Wine fining with yeast protein extract: effect on polyphenol composition and the related sensorial attributes

Polyphenols, namely anthocyanins and flavanols, are key compounds for wine color definition and taste perception (astringency and bitterness). During winemaking, several processes could influence the polyphenol composition and, therefore, the organoleptic parameters of wine. 

It is widely known that fining can remove soluble substances, including polymerized tannins and coloring matter in red wines affecting the organoleptic properties of wine. The use of yeast protein extracts (YPE) as fining agents arises from the allergic properties observed in classic protein-based fining agents. From the oenological point of view, it was already verified that this new fining agents promote the clarity and stabilization of wine, however is still a gap in their influence in polyphenol composition and the related organoleptic properties. 

The aim of this work is to understand the molecular mechanisms as how YPE-wine polyphenols interactions could modulate the color as well as the taste sensations (astringency and bitterness) after wine fining with YPE (developed by Proenol, Biotechnology Industry). Briefly, polyphenols related with astringency and bitterness were analyzed by LC-MS. The influence of YPE on wine color was also assayed by CieLab system. Furthermore, the effect of YPE-wine on the interaction with salivary proteins was also analyzed by SDS-PAGE after wine ingestion during a sensory evaluation. Finally, the results from experimental data were compared with the results obtained by sensorial panel. 

Overall, it was concluded that wines clarified with YPE revealed a significant decrease in the majority of identified compounds related to bitterness and astringency. The study of wine color revealed that YPE had the ability to reduce yellow color of white wines and did not remove red color of red and rosé wines, which is an important aspect in consumption market. Besides the decreasing of several polyphenols related with taste perception, some relevant differences were observed in the salivary protein profile by SDS-PAGE. The results observed herein highlighted the relationship between (1) the taste perception, (2) the interaction between salivary proteins and wine polyphenols during the sensorial evaluation and (3) the effect of YPE fining in wine polyphenols. 

In summary, YPE reveals to be a good alternative to protein animal origin fining agents due to the ability to promote wine sensorial properties.

Authors: Telmo Francisco, Rosa Pérez, Susana Soares, Nuno Mateus, Victor Freitas, Adriana Xavier, Manuel Figueiredo, Filipe Centeno, Maria Teixeira 

LAQV-REQUINTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto 
PROENOL, Indústria Biotecnológica, Lda, Travessa das Lages nº267, Apto 547, Canelas, VNG 4405-194 Portugal


Keywords: fining, yeast protein extract, organoleptic properties, salivary proteins 

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