Studies On The Effect Of Intrinsic Factors On Nonenzymic Browning Of Longan Juice

Nonenzymic browning commonly happened in longan juice druing processing and storage.The nonenzymic browning happened in the juice is caused by four kinds of reactions:Maillard reaction,Caramelization reaction,Ascorbic acid degration and the oxidation and condensation of polyphenol.The reactants of the four major recations such as sugars,amino acids,ascorbic acid and polyphenol can be seemed as the intrinsic factors of nonenzymic browning in longan juice.Variation of browning index,chroma index and the content of intrinsic factors of nonenzymic browning in longan juice during processing and storage were determined.The data were analyzed by stepwise regression and path analysis to conclude the effect of intrinsic factors on nonenzymic browning in longan juice. Through the studies above,conclusions were made as follows.1.The effect of intrinsic facotrs on nonenzymic browning of UHT longan juice during processingThe accumulation of HMF enhanced the browning index of UHT longan juice during processing indirectly.The decrease of Phe and Ser and the indirect effect of HMF reduced the luminosity of the juice.The increase of HMF reduced hunter a,however,the decrease of the polyphenol component whose retention time is 2.582min and Lys enhanced hunter a.The decrease of Arg reduced hunter b,whereas the decrease of Phe and the polyphenol component whose retention time is 2.783min enhanced hunter b.Ascorbic acid had the most significant effect on the accumulation of HMF in UHT longan juice during processing.The decrease of ascorbic acid promote the accumulation of HMF.The increase of polyphenol component whose retention time is 9.308min enhanced the amount of HMF as well.2.The effect of intrinsic facotrs on nonenzymic browning of atmospheric cooked longan juice during processingThe accumulation of polyphenol component whose retention time is 9.308min enhanced the browning index of atmospheric cooked longan juice during processing significantly.In the next place,the decrease of Phe made the browning index increase indirectly.The decease of polyphenol components whose retention time are 2.582min and 3.771min reduced the luminosity.In addition,the increase of polyphenol components whose retention time is 8.893min reduced the luminosity as well.The decrease of polyphenol component whose retention time is 2.582min and the increase of polyphenol component whose retention time is 8.893min enhanced hunter a.The accumulation of HMF and the decrease of the polyphenol component whose retention time is 2.785min and soluble protein enhanced hunter b.The decrease of the polyphenol component whose retention time is 50.979min was the most significant factor of promoting the accumulation of HMF.In the next palce,the polyphenol component whose retention time is 34.697min enhanced the accmulation of HMF indirectly.3.The effect of intrinsic facotrs on nonenzymic browning of UHT longan juice stored at 4℃The decrease of ascorbic acid,Gly,Cys-ss-cys and Lys enhanced the browning index in UHT longan juice stored at 4℃.Ascorbic acid had the most significant effect on browning index.Gly and Cys-ss-cys reacted with ascorbic acid to enhance the browning index.The decrease of polyphenol components whose retention time are 54.624min and 41.254min and Val made the luminosity descend.The descent of Gly and Asp and the indirect effect of fructose enhanced hunter a.;the indirect effect of Asp reduced hunter a. The decrease of ascorbic acid and the indirect effect of polyphenol component whose retention time is 41.254min enhanced hunter b.The stepwise regression euqation of variation of the content of HMF and nonenzymic intrintic factors was concluded: y_HMF=-0.55920+0.03247X_{9.308min polyphenol component}-0.11086X_sucrose+0.03475X_fructose4.The effect of intrinsic facotrs on nonenzymic browning of UHT longan juice stored at 28℃The stepwise regression euqation of variation of browning index and the content of and nonenzymic intrintic factors was concluded:y_{browning index}=161.80920+5.43135X_fructose -2.84350X_HMF-3.55082X_sucrose-0.07070X_{8.893minpolyphenol componen}.The decrease of Gly,Glu and Val reduced luminosity indirectly.The decrease of Ala,Gly and glucose reduced hunter a;the decrease of Asp enhanced hunter a.Decrease of Ile reduced hunter b.HMF was enhanced by the decrease of soluble protein and the increase of the polyphenol components whose retention time are 14.565min and 8.893min.5.The effect of intrinsic facotrs on nonenzymic browning of UHT longan juice stored at 60℃ The increase of the polyphenol component whose retention time is 29.359min enhanced the browning index significantly.In the second place,the increase of the polyphenol components whose retention time is 9.308min enhanced the browning index indirectly.The descent of the polyphenol components whose retention time is 54.624min lowered the luminosity indirectly.The drop of glucose and Lys and the indirect effect of Leu enhanced hunter a.The descent of Lys enhanced hunter b;the decrease of Arg and Tyr lowered hunter b.The increase of the polyphenol component whose retention time is 29.359min and the decrease of the polyphenol component whose retention time is 54.624min promoted the accumulation of HMF.The decrease of the polyphenol component whose retention time is 31.130min enhanced the accumulation of HMF as well.6.The effect of intrinsic facotrs on nonenzymic browning of atmospheric cooked longan juice stored at 4℃The accmulation of HMF enhanced the browning index.The indirect effect of Asp enhanced the browning index as well.Variation of ascorbic acid,Phe and Cys-ss-cys had negative correlation with variation of luminosity.The decrease of ascorbic acid and Phe lowered hunter a;the decrease of soluble protein enhanced hunter a.The descent of soluble protein reduced hunter b;the increase of ascorbic acid and sucrose enhanced hunter b.The polyphenol component whose retention time is 9.308min had the most significant effect on the accumulation of HMF.7.The effect of intrinsic facotrs on nonenzymic browning of atmospheric cooked longan juice stored at 28℃The decrease of sucrose,glucose and ascorbic acid enhanced the browning index. The decrease of sucrose lowered luminosity.The decrease of ascorbic acid enhanced hunter a;the accumulation of HMF reduce hunter a.The increase of the polyphenol component whose retention time is 12.245min and the decrease of Cys-ss-cys enhanced hunter b.The increase of the polyphenol component whose retention time is 14.565min and the descent of Asp and the polyphenol component whose retention time is 37.379min reduced the accumulation of HMF.8.The effect of intrinsic facotrs on nonenzymic browning of atmospheric cooked longan juice stored at 60℃The indirect effect of the polyphenol component whose retention time is 54.624min and Cys-ss-cys enhanced browning index.The increase of the polyphenol components whose retention time are 12.245min and 8.893min and the decrease of ascorbic acid reduced luminosity.The accumulation of HMF enhanced hunter a.The increase of the polyphenol component whose retention time is 9.308min enhanced hunter b;the decrease of ascorbic acid and Phe reduced hunter b.The decrease of ascorbic acid and His and the increase of the polyphenol component whose retention time is 29.482min promoted the accumulation of HMF.