Different approaches to supplement polysaccharide-degrading enzymes in vinification: effects on color extraction, phenolic composition, antioxidant activity and sensory profiles of Malbec wines

Abstract

Enzymes play an essential role in the winemaking process. Besides an improvement in the color of the wine it also enhances the quality, which makes it well worth to develop new strategies of application. The present study examined two approaches to apply microbial enzymes during different winemaking techniques using Malbec grapes from the San Rafael wine region, Mendoza, Argentina. i) Torulaspora delbrueckii was used in sequential inoculation with an autochthonous Saccharomyces cerevisiae strain. The former strain was first inoculated to produce in situ an enzyme complex during winemaking for four days, and subsequently the latter strain was added. The process was carried out under traditional winemaking conditions at 22 °C (Td-Sc). ii) A second approach was through inoculation of a multi-enzyme extract produced by Aureobasidium pullulans m11-2 during pre-fermentative cold maceration (PCM) for four days at 8 °C (PCM-E), and S. cerevisiae was inoculated at the end of the PCM. Controls were carried out without enzymatic treatments (Sc and PMC, respectively). T. delbrueckii started the fermentation and remained viable throughout the process. The fermentation kinetics were not affected in the mixed culture compared with a pure culture of S. cerevisiae. Monitoring of the pectinolytic activity of Td-Sc showed maximum activity (14.2 U mg−1) on day one of the inoculation, while in PCM-E the must activity increased during the PCM until day one of fermentation, reaching a maximum of 16.85 U mg−1. Both enzyme-treated wines maintained their red hue, regardless of the duration of the macerations, while the control wines were characterized by a faster rate of color loss and more yellow tones. In the sensory evaluation, enzymatically treated wines presented greater color intensity, redder and more violet tones, floral and fruit aromas, which are also the distinctive features of the Malbec variety. Anthocyanin values obtained in PCM and in PCM-E were higher than in vinifications without cold maceration (Td-Sc and Sc), which could be attributed to the effectiveness of the maceration technique. Similarly, the composition of stilbenes, especially trans-resveratrol, showed an increase in PCM techniques with or without enzymatic treatment, and both techniques were comparable to one other and statistically superior to traditional winemaking.