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Isolation of indigenous yeasts from unripened grapes not subjected to antifungal treatments
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1  Universitat de València


The wine fermentation process is very complex and involves different types of yeasts. While the predominant one is Saccharomyces cerevisiae, it has long been known that other non- Saccharomyces yeasts also play an important role. Their action is mainly known in the early stages of fermentation. However, one should not overlook the processes and changes that non-Saccharomyces yeast populations may have undergone during previous stages of grape berry ripening. The whole process is conditioned by several environmental factors as well as the possibility that they have been subjected to some antifungal treatment. In our study we controlled the dynamics of non- Saccharomyces yeast populations during the ripening process, using biochemical identification systems (API 20C AUX and API ID 32C) as well as molecular techniques (RFLP-PCR) and enzymatic analysis. Some yeasts not usually found in wine fermentation (Aureobasidium pullulans, Cryptococcus sp., Metschnikowia pulcherrima and Rodotorula mucilaginosa) have been identified. These yeasts could be affected by antifungal treatments used in wineries, and this fact could explain the novelty of their isolation and identification. After their extensive characterization, these yeasts can be used to implement new biotechnological processes.

Keywords: yeast; non-Saccharomyces; grape berry; population dynamics; ripening; wine