Oxidative Polymerization Of The Phenolic Compounds In Ciders

It had a major effect to its sensory character,colour,odour and end product's quality of the oxidative polymerization of the phenols in ciders.In this paper,treated six kinds of apple varieties and ciders as the objects of study,a method of detecting twelve single phenols was established.Using this means,it may be measured about those contents.Through analyzing the characteristic of these phenols,it was found that catechin,epicatechin,chlorogenic acid and caffeic acid were the most single phenols in apples and in ciders whose contents were rich.Under the condition of enzymatic oxidation,it was studied by the experiment of oxidative polymerization of catechin,epicatechin,chlorogenic acid and caffeic acid in the cider model system.It was found that the polymerization of chlorogenic acid and caffeic acid had a greater degree increase by time,especially that chlorogenic acid,which polymerization had three-fold increases.Their degree of astringency(RA) were also constant to increase with the polymerization.But that catechin and epicatechin only had a small increase in the polymerization and RA.It was proved that chlorogenic acid and caffeic acid were the main substrates in the process of enzymatic oxidation which ran the reaction of polymerization.Under the condition of non-enzymatic oxidation,the speed of the polymerization of these four phenols was relatively slow.The polymerization of catechin and epicatechin had a continued increase by time,especially that catechin which polymerization had four-fold increases.And so were those RA.But the polymerization and RA of chlorogenic acid and caffeic acid basically had no changes.It was proved that catechin and epicatechin had a leading role during the final fermentation and storage of ciders in the process of non-enzymatic oxidation.These were analysed about the products of oxidative polymerization of catechin and chlorogenic acid by LC-ESI/MS.Results indicated that in the process of enzymatic oxidation there was a small amount of dimer of catechin in its products.It was proved that catechin generated a light polymerization reaction in this course.But chlorogenic acid totally was oxidized to p-quinone,which was considered that p-quinone initiated the reaction of polymerization.Relative to non-enzymatic oxidation,there was dimer of catechin,even trimer in its products,whose contents were more than in the condition of enzymatic oxidation.And in the products of chlorogenic acid,there was a smaller products of p-quinone.These results further testified that there were great differences of the substrates,products and the course of reaction in the enzymatic oxidation and non-enzymatic oxidation.