Effect of SO_2 Concentration on Polyphenol Development during Red Wine Micro-oxygenation

摘要

A Merlot wine in 15 L research tanks was subjected to micro-oxygenation at 10 mL O_2 per liter of wine per month over a 16 week period with additions of 0, 50, 100, and 200 mg/L SO_2. A large decrease in monomeric anthocyanins and flavan-3-ols was seen in wines with a lower concentration of SO_2, coupled with an increase in nonbleachable pigments; an increase in tannin, measured using precipitation with methyl cellulose; and a greater size and red coloration of a proanthocyanidin extract obtained using Sephadex LH-20. These changes were largely suppressed in wines initially treated with 200 mg/L SO_2 and occurred more slowly in wines stored in bottles in the absence of O_2. The concentration of SO_2 is shown to regulate the polyphenol chemistry involved in the formation of polymeric pigments and changes in tannin structure affecting wine astringency.