Oxidation combined with Maillard reaction induced free and protein-bound N^ε-carboxymethyllysine and Nε-carboxyethyllysine formation during braised chicken processing

The objective of this work was to investigate the effects of oxidation and Maillard reaction on free and protein-bound N^ε-carboxymethyllysine(CML)and Nε-carboxyethyllysine(CEL)formation during braised chicken processing.It was found that a positive correlation was observed between carbonyl,fat oxidation,Maillard reaction,CML and CEL(P<0.05).The sulfhydryl groups could be used as potential indicators to evaluate the compounds’interaction levels between Maillard reaction and protein oxidation.Frying promoted the formation of lysine(Lys),glyoxal(GO)and methylglyoxal(MGO)(P<0.05);boiling enhanced the formation of GO and MGO(P<0.05)while inhibited the levels of Lys(P<0.05);sterilizing blocked the formation of MGO and Lys(P<0.01)but improved GO levels(P<0.05).Finally,a perspective was concluded that the Maillard reaction combined with oxidation is one of the main reasons for the formation of free and protein-bound CML and CEL during braised chicken processing.

The effect of protein oxidation on the formation of advanced glycation end products after chicken myofibrillar protein glycation

Investigation that protein oxidation to the formation of advanced glycation end products(AGEs)after chicken myofibrillar protein glycation is limited.Models of protein oxidation induced by different concentrations of hydroxyl radicals(·OH)were developed after the chicken myofibrillar protein mild glycation(MPG).Results exhibited that levels of AGEs and surface hydrophobicity(H_(0))steadily increased with the a ddition of h ydrogen peroxide(H_(2)O_(2))concentration.However,levels of s ulfhydryl group,free amino group,and particle size gradually decreased with the H_(2)O_(2)concentration.The protein carbonyl value increased in H_(2)O_(2)concentration until 10 mmol/L.Pearson's correlation indicated that MPG structure modification(unfolding and degradation)induced by protein oxidation were significantly positively correlated with AGEs concentration(P<0.05).Finally,a mechanism was proposed to hypothesize t he effect of protein oxidation on the formation of AGEs under MPG conditions.

Effects of oxidation and precursors(lysine,glyoxal and Schiff base)on the formation of Nε-carboxymethyl-lysine in aged,stored and thermally treated chicken meat

Advanced glycation end products(AGEs)might pose health risks,and processing and storage could accelerate the generation of AGEs in meat.However,limited few reports indicated the changes of AGEs contents in meat during storage.In this study,the aim is to investigate the oxidation and precursors and their roles in the formation of N^(ε)-carboxymethyl-lysine(CML)in raw and cooked chicken meat after post-mortem ageing and storage.As post-mortem ageing and storage time increased,the CML content in cooked chicken breast significantly increased from 1.81 mg/kg to 2.00 mg/kg during 0-6 h,and then decreased from 2.00 mg/kg to 1.80 mg/kg during 6 h-1 day,finally increased again during 1-7 days,while the CML contents of raw and cooked leg significantly and continuously increased from 1.78 mg/kg to 2.08 mg/kg.Furthermore,CML was extremely positively correlated with fat oxidation(R^(2)=0.793,P<0.01),protein oxidation(R^(2)=0.917,P<0.01)and glyoxal(R^(2)=0.678,P<0.05),and was negatively correlated with lysine(R^(2)=0.536,P<0.05).No significant correlation was observed between the Schiff base and CML.

Formation of advanced glycation end products in raw and subsequently boiled broiler muscle:biological variation and effects of postmortem ageing and storage

The study aimed to investigate and compare the contents of carboxymethyllysine(CML)in two kinds of broilers during postmortem ageing and storage.The contents of CML in raw and boiled(100℃,30 min)broiler briskets and legs which were from white feather broilers(n=8)and yellow feather broilers(n=8)with ageing and storage at 4℃for 0-168 h were determined.Postmortem ageing and storage had a significant(P<0.05)effect on the color and A;in both boiled broilers meat.In addition,with the ageing and storage time increasing,CML content in raw white feather broiler brisket meat had no significant(P>0.05)change,while that in boiled brisket meat significantly(P<0.05)increased during 0-6 h,then decreased during 6-24 h,finally increased again.CML content in leg meat increased significantly(P<0.05)with the ageing and storage time prolonging.But postmortem ageing and storage had no significant(P>0.05)effect on the CML contents in raw/boiled yellow feather broilers.Meanwhile,CML contents in white feather broilers were much higher than that in yellow feather broilers.Thus,white feather broilers can be selected as the research object to study the mechanism of ageing and storage on CML content in the postmortem broiler in the future.

Monitoring and identification of spoilage-related microorganisms in braised chicken with modified atmosphere packaging during refrigerated storage

This study mainly monitored the dominant bacterial populations and identified the spoilage-related microorganisms of braised chicken meat stored under different CO_(2)-modified atmosphere packaging(MAP)during refrigerated storage using a culture-dependent method and 16S rDNA identification.The quality changes and shelf life of the meat were also measured.The growth rate of total viable count(TVC)in braised chicken was slower with an increase of CO_(2) content in MAP,which also occurred in the remaining bacterial species monitored(lactic acid bacteria,Pseudomonas spp.,Brochothrix thermosphacta).The MAP exerted beneficial effects on the quality of braised chicken,as demonstrated by retarding the production of total volatile basic nitrogen(TVB-N)and delaying lipid oxidation(TBARS test).A total of 14 isolates were identified from braised chickens with different packaging at the end of storage,these included P.fragi(6 isolates),P.psychrophila(2 isolates),Enterococcus faecalis(3 isolates),B.thermosphacta(2 isolates),Staphylococcus equorum(1 isolate).