Study On The Changes Of Nutrients And Formation And Control Of Hazards In Chinese Dishes During Heat Processing

China has a long history of food culture,and traditional Chinese dishes are recognized as treasures of the nation's food industry.With social progress and economic development,the requests about flavor,sensory quality and safety have been demanded increasingly.Almost all Chinese dishes are treated by hightemperature,and due to complexity of food compositions,reactions including protein degradation,Maillard reaction and lipid oxidation will occur during heat processing,accompanied with formation of some heat-treated hazards.So it's necessary to study on changes of nutrients and formation of hazards in Chinese dishes during heat processing.Simplifing process of Chinese dishes,the subject investigated effects of temperature and time on the nutrients changes and hazards formation and tried to inhibit formation of heat-treated hazards by adding natural plant antioxidants.The main research contents of this paper are as follows:1.Investigated effects of temperature and time on the nutrients changes during roasting,deep-frying and pan-frying.Results showed that with the increase of temperature and time,protein content will get improved.As for fat content,long-time roasting can reduce its content,while there is an increase in long-time and high-temperature deep-frying or pan-frying.All the three kinds of cooking methods can influence the composition of fatty acids and amino acids,whereby roasting has few effects on the proportion of SFA,but deep-frying and pan-frying significantly reduce the proportion of SFA.Besides,temperature and time are also main factors which influence total amino acids composition.Increasing of temperature and time can improve various amino acids content,but the proportions of EAA and NEAA accounted for TAA don't have significant differences.Meanwhile analyzed the nutrients changes in sixteen kinds of Chinese dishes.To the majority,content of protein as well as PUFA/SFA value get improved largely after processing.Proportions of EAA accounted for TAA in the processed dishes are 43.07%?53.77%,ratios of EAA and NEAA are 0.757?1.163,which can completely reach the standard of 40% and 0.6 ruled by FAO/WHO.2.Investigated influences of temperature and time on formation of acrylamide,furan and TFAs in simplied dishes prepared with different cooking methods.It turned out that increasing of temperature during roasting has a promotive effect on the 3 kinds of hazards formation,and extension of time also shows an addition in furan and TFAs,but for acrylamide it has a inhibition effect.In deep-frying process,high temperature can also accelerate formation of acrylamide,but if it was treated for a long time under high temperature,then acrylamide will be polymerized and cause its content reduced.As for furan and TFAs,the increasing of temperature and time has a stimulative influence.In the process of pan-frying,temperature and time can promote the formation of acrylamide and TFAs,while lower the furan.The subject determined heat-treated hazards content in 16 kinds of processed Chinese dishes.Results showed that content of acrylamide ranges from 9.40 to 62.4 ?g/kg,furan content ranges from 1.5 to 10.5 ng/g and content of TFAs varies from 0.40 to 3.18 mg/g,.Besides,it's manifested that content of acrylamide and TFAs in stewing and boiling dishes are lower than that in deep frying.However the former cooking methods caused formation of a higher content furan.3.Explored inhibition of natural plant antioxidants on heat-treated hazards formation during cooking in braised pork in brown sauce.Results showed that antioxidants for hazards overall presented in the form of three kinds of phenotype: inhibition,inhibit + promotion and promotion.Antioxidant of bamboo leaves could largely inhibited the formation of furan,however showed a promotive effect to trans fatty acid and acrylamide.Tea polyphenol showed an obvious inhibition of TFAs and acrylamide,and it exsited an similar concentration-response relationship on formation of TFAs and AM.However,it improved the formation of furan.As for rosemary acid,it can dramatically reduce the formation of furan and there is a markedly dose-response relationship.But to TFAs and acrylamide,it clearly manifests promotion effect in low concentration and inhibition effect in high concentration.