Efecto de la aireación en la producción de compuestos volátiles por cultivo mixto de Brettanomyces intermedius y Saccharomyces cerevisiae durante la fermentación de sidra

The influence of aeration on the fermentative activity of Brettanomyces intermedius RIVE 2-2-2 was studied in a mixed culture with Saccharomyces cerevisiae RIVE 15-1-416 in order to evaluate the production of chemical compounds of sensory importance. To achieve this, the strains were cultured in Erlenmeyer flasks containing sterilized and aroma-removed apple juice. The chemical compounds produced during fermentation under shaking (200 min⁻¹) or static cultivation were determined by gas and liquid chromatography. The results showed that the stirring during cultivation diminishes the production of glycerol (0.53±0.1 g/L) and acetic acid (94.0±10.0 mg/L) and, on the other hand, increases the production of higher alcohols (1.009 g/L) and ethyl acetate (122.0±5.0 mg/L). Additional batch cultivations carried out in a bioreactor with an air flow of 25 l/h reported a growth rate (μ) and a biomass yield (Y_x/s) of 0.05 h⁻¹ and 0.24 (g. dry biomass/g. sugar) respectively. At the end of cultivation, no presence of acetic acid was observed and furthermore, concentrations of ethanol and glycerol reached values of 0.34±0.1 g/L and 1.3±0.05 g/L respectively. The best results in terms of organoleptic quality of the cider regarding to taste and smell were obtained when fermented under static cultivation conditions. The regulation of aeration during fermentation is a useful tool to control the fermentative activity of these two strains in a mixed culture.