Application of a grape surface majority pectinolytic species, Aureobasidium pullulans, to low-temperature red winemaking: development and stability of wine colour

ABSTRACT Low-temperature red winemaking is mainly used for enhancing the wine aroma; however, colour and phenolic extraction is reduced under this condition. This work evaluated the effects of the pectinolytic strain Aureobasidium pullulans GM-R-22, belonging to the most abundant species in grape surface and the greatest pectinase producer, applied to pre-fermentative cold maceration and low-temperature fermentation, on anthocyanin extraction, chromatic and technological properties, also on sensory attributes of Malbec wines. A. pullulans demonstrated to survive in grape juice and first days of fermentation, and high levels of pectinase activity were detected in GM-R-22 vinifications. GM-R-22 wines exhibited higher total anthocyanins, total polyphenolic index and colour intensity (CI), as well as filtration times 30% lower. GM-R-22 wines showed an increase in monomeric anthocyanins during fermentation and higher polymeric pigments at 9 months of bottle storage, suggesting a greater stability in wine colour. From a sensory standpoint, GM-R-22 wines obtained higher scores for CI and violet hue than their respective controls, improving aroma and equilibrium. This study proved that it is feasible to use this unconventional microorganism in oenology to produce pectinases during the low-temperature winemaking process to attain wines with similar or better chromatic properties to those of traditional wines.