Short Communication - (2015) Volume 4, Issue 2

Distribution of a kokumi peptide, γ-Glu-Val-Gly, in various fermented foods andthe possibility of its contribution to the sensory quality of fermented foods

Kuroda M1*, Miyamura N1, Mizukoshi T2, Miyano H2, Kouda T2 and Eto Y2
1Institute of Food Research & Technologies, Ajinomoto Co., Inc., Kanagawa 210-8681, Japan
2Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-8681, Japan
*Corresponding Author: Kuroda M, Institute of Food Research & Technologies, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-8681, Japan Email:

Abstract

A potent kokumi peptide, γ-glutamyl-valyl-glycine (γ-Glu-Val-Gly), was identified and quantified in various fermented foods using high performance liquid chromatography-tandem mass spectrometry (LC/MS/MS). This peptide was present in fermented seasoning such as fish sauces, soy sauces, and fermented shrimp pastes. Among the brewed alcoholic beverages, γ-Glu-Val-Gly was detected in beer. In addition, the content of γ-Glu-Val-Gly positively correlated with the quality grade of dark-colored soy sauce (correlation coefficient ρ=0.810, p<0.05). These results suggest that γ-Glu-Val-Gly is widely distributed in fermented foods and that the content of this peptide can be an indicator of sensory quality of fermented foods.

Keywords: γ-Glu-Val-Gly; γ-Glutamyl-valyl-glycine; Kokumi; Fermented food; Fish sauce; Soy sauce; Shrimp paste; Beer; LC/MS/MS

Introduction

Recent studies have indicated that Kokumi substances such as glutathione are perceived through the calcium-sensing receptor (CaSR) in humans [1,2]. These studies have confirmed that glutathione can activate human CaSR, and that several γ-glutamyl-peptides can also activate the CaSR, and these peptides possess the characteristics of Kokumi substances, which modify the five basic tastes, especially sweet, salty and umami, when they are added to basic taste solutions or food, even though these substances have no taste themselves at the concentrations tested [1,3,4]. Among these Kokumi peptides, γ-Glu- Val-Gly has been reported to be a potent Kokumi peptide [1]. In our studies, the distribution of γ-Glu-Val-Gly in various foods was investigated. Because the contents of γ-Glu-Val-Gly in foods were very low, a new method for the determination and quantification of this peptide using LC/MS/MS followed by derivatization with 6- aminoquinoyl-N-hydroxysuccinimidyl-carbamate (AQC) reagent was developed. In the present review, the presence and quantities of γ-Glu- Val-Gly in various fermented foods is examined. In addition, possibility of the contribution of γ-Glu-Val-Gly to the sensory quality of fermented foods and the possible biosynthetic pathway of this peptide in foods is also discussed.

Determination and quantification of a Kokumi peptide, γ-Glu-Val- Gly, in various fermented foods.

Because preliminary tests indicated that γ-Glu-Val-Gly was not detected in almost raw foods, but was detected in several fermented foods, the contents of γ-Glu-Val-Gly in various fermented foods were investigated. The content of this peptide in 20 brands of commercial fish sauce from Southeast Asia, East Asia and Europe was quantified. Amongst the 20 brands tested, 15 brands of fish sauce contained γ- Glu-Val-Gly at concentrations ranging from 0.4 to 12.6 mg/L [5]. In addition, γ-Glu-Val-Gly was distributed in commercial Japanese soy sauces at concentrations ranging from 1.5 to 6.1 mg/L [6]. Furthermore, commercial fermented shrimp paste condiments from Southeast Asia contained this peptide at concentrations ranging from 0.9 to 5.2 mg/kg [7]. Next, the contents of γ-Glu-Val-Gly in various brews including wine, rice wine (sake), and beer were analyzed. The analyses indicated that γ-Glu-Val-Gly was present in all of the beer samples (n=8) at concentrations ranging from 0.08 to 0.18 mg/L [8]. However, the peptide was not detected in any of the wine or rice wine samples [8]. These results indicate that γ-Glu-Val-Gly is widely distributed in fermented foods such as fish sauces, soy sauces, fermented shrimp paste, and beer.

Correlation between γ-Glu-Val-Gly Content and Food Grade Quality

To clarify the contribution of γ-Glu-Val-Gly to the sensory quality of various fermented foods, the correlation between the content of the peptide and index of the quality was investigated. In the case of commercial soy sauce, for example, the Spearman’s rank correlation test indicated that the content of γ-Glu-Val-Gly was positively correlated with the quality grade of commercial soy sauce (correlation coefficient ρ=0.810, p<0.05). These results suggest that γ-Glu-Val-Gly contributed to the sensory quality of fermented foods.

Conclusion

A Kokumi peptide, γ-Glu-Val-Gly is widely distributed in various fermented foods. In addition, the content of this peptide has been positively correlated with the quality grade of soy sauces and fish sauces, suggesting that γ-Glu-Val-Gly contributes to the sensory quality of fermented foods.

References

Citation: Kuroda M, Miyamura N, Mizukoshi T, Miyano H, Kouda T, Eto Y (2015) Distribution of a Kokumi Peptide, -Glu-Val-Gly, in Various Fermented Foods and the Possibility of its Contribution to the Sensory Quality of Fermented Foods. Fermentol Techno 4:121.

Copyright: © 2015 Kuroda M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.