Low‐temperature wine‐making using yeast immobilized on pear pieces

Abstract

A biocatalyst was prepared by the immobilization of Saccharomyces cerevisiae AXAZ-1 yeast cells on pear pieces and tested for grape must fermentation in both batch and continuous conditions. The immobilized yeast cells were stable and active even at low temperatures (<10 • C). Wine production under batch fermentation at 8 • C was completed within 15 days while at 3 • C it took 36 days. In continuous fermentation, the bioreactor was operated for 33 days, then stored for 12 days at 10 • C, and re-run for another 15 days without any diminution of the ethanol productivity. Total acidity of the produced wines remained within the ranges usually observed in dry wines, while volatile acidity was found in rather increased levels. The concentrations of higher alcohols (1-propanol, isobutyl alcohol and amyl alcohols) were relatively low, while ethyl acetate was detected at up to 118 mg l −1 , contributing to the fruity aroma of the wines produced. Preliminary sensory evaluations carried out in the laboratory indicated the fine quality of the produced wines.

Effect of fermentation conditions and immobilization supports on the wine making

“…Cell immobilization on apple (Kourkoutas et al, 2001), quince (Kourkoutas et al, 2003) and pear (Mallios et al, 2004) pieces was carried out as described earlier. In brief, pieces of apple, quince and pear were introduced separately in synthetic medium consisting of glucose and the appropriate amount of biomass and was allowed to ferment.…”

“…Apple (Kourkoutas, Komaitis, Koutinas, & Kanellaki, 2001; quince Kourkoutas et al, 2003) and pear (Mallios et al, 2004) pieces have been already used successfully for immobilization of Saccharomyces cerevisiae yeast in both batch and continuous wine making and the final product had improved quality. In addition, they are cheap, of food grade purity, abundant in nature and would possibly lead to a product with improved taste and aroma due to potential transfer of some of their constituents into the wine.…”

Wine produced by immobilized cells on dried raisin berries in sensory evaluation comparison with commercial products

“…Similar results showing improved quality in wines produced by immobilized cells compared with wines produced by free cells have been reported previously. 7,16 However, both wines were accepted by the panel, although they were low in the tasters' preference. This was despite the fact that the must used for wine production in the laboratory was of inferior quality and that no post-fermentation treatments were carried out that are primarily aimed at the removal of yeast which detract from the desirable aromas, thus leading to possible reduced aroma intensity.…”

Study of the growth rate of Saccharomyces cerevisiae strains using wheat starch granules as support for yeast immobilization monitoring by sedimentation/steric field-flow fractionation

“…Improvements in maximum growth rate and productivity in biomass production using orange peel as promoter were observed in batch aerobic fermentation (Plessas, Kourkoutas, Psiarianos, Kanellaki, & Koutinas, 2006). Shorter time and temperature fermentation processes with lower byproducts production were also achieved (Mallios et al, 2004;Plessas, Bekatorou, Kanellaki, Psarianos, & Koutinas, 2005).…”