Investigating kokumi flavour oligopeptides in wine

Abstract

Kokumi is a complex sensation perceived as enhanced palatability. Under the influence of kokumi substances, foods/beverages tastes become more flavorful with increased intensity, spread, continuity, richness, harmony, and punch which are the six related characteristics corresponding to the Kokumi sensory concept [1]. Kokumi active peptides are distributed in many foodstuffs and relevant in fermented ones due to yeasts derived oligopeptides. Kokumi peptides identified from yeast extract showed diverse sensory features tested by sensomic approach: five leucyl dipeptides, γ-glutamyl dipeptides and the well-known kokumi-active glutathione (GSH) a tripeptide (γ-Glu-Cys-Gly) also present in grape and wine [2] [3].

Wine likely is the fermented beverage for which the sensory features represent one of the main quality characteristic driving appreciation and purchase. Sparkling wines produced through the Champenoise method, undergo a second fermentation in the bottle prior to aging in contact with yeast lees. Based on current knowledge, these production conditions make it possible to speculate on the potential presence of kokumi oligopeptides in wine, an issue that has not been explored. It has been stated that “koku” for wine is customarily expressed as “body” [4] but no evidence is reported and the kokumi sensory dimension in wine is currently unknown.

This gap of knowledge has been addressed in a series of metabolomic, molecular docking and sensory analysis experiments. The kokumi sensory activity of Glycyl-L-Valine (Gly-Val) was shown. This dipeptide has been identified in 34 sparkling wines, within a pool of 11 oligopeptides able to interact (in-silico molecular docking) with the Calcium Sensing Receptor (CaSR), the protein necessary to activate kokumi sensations [5]. Trained panellists (32) evaluated the impact of Gly-Val in model wine (MW: 12% v/v EtOH, 6.30 TA, 3.0 pH)), white wine (WW), and sparkling base wine (SBW) using triangle tests (T), three alternative forced choice test (3-AFC) and descriptive analysis with relative reference scaling (DA with RR scaling). In T the odd sample with Gly-Val was correctly identified only at the highest concentration (120 mg/L) in MW, while at lower concentrations in WW (15-60 mg/L) and SBW (30-90 mg/L). Detection thresholds of Gly-Val, estimated by 3-AFC, ranged from 15 to 60 mg/L in wine, while no threshold was determined in MW. These results show that Gly-Val is discernible in complex wine matrices but not in a simplified matrix such as the model wine. This suggests for the first time that Gly-Val is a kokumi active compound, indeed a kokumi compound is intended as a molecule able to modulate in-mouth sensations in complex matrices [1]. Based on these results, further 6 dipeptides are currently being studied to test their potential kokumi flavor in wine, according to the detected compositional patterns.

References

[1] Yamamoto, T., Inui-Yamamoto, C. (2023). npj Sci Food 7, 3

[2] Liu, J., Song, H., Liu, Y., Li, P., Yao, J. and Xiong, J. (2015) J. Sci. Food Agric., 95: 3183-3194

[3] Ueda, Kuroda, M. (1997). Kokumi Substance as an Enhancer of Koku Biochemistry, Physiology, and Food Science. Eds.; SpringerNature, Singapore

[4] Nishimura, T.; Kuroda, M., (2019) In Koku in Food Science and Physiology: Recent Research on a KeyConcept in Palatability. Eds.; SpringerNature Singapore

[5] Perenzoni, D., Dellafiora L., Perugino, F., Vrhovsek, U., Piombino, P., Pittari, E., Guzzon, R., Moio, L., Galaverna, G., Mattivi, F. (2024). J. Agric. Food Chem. 72 (47), 26189-26208.