Physiological and molecular characterization of yeasts present during spontaneous cider fermentations

BARBAGELATA R; LOPES C; VAN BROOCK MR; CABALLERO A; SANGORRÍN M

San Carlos de Bariloche

Congreso; XXXIX Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2003

The transformation of must apple into cider by spontaneous alcoholic fermentations is the result of the sequential development and metabolic activity of various species of yeasts originated from apple and cidery surfaces. The aim of this work was to isolate, to characterize and to compare yeast microbiota from fermenting apple musts in two cideries. Initial musts from both cideries, were also fermented in laboratory. The samples were took at three stages of spontaneous alcoholic fermentation: initial, middle and end. Yeast characterization at species and strain level was performed according to conventional physiological, morphological and molecular methods (RFLP of the ITS1-5.8S-ITS2 and mtDNA-RFLP). Differential killer sensitivity was also used as a tool for fingerprinting at strain level. Pichia membranaefasciens, Pichia kluyveri, Dekkera anomala, Torulaspa delbrueckii and Kloeckera apiculata were identified in the initial stages of fermentation from both cideries. Saccharomyces cerevisiae turned out the most among those isolated at middle and final stages. The killer phenotype (K+) was observed in 80% of cider yeasts. The dominant strains in both industrial and laboratory vinification processes were just a few and the same. The quality of the final products was very similar, with the exception of the volatile acidity. We can conclude that there exist a great diversity of wild yeast in the cideries with particular roles in the fermentation processes.