Effects Of Spices On The Amounts Of Advanced Glycation End-products In Stewed Meat Products

Advanced glycation end-products?AGEs?,such as N^?-carboxymethyllysine?CML?,N^?-carboxyethyllysine?CEL?and pyrrolidine,is a group of relatively stable compounds generally produced from non-enzymatic modifications of proteins or protein derivatives by reducing sugars or sugar derivatives.Dietary AGEs was initially believed to be part of the end products of the maillard reaction.However,subsequent studies have shown that in the early stages of the maillard reaction,the autooxidation of reducing sugars or the oxidative degradation of schiff bases could produce highly active dicarbonyl compounds,which could bind to proteins through covalent bonds to form AGEs.AGEs may also be produced during lipid peroxidation and ascorbic acid oxidation.Stewed meat products?Jiang-lu meats?are traditional Chinese foods,which are normally produced through pre-cooking,marinating,slow heating,and flavoring with soy sauce.Jiang-lu meats normally have tender texture and rich flavor and are among the most popluar meat products in China.Jiang-lu meats are rich in fat and protein and require long-time heating during their preparation,which generally result in rather high levels of AGEs in these products.The accumulation of dietary AGEs in the human body is related to the aging of the body and the increasing risks for some chronic diseases?such as Alzheimer's,hypertension,etc.?.Therefore,the levels of dietary AGEs,factors affecting their formation as well as effective measures for controling the amounts of dietary AGEs have become one of the hottest research areas in food safety.However,there is an overall lack of study on AGEs in Jiang-lu-rou.Therefore,the goal of this study was to apply ultra-high performance liquid chromatography-tandem mass spectrometry?UPLC-MS/MS?combined with the isotope internal standard of CML and CEL to analyze AGEs in Jiang-lu meats to under the general levels of AGEs in these products and the effects of some commonly used spices on the formation of AGEs in Jiang-lu meats.The following studies were included:1.Daily freshly made Jiang-lu beef collected from street vendors?n=11?and vacuum-packed Jiang-lu beef collected from supermarkets?n=8?were used in this study.Each sample was ground and mixed well before used for AGEs analysis with UPLC-MS/MS.In addition,the colors?Lab*system?of the cross section of a beef sample and its ground form were analyzed with a colormetry.The results showed that commercial Jiang-lu beef products had rather low amounts of free CML?0.29±0.01mg/kg-0.76±0.01 mg/kg,0.51±0.16 mg/kg?and CEL?0.34±0.01 mg/kg-0.93±0.02mg/kg,0.60±0.22 mg/kg?contents,but contained very high levels of protein-bound CML?19.58±0.97 mg/kg-114.33±7.55 mg/kg,41.98±26.78 mg/kg?and CEL:19.20±1.07 mg/kg-86.97±2.33 mg/kg,36.43±19.87 mg/kg).There was also great disparity in the protein-bound CML and CEL among individual products.There was no linear relationship between the contents of free CML and free CEL,but a good linear relationship?R²=0.85?was found between proten-bound CML and CEL.In addition,the levels of protein-bound CML and CEL in Jiang-lu beef varied among products from different batches.It was found that the CML contents in four beef products from the second batch were 87%,153%,103%and 78%,respectively,of those from the first batch,and the corresponded CEL were 88%,144%,142%and116%,respectively.The color of beef?L*,27.44±3.66-57.10±1.32;a*,8.71±1.27-25.23±0.99;b*,8.18±1.48-24.05±0.56?has no relationship with their contents of CML and CEL.2.The UPLC-MS/MS method was used to determine the amounts of protein-bound AGEs in pork products and in nine commonly used spices?star anise,fennel,cinnamon,bay leaves,galangal,angelica root,orange peel,fructus tsaoko,cardamom?.The effects of these nine spices on the contents of protein-bound CML and CEL were evaluated and the optimum cooking time?100?,60 min?of star anise,fennel,cinnamon and fructus tsaoko were decided.In addition,the effects of four spices composed of star anise,fennel,cinnamon and fructus tsaoko and the above nine spices and salt on the formatoin of CML in pork during heating?100?,60 min?were studied.The results showed that spices contained protein-bound CML?0²120?g/kg?and CEL?0³590?g/kg?.Among the nine tested spices,angelica root had the highest levels of CML?2120?g/kg?and CEL?3590?g/kg?,but no CML or CEL was detected in fennel.Heat treatment significantly increased the content of CML in pork,resulting in 1.98 times?100?,10 min?and 9.58 times?100?,60 min?as much as that of the raw meat.Star anise,fennel,cinnamon and fructus tsaoko had inhibitory effects on protein-bound CML in heat treated pork?121?,10 min?,leading to 23%?star anise?,17%?fennel?,10%?cinnamon?and 17%?fructus tsaoko?reduction,respectively.3.The amounts of protein-bound CML and CEL in pork formed during heating?100?,5,10,20,40 and 120 min?as affected by bay leaves,galangal,angelica root powder were evaluated in addition to the formation kinetic of CML and CEL during heating.The results showed that heating promoted the production of AGEs,which continuously increased during heating.The content of AGEs in pork after being heated for 120 min was about 5–8 times as much as that of raw meat,leading to35.60±2.20–40.68±5.66 mg/kg of CML and 13.32±1.49–16.85±2.44 mg/kg of CEL in pork.During the first 40 minutes of heat treatment,the formation of CML(R²=0.971–0.996;k=0.355–0.590 mg/kg min^-1)and CEL(R²=0.942–0.997;k=0.150–0.368 mg/kg min^-1)in pork with or without spice could be considered as zero order reaction.The effects of each spice on the formation of AGEs in meat during heating varied with the change of spices,heating time and the batch of meat used.The influence of each spice on the formation of CML in pork during heating is minor,however,all three species could promote the formation of CEL in pork during heating,especially the content of CEL in 5 min heat treated meat,which increased by13%–61%as compared to their control counterparts.The results of this study could help better control the formation of AGEs in Jiang-lu meats during thermal processing and eventually help to improve the safety and quality of meat products.