The final concentration of phenolic compounds in wines is usually lower than what might be expected, given their concentration in grapes. This is in part due to the interactions between cell walls from grapes and yeast with phenolics during red winemaking. Most of these aggregates are insoluble and end up precipitating, forming part of the lees. The objective of this study is to determine the capacity of ultrasounds and/or enzymes treatments (β-glucanase and a pectolytic enzyme) to release the anthocyanins and tannins adsorbed in the lees. The ultrasound (US) applied for 120 min slightly favored the extraction of anthocyanins and doubled tannin extraction. Shorter sonication times did not show any positive effect. The combination of β-glucanase and pectolytic enzyme was always more effective in the liberation of anthocyanins (both no-acylated and acylated anthocyanins) and tannins than the enzymes acting separately. The combination of US (120 min), β-glucanase and pectolytic enzyme showed an additive effect, increasing the extraction of phenolic compounds with respect to the individual treatments and also releasing a large quantity of low molecular weight polysaccharides, compounds of enological importance. These results of this study could be of enological interest, facilitating and accelerating the aging on lees process, through the liberation of polysaccharides and the recovery of the phenolic compounds lost during vinification.
Keywords: anthocyanins; lees; pectinase; tannins; ultrasound; β-glucanase.