Effect of pectinase - surfactin system on pigments and total polyphenols extraction from Malbec grape skins

Abstract

The effects of a surfactin from Bacillus subtilis C4 on the extraction of anthocyanins, other pigments, and total polyphenols by action of a pectinase from Bacillus sp. SC-H during a short maceration of Malbec grape skins were studied. A prefermentative extraction from skins free of pulp and seeds with an extraction solution in absence of ethanol for 2 hours was carried out. Color was measured by tristimulus colorimetry and traditional indices (color index, shade, and total polyphenol content) and anthocyanins were determined by HPLC. The color index increased from 2.878 ± 0.281 for natural extraction, to 5.500 ± 0.107 for samples with pectinase plus 0.095% surfactin, and to 6.036 ± 1.013 for samples with pectinase plus 0.286% surfactin. Total polyphenol content increased from 555.77 ± 5.00 mg GAE/L for natural extraction to 769.71 ± 38.21 mg GAE/L and to 769.05 ± 8.40 mg GAE/L for the aforementioned samples. Anthocyanic compounds were readily released from grape skins, especially malvidin derivatives, which are the main pigments responsible for red wine color. Malvidin-3-glucoside was increased by 10% and 15% and malvidin-3-acetylglucoside by 21% and 29% with the enzymatic and enzyme-surfactin treatments, respectively. The coordinates and CIELAB color differences were improved with respect to natural extraction because of red pigments; thus, the macerates became darker and with a more vivid color, with the best values corresponding to the highest surfactin concentration studied. The simultaneous use of the enzyme and surfactin enhanced the indices and anthocyanin composition during a short extraction from grape skins. However, it is necessary to study the effects on entire berries and in real winemaking conditions. Further investigation is required in order to propose red wine maceration with the addition of pectinasesurfactin complex as a new tool in winemaking.