Autochthonous Metschnikowia sp. as a biological tool for protein stabilization and aroma enhancement in wine

Abstract

The use of non-Saccharomyces yeasts is gaining increasing interest as a strategy to enhance wine quality while reducing the need for technological additives. Several non-Saccharomyces species exhibit enzymatic activities that may be exploited during vinification, provided that they are accurately selected at strain level.

In this study, an autochthonous Metschnikowia sp. strain isolated from grape berry surfaces in the Collio DOC area (Friuli Venezia Giulia, Italy) was investigated for its proteolytic and β-glucosidase activities. The strain was selected following a preliminary screening of yeasts isolated from local vineyards.

Proteolytic activity was clearly detected in vitro and subsequently confirmed under oenological conditions. The strain was able to degrade wine proteins, generating degradation patterns comparable to those obtained with a commercial proteolytic enzyme, suggesting a potential application in the management of protein instability.

β-Glucosidase activity was initially assessed through plate assays and subsequently evaluated during microvinification trials carried out on aromatic grape must. Mixed and sequential inoculations with Saccharomyces cerevisiae were performed. The volatile profile was analysed by SPME–GC–MS in order to detect variations in aroma-related compounds potentially associated with the release of glycosylated precursors.

Overall, these findings highlight the potential of this autochthonous Metschnikowia strain as a multifunctional biological tool combining proteolytic and β-glucosidase activities. Its use may represent a practical strategy to support both aroma expression and protein stability, contributing to more sustainable winemaking practices based on the valorisation of local microbial resources.