The Mechanism Of Wine Polysaccharides On Wine Astringency By Interfering With Proanthocyanidin-protein Interaction

High-quality red wine has a pleasant complex taste,while astringency is an important feature of red wine quality.Proanthocyanidins(i.e.condensed tannins)are the main contributors to wine astringency,which determine the aroma and color of red wine,as well as one of the important functional components in wine.Polysaccharides,another important macromolecular substance in wine,not only regulate the astringency of wine and improve color stability,but also increase the stability of protein and tartar.At present,the specific relationship between wine astringency of polysaccharides molecular weight size,monosaccharide composition and other characteristics is not clear,and the specific mechanism of polysaccharides regulating wine astringency needs to be further discussed.This experiment intends to use the polysaccharide and proanthocyanidins from saccharomyces cerevisiae,cabernet sauvignon and cabernet sauvignon red wine as research object.The contents and structures of polysaccharides and proanthocyanidins were identified and analyzed by High performance liquid chromatography(HPLC),high performance volume exclusion chromatography(HPSEC),and ultraviolet-visible spectrophotometer(UV-Vis).The influence of polysaccharides with different types on the interaction of proanthocyanidins-bovine serum albumin(BSA)were explored by the laser particle analyzer,sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE),and fluorescence spectrometry in model wine,in order to establish the relationship between the astringency of wine and the differences of polysaccharides and the characteristics of proanthocyanidins.The research results can provide theoretical basis and guidance for improving and optimizing the astringency of red wine,providing a reference for selecting appropriate wine grape cultivation techniques and evaluating the sensory quality of wine.The results are as follows:1.The polysaccharides were graded by ethanol at different concentrations to obtain PS-40(3.68×105),PS-50(1.86×105),PS-60(1.79×105),PS-70(4.92×104)and PS-80(1.5×104).The sum particle size distribution was 312.54nm(PS-40)-92.69nm(PS-80).Monosaccharide composition analysis of polysaccharide samples were that the contents of mannose,galactose and arabinose of polysaccharide samples with large molecular weight were high,while the contents of rhamnose from polysaccharide samples with small molecular weight were significantly increased.The mean degree of polymerization,percentage of epicatechin and percentage of acylation degree of proanthocyanidins separated from the three wines were PA1>PA2>PA3,PA1>PA2>PA3 and PA3>PA2>PA1,respectively.When the PS-80 with the minimum molecular weight was added to the proanthocyanidins simulation liquor,the binding of protein and proanthocyanidins was obviously promoted,and the resulting protein precipitation was reduced.However,the binding reaction between protein and procyanidins was weakened to some extent when PS-50 with larger molecular weight was added to the simulated liquor,but the production of protein precipitation was also reduced.The results showed that the polysaccharides with large and small molecular weights reduced the deposition of proteins by different reaction pathways.Secondly,the structural difference of procyanidins has a great influence on the reaction of the three.The reaction intensity and degree of change with polysaccharides and proteins were shown as PA1>PA2>PA3.2.The molecular weight of each polysaccharide extracted from different raw materials was 1.85×103(JPS),4.46×104(SPS),2.35×105(WPS)and 7.92×105(YPS),respectively,and the particle size distribution was 116.51nm(JPS)-297.52nm(YPS).Mannose content was the highest in yeast polysaccharides,monosaccharides were detected in wines,and mannose,rhamnose,glucuronic acid,arabinose and galactose contents were higher than others.Glucuronic acid and galactose contents were the highest in SPS and JPS，respectively.But there is no mannose in either.When high molecular weight YPS was added to the simulated liquor,the interaction between protein and procyanidins was significantly reduced.However,the interaction between SPS and proanthocyanidins-protein was significantly enhanced when SPS with lower molecular weight was added to the model wine.Compared with the control group without added polysaccharides,adding polysaccharides greatly reduced the protein precipitation.These have indicated that YPS and SPS have different mechanisms for regulating procyanidin-protein interactions.3.The molecular weights of the three polysaccharides were 5.77×105(MPs),4.05×104(AGPs)and 2.66×103(RG),and the particle size distribution was 352.59nm(MPs)-119.06nm(RG).MPs,AGPs and RG contained the most mannose,arabinose and galactose and rhamnose,respectively.When polysaccharides were added to the simulated liquor,the RG with small molecular weight and its mixed polysaccharides combined with AGPs significantly promoted the binding of the three substances.MPs with higher molecular weight inhibited the reaction between the protein and procyanidins.After the addition of polysaccharides,low protein deposition capacity was shown in all samples.To our knowledge,based on the existing research on the mechanism of polysaccharides regulating wine astringency,the contribution of different polysaccharides and proanthocyanidins to wine astringency was further explored.The purpose is to provide data support and guidance for the mechanism of polysaccharides improving wine astringency and its application in practical production.