Effects Of Low Temperature Vacuum Heating On The Formation Of AGEs In Sturgeon Fillets And Its Regulatory Mechanism By Tea Polyphenol

Advanced glycation end products(AGEs)are generated from the interaction of protein amino groups with reducing sugar carbonyl groups under non-enzymatic conditions.In addition to the endogenous AGEs,the accumulation of dated AGEs can also exacerbate the occurrence of chronic diseases,such as diabetes and kidney disease.This work was to study the effect of low temperature vacuum heating(LTVH)technology on the formation of AGEs in sturgeon fillets,and analyze the mechanism of inhibition via tea polyphenol.The main results were as follows:(1)Compared with the control group(TC),LTVH fillets were obtained better edible qualities,but higher concentration of AGEs.The color and flavor of LTVH fillets were improved due to addition of tea polyphenol.Furthermore,the concentrations of AGEs in LTVH fillets were decreased effectively as well as tea polyphenol was added.However,the inhibitory on AGEs depended on the concentration of tea polyphenol.The concentrations of free CML,free CEL and bound in LTVH fillets were declined significantly(P<0.05)when tea polyphenol was20,200 μg/m L.However,when it was 2000 μg/m L,the concentration of free CML was increased.(2)Proteomics technologies were used for analyzed the glycosylation types and glycosylation sites of myofibrillar proteins in vitro model.And the results indicated that,higher numbers of glycosylation-modified proteins,glycosylation sites and glycosylation types were presented in samples with the high temperature.The number of proteins identified in the high temperature treatment group was as high as 143,which was much higher than that in the 60 ℃ treatment group(49).The number of glycosylation proteins in 6015B/G was declined due to the addition of tea polyphenols,which were 34,70,respectively.Furthermore,the numbers of pyrroline-modified,CML-modified,and CEL-modified glycosylated proteins of 6015B/G were 0,31,and10,respectively,which were lower than those group without tea polyphenols(9,42,and 12).(3)The Pearson correlations were used for analyzing the changes of amino acids and AGEs precursors in vitro glycosylation/anti-glycosylation models.And the results of showed that,the interaction between glucose and the amino group of myofibrillar proteins generated AGEs,and the reaction was aggravated at higher temperature,resulting in more Amadori products and α-dicarbonyl compounds.However,as tea polyphenols was added,it competes with the glucose for binding free amino groups of protein,occurring the reduction of the binding sites between glucose and protein,resulting in the declined of Amadori products and α-dicarbonyl compounds,and inhibiting the formation of AGEs.However,the inhibitory of tea polyphenols is weakened at high temperatures.(4)The content of EGCG tea polyphenol used in this experiment was as high as94%.The results of molecule docking showed that there was the non-covalently bound between EGCG and protein due to the benzene ring and phenolic hydroxyl group of EGCG.The results of chemical force also indicated that ionic bonds,hydrogen bonds and hydrophobic were the main chemical forces of glycosylation model at beginning thermal treatments.However,hydrophobic and disulfide bonds turned to be the dominant forces at the later stage of thermal treatment;Fourier infrared results also show that the secondary structure of the myofibrillar proteins had changed from α-helix to β-folds and β-turns.The resulted of isothermal titration calorimetry also indicted that there was a process of exothermic entropy increase when tea polyphenols were binding to sturgeon myofibrillar protein,and one molecule of protein can bind to 10-11 molecules of tea polyphenol.