Non-enzymatic Browning Of Ascorbic Acid During Storage Of Blueberry Juice

This paper systematically studies the factors affecting the non-enzymatic browning of ascorbic acid under different storage conditions.At the same time reveal the maillard reaction,anti-oxidative decomposition of ascorbic acid,caramelization and polyphenol oxidation decomposition during storage of blueberry juice.It explores the influence from four aspects,pH,metallic ion,beam and inhibitor,to the non-enzymatic browning of ascorbic acid system about blueberry juice.The kinetic analysis of ascorbic acid non enzymatic browning system about blueberry juice does reference for study of non-enzymatic browning about blueberry juice.The main results are as follows:(1)The construction of three kinds of blueberry juice system.At first selecting the concentration of 12%trichloroacetic acid as terminator add to blueberry juice,which constitutes the 1 sample system.In 1 based system,we add 10%D001 cation exchange resin and the static adsorption time is 16 h,which constitutes the 2 sample system.In 1 based system,we add 200 ?g/g sodium bisulfite,which constitutes the 1 sample system.The brown stain of blueberry juice becomes more serious with the extension of storage time and temperature increasing.The 5-hydroxymethyl furfural is the key indicators,and by using phase subtraction is analyzed.The resolve shows that the decomposition reaction of ascorbic acid oxidation is the major factor of the non-enzymatic browning of blueberry juice.Other reactions' contribution are smaller.(2)The analysis of factors lead to non-enzymatic browning because of the decomposition reaction of ascorbic acid in the storage of blueberry juice.The result shows that:when pH=2,the ascorbic acid does not resolve.When pH>3,the ascorbic acid is not stable and easily resolves happening brown stain.When pH=4,the brown stain is most serious.The metalion Al3+?Fe2+?Fe3+?Cu2+ and Zn2+ promote the oxidation of ascorbic acid.Iron and copper have the most significant effect,others take second place.Sn2+?Ca2+ and Mn2+ has the inhibitory effect.The inhibitory effects are Sn2+>Ca2+>Mn2+.Light conditions can promote the oxidation of ascorbic acid.The values of browning index A420 are all bigger than the values of browning index A420 of hidden sample.Do the single factor concentration screening test.At last confirm three kinds of inhibitors:0.03%phytic acid,0.05%citric acid and 0.05%Vb-Na.Separately add to the blueberry juice ascorbic acid non enzymatic browning system.After storage,we compare them,and we can get that these three kinds of inhibitors have inhibitory effect on blueberry juice.The influence is citric acid>Vb-Na>phytic acid.(3)By building the non-enzymatic browning system of blueberryjuice ascorbic acid,the relevant indicators(4,25? and 37?)of blueberry juice during storage were determined by using the zero-order,first-order and composite dynamics model fitting,browning index BI complied with composite dynamics model.The ascorbic acid constantly degraded in the process of storage,which met the first-order kinetics model,while the content variation of 5-HMF met the composite dynamics model.The indexes with the change of temperature were reflected according to the Arrhenius equation for linear fitting.The generation of 5-HMF and browning index BI showed good linear relationship(R2?0.949)at three different storage temperatures.