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Influence of pectolytic enzymes on the level of flavonoid and nonflavonoid polyphenols in red wine

The purpose of this work is to evaluate the impact of pectolytic enzymes and duration of maceration on the rate of extraction and yield of flavonoid and nonflavonoid polyphenols in red wine produced from pure red grape variety Crljenak (Primitivo, Zinfandel). A traditional maceration with (RWE) and without (RW) pectolytic enzymes was performed. Changes in phenolic composition were monitored during fermentation and until the second racking. Total phenols were determined by Folin Ciocalteu method, and absorbance at 520 nm was taken as indicator of anthocyanins content. The presence of individual polyphenols was analyzed by HPLC-RP-PAD technique. As expected, a continuous increase in the levels of total phenols, flavonoids and anthocyanins was noticed during the monitoring period of wine fermentation. According to the obtained results, addition of pectolytic enzymes to must, prior to fermentation, significantly influenced the extraction rate of catechin monomers (+)-catechin and (-)-epicatechin (CM), procyanidin dimers B1 and B2 (PC), cis- and trans-resveratrol monomers (RM), and major resveratrol derivative piceid (P). During the first days of maceration the extraction rate of polyphenols in RWE was more than twofold higher in comparison to RW. The concentrations of individual polyphenols, after the third day of maceration, were 69.6, 53.8, 7.5 and 1.9 mg/L of RWE and 31.5, 20.7, 1.9 and 0.2 mg/L of RW, successively given for PC, CM, RM and P. In spite of more intensive extraction of polyphenols in RW until the end of maceration, higher amounts of polyphenols, either flavonoids or stilbenes, were found in young RWE wine. The slow but continuous decrease of piceid concentrations during postfermentative period was noticed. Red wine stability in relation to stilbene polyphenols still remains a challenge for the future.

red wine; pectolityc enzymes; flavonoids; stilbenes

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