Effect Of Grape Polysaccharides On The VolatileComposition Of Red Wines

Resumen

Yeast mannoproteins and derivates are polysaccharides produced from the cell walls of different yeast strains widely used in the winemaking and finning of wines to improve their overall stability and sensory properties. Some studies reported that mannoproteins maintain the wine aroma tending to be more appealing. On the contrary, grape polysaccharides are not commercially available, and the recovery of these compounds from grape by-products is nowadays a great challenge for the oenological research. These polysaccharides have a great potential in organoleptic finning since they have been reported to modulate the wine quality, as arabinogalactans which interacts with wine aroma compounds and increase their volatility (Ribeiro et al., 2014; Rinaldi et al., 2021).In this study grape polysaccharide extracts obtained from different sources were used as finning agents at bottling in three wines from Vitis vinifera L. cv. Tempranillo and Graciano. Their effect on the volatile composition and profile was analyzed. Polysaccharides extracts were obtained from white pomace by-products (WP), red pomace by-products (RP), white must (WM), red must (RM), red wine (RW), and lees recovered after the winemaking (RL). Two more extracts with higher purification degrees were used (PE1 and PE2). The results were compared with a control (C) wine sample and with mannoproteins commercially available (CM).The analysis of volatile compounds was performed using a GC-MS after a liquid-liquid extraction as described by Oliveira et al., 2006. Discriminant analyses were performed to differentiate the red wines by the fining extract used. WM, RM and CM wines were characterized by high contents of alcohols, C6 alcohols, some esters as ethyl isovalerate, acetates, acids, and terpenes. On the other hand, RW, RP, and RL wines were characterized by high contents of ethyl esters as ethyl lactate, ethyl hexanoate and ethyl octanoate, and volatile phenols, specially 4-vinylguaiacol and 4-ethylguaiacol. The wines treated with PE1 and PE2 were those which presented the lowest concentrations on most of the volatile compounds detected. Discriminant analyses showed that the use of the polysaccharide extracts modified the volatile composition of the wines.