Effects Of Linoleic Acid On Advanced Glycation End Products In Maillard Reaction Models

Advanced glycation end products(AGEs)are glycated metabolites that are produced in vivo and are associated with aging-related diseases.AGEs are also formed during food processing,and are generally accumulated in nutrient-rich foods,especially foods of lipid-rich.The presence of AGEs in food risks to human health.Due to the complexity and heterogeneity of the real food,the current research is not very detailed.Therefore,this paper adopts the simulation system closing to the real food,which aims to study the effect of linoleic acid(LA)on the AGEs in the simulation system and the mechanism of formation of AGEs.In this paper,two simulation systems were established,one was amino acid system:(1)D-glucose(D-Glc)+L-lysine(L-Lys)+LA;(2)D-Glc+L-lys;and another was protein system:(1)D-Glc+bovine serum albumin(BSA)+LA;(2)D-Glc+BSA.The effected of LA on the flavor,reaction intermediates and free radicals in the amino acid model system were discussed using electronic tongue(E-tongue),electron spin resonance spectroscopy(ESR),ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)and colorimetric method.The effected of LA on protein glycation and protein secondary change were studied by polyacrylamide gel electrophoresis(SDS-PAGE),infrared spectroscopy(FT-IR),conductivity,fluorescence chromatography and circular dichroism.The findings are as follows:1.E-tongue analysis showed that the addition of LA affected the change of bitterness and astringency(the flavor of representative polymers)and the increased in bitterness and astringency content which reflecting the increased of polymer content.Therefore,LA was a key factor in the reaction of flavor changed,while LA was also a key factor in triggering the glycation reaction.2.ESR analysis,there were high reactivity free radicals in GL,and these groups were mainly produced by maillard reaction(MR)components(D-Glc,L-Lys).The free radicals in GLY were mainly produced by LA oxidation rather than MR.Thus,LA promoted the formation of AGEs mainly through the LA peroxidation pathway,rather than the MR pathway.3.Analysis representative AGEs by UPLC-MS/MS and colorimetric,the results showed that AGEs mainly formed through the Strecker degradation reaction in the GL.In GLY,AGEs were produced by LA oxidation primarily,and LA produced greater amounts AGEs.4.SDS-PAGE analysis showed that the content of natural BSA decreased gradually during the process of glycation,and the content of protein polymer and crosslinking products increased gradually.LA promoted the cross-link,polymerization reactions more intense,and more AGEs were produced.5.FT-IR data showed that the a-helix of protein secondary structure in GB and GBY were lower than the natural BSA;and ?-fold was opposite.These showed that the participation of LA,promoted the secondary structure of BSA looser significantly,leading to protein glycation,crosslinking,polymerization reaction more intensely.6.As the reaction progressed,the conductivity of GB and GBY increased,but the conductivity of GBY was lower than that of GB,because the addition of LA would change the protein structure and produced polymerization products with larger molecular weight.7.With the reaction advancing,the fluorescence value of samples in GB and GBY appeared a regular reduction.The difference of fluorescence between GBY-0 h sample and GB-0 h sample was significant(p<0.01),which indicated that the addition of LA reduced the fluorescence value of the model.The absorption peak of samples in GBY had shift,which characterizesd the change of structure and new substances generated,indicating that the LA was the main factor in protein structure changed.8.CD was a method of quantitative analysis mainly in the far ultraviolet spectral region(190-250 nm)on glycation effect of the protein secondary structure.The results showed that the secondary structure of BSA in GB and GBY were loose and the change of GBY was more obvious.The experimental results were different from the natural BSA,indicating that LA has a catalytic effect on the glycation of protein,leading to a more pronounced change in secondary structure of BSA.The above experiments showed that LA has a great influence on the MR models(GL,GB),and the two conclusions are drawn:On the one hand,LA is the key factor of flavor change and can promote the formation of high reactive free radicals by the lipid peroxidation pathway which promotes the formation of AGEs.On the other hand,LA not only promotes the loosening of the secondary structure of BSA,but also leads to the increase of protein glycation,crosslinking and polymerization more obviously.