Changes Types And Affecting Factors Of Non-enzymatic Browning In The Process Of Musalais

In this study,samples of the Mussalas brewing process from Xinjiang Awadi Musallas Co.,Ltd.were collected and analyzed for L^*,a^*,b^*,non-enzymatic browning(A_420nm),and Maillard reaction intermediate(A_294nm),Browning Index?BI?,Chromaticity?C^*?,Hue Angle?H°?,Whiteness Index?WI?and Yellowness Index?YI?,and their correlations and the kinetics with total Sugar,Total Phenols,Amino Acidsand Ascorbic Acid?Vc?.It were analyzed for the main non-enzymatic brown discoloration index and their changes during the process of Musalais.The different models with different chemical compounds were used to determine which types non-enzymatic browning type present and their important contributing substrates in the simulated process of Msalais.And the results were verified by laboratory micro-brewing of Msalais.The effecting factors on non-enzymatic browning in the process of Msalais were investigated in the laboratory.The result is as follows:?1?During the process of Msalais,the correlations between the color index and total sugar,and total phenols shown zero-order or first-order kinetic models.During the concentration of grape juice,BI and YI shown a first-order kinetic relationship with total sugar,and highly correlation with A_420nm?R:0.624 and0.647 respectively?.Thus,BI,YI and A_420nm20nm were determined as an important non-enzymatic brown discoloration index in the process of Msalais.The color changes during the concentration of grape juice shown the increasing ofa^*,b^*,YI,and the decreasing of BI,C^*,L^*,WI,H°,namely,the color was changed from green to red brown;During the fermentation process ofconcentrated grape juice,a^*,C^*,BI,YI decreased,H°,L^*,WI increased,and b^*remained roughly even level,the color of fermenting juice changed from reddish-brown to yellow-brown.In the process of Msalais,the non-enzymatic browning was significantly accelerated in the concentration of grape juice,but rapidly decreased in the early stage fermentation,and slowly and limitly increased again in the late stage of fermentation and the ripening period of Msalais.?2?Non-enzymatic browning reaction main occured in the grape juice concentration.The main type was Maillard reaction,followed by caramelization reaction,oxidation condensation reaction of polyphenols and degradation of ascorbic acid.At this stage,the important contributing substrates to non-enzymatic browning were:glucose,fructose,valine,tryptophan,salicylic acid,p-hydroxybenzoic acid and Vc,etc.;The main non-enzymatic browning type could be the polymerization of polyphenols during the late stage of fermentations and the ripening period of Msalais.?3?During the Msalais process,the technological factors differently effecting the non-enzymatic browning were incluing the brewing year,the extraction of grape residues or not,the concentration of grape juice with fierce fire or gentel fire,microbial community to strar fermentations and the levels of dissolved oxygen during fermentations.A preliminary comparison of the influence of various factors effecting on the non-enzymatic brown shwon the following:Concentration of grape juice with grape residuces>concentration of grape juice without grape residuces,concentration of grape juice with firece fire>concentration of grape juice with gentel fire,fermentation with high oxgen content>fermentation with low oxgen content.The fermentations with microbial comunitly from worshopes and plant microbial shown in different effects on the non-enzymatic browing,but there were significant differences between different vintage brewing.