Storage of Immobilized Yeast Cells for Use in Wine-Making at Ambient Temperature

Abstract
A comparative study of the storage and reuse of immobilized yeast cells on apple pieces, kissiris, and γ-alumina was carried out. The immobilized biocatalysts were allowed to remain in the fermented alcoholic liquid after the end of each fermentation batch for extended periods at 30 °C before reactivation in batch fermentation for wine-making. The results showed that the biocatalysts were able to reactivate and ferment after successively increased periods of storage compared to free cell systems both on glucose medium and on grape must. In glucose medium, apple-, kissiris-, and γ-alumina-supported biocatalysts reactivated after 120, 80, and 83 days, respectively. Possible storage periods for grape must were lower but remained high. Immobilized yeast biocatalyst on apple pieces produced wines with an improved volatiles composition compared to kissiris- and γ-alumina-supported biocatalysts. There were no significant negative effects on the fermentation activity and volatile byproduct composition. Keywords: Preservation; immobilized cells; wine-making; yeast biocatalyst