0.07 0.002 <0.05 S. cerevisiae 0.32* S. cerevisiae 0.07 0.28* S. cerevisiae 0.001 0.19 S. cerevisiae 0.07 0.001 <0.05 *average of two experiments