ENHANCED GLYCEROL CONTENT IN WINES MADE WITH IMMOBILIZED CANDIDA-STELLATA CELLS

Screening tests carried out for 10 strains of Candida stellata confirm ed high levels of glycerol production, although a low fermentation rat e and reduced ethanol content were observed, To overcome the poor comp etition with Saccharomyces cerevisiae, fermentation tests with immobil ized C. stellata cells! alone or in combination with S. cerevisiae, ha ve been carried out, The immobilization of C, stellata cells consisten tly reduced the fermentation length when compared with that obtained w ith free cells, immobilized cells exhibiting about a 30- and a 2-fold improvement in fermentation rate compared with rates for C. stellata a nd S, cerevisiae free cells, respectively. Moreover, immobilized C. st ellata cells produced a twofold increase in ethanol content and a stro ng reduction in acetaldehyde and acetoin production in comparison with levels for free cells. The evaluation of different combinations of C. stellata immobilized cells and S. cerevisiae showed interesting resul ts with regard to analytical profiles for practical application in win e making. In fact, analytical profiles of combinations showed, apart f rom a high glycerol content, a reduction in the amounts of acetic acid and higher alcohols and a consistent increase in succinic acid conten t in comparison with values for the S, cerevisiae control strain, Sequ ential fermentation first with immobilized C, stellata cells and then after 3 days with an added inoculum of S. cerevisiae free cells was th e;best combination, producing 15.10 g of glycerol per liter, i.e., 136 % more than the S. cerevisiae control strain produced. Fermentation wi th immobilized C. stellata cells could he an interesting process by wh ich to enhance glycerol content in wine.