SACCHAROMYCES UVARUM, SACCHAROMYCES EUBAYANUS AND ARTIFICIAL HYBRIDS FOR LOW TEMPERATURE CIDERMAKING

GONZÁLEZ M.; RODRÍGUEZ M.E.; ORIGONE A.; OTEIZA J.M.; LOPES C.A.

Recife

Jornada; V Jornadas Sudamericanas de Biología y Biotecnología de Levaduras; 2015

Saccharomyces uvarum (Su) and Saccharomyces eubayanus (Se) are cryotolerant yeasts that produce higher glycerol and lower ethanol concentrations than Saccharomyces cerevisiae (Sc), as well as particular aromatic profiles. However, most strains of these species are not able to complete alcoholic fermentation of sugar rich musts. Artificial hybrids obtained from these cryotolerant species and Sc could group in a single strain, the most relevant features of each parental species. The aim of this study was to evaluate the potential of North Patagonian selected strains belonging to Su and Se species to produce ciders at low temperature, as well as to generate artificial hybrids with Sc with improved fermentative performance. Hybrids were obtained by rare-mating and confirmed by PCR-RFLP. Genetic stabilization of hybrids was carried out by sequential fermentations in apple must at 13ºC and evaluated by specific molecular markers. One stable hybrid from each cross, as well as their respective parental strains were used to perform fermentations of Granny Smith Apple must (1L) at 13ºC. Fermentation kinetics were monitored by measure of ºBrix, glucose and fructose concentrations and curves were fitted using sigmoidal or exponential equations. Both cryotolerant parents and hybrids consumed more sugars than Sc, although hybrids showed the highest fructose consumption rate (0.043±0.001b vs 0.012±0.001a gh-1) and cryotolerant parents showed the highest glucose consumption rate (0.017±0.002b vs 0.008±0.002a gh-1). Analysis of main chemical parameters evidenced that Se produced the highest glycerol concentrations (5.08±0.24b vs 4.07±0.08a gL-1). The aromatic profile of ciders, analysed by gas chromatography, evidenced that Se and Su produced higher concentrations of higher alcohols than the rest (211.0±3.6a vs 135.4±6.1b mgL-1) especially isoamyl alcohol (180.35±4.29b vs 89.6±27.3a mgL-1) and 2-phenylethanol (13.37±3.31b vs 4.78±1.21a mgL-1). Su produced higher total esters concentration than the other strains (29.01±4.32b vs 7.97±2.04a) especially ethyl acetate (28.42±1.86b vs 7.61±1.99a), and both Su and the hybrids synthetized the highest amounts of ethyl hexanoate (0.17±0.005b vs 0.059±0.001a mgL-1), chemical compound associated with green apple aroma, even higher than its respective perception threshold. Both the hybrids and the cryotolerant parental strains evaluated in this work evidenced better fermentative and aromatic features than Sc for low temperature cidermaking.