The Formation Kinetics And Mitigation Strategies Of Benzo [a] Pyrene During Food Processing

Barbecue food is popular among the public due to its good taste and unique flavor.Heating at high temperatures gives the barbecue an attractive taste and good flavor,but also some harmful chemicals such as polycyclic aromatic hydrocarbons,heterocyclic amines,etc are formed at the same time.Benzo[a]pyrene（Ba P）is the most representative carcinogen in polycyclic aromatic hydrocarbons,which is harmful to human health.Therefore,in order to improve food safety,this thesis carried out research on the formation pattern and mitigation strategies of Ba P in heat processed food.An efficient and sensitive electrochemical detection method was developed based on Fe₃O₄,MWCNTs-COOH,and Nafion signal amplification electrochemical sensor.The food simulation system for the formation of Ba P in roasted meat was constructed using pork freeze-dried powder as the substrate,and the formation kinetics of Ba P have been investigated.The influencing factors and mitigation strategies for the formation of Ba P in roasted meat were explored and analyzed.The results as follows:（1）The Fe₃O₄/MWCNTs-COOH/Nafion electrochemical sensor was prepared by immobilizing magnetic nanosized Fe₃O₄/MWCNTs-COOH/Nafion on glass carbon electrode.A rapid and sensitive method for the determination of Ba P in roasted meat products has been developed.The electrochemical behavior of Ba P on different sensors was investigated and the sensors were characterized by cyclic voltammetry technology,impedance technology and TEM technology.The results showed that a well-defined oxidation peak was observed but no reduction peak appeared,which indicated the Ba P redox process was irreversible.And the prepared electrochemical sensor has good electrocatalytic performance,which significantly increases the Ba P oxidation peak current.At the same time,the modification and detection conditions were optimized,and the results as follows:The electrolyte is a solution of disodium hydrogen phosphate and potassium dihydrogen phosphate,with a p H of 2.5.The optimal immobilized membrane material is 0.5%Nafion solution,and the amount of modification solution is 6μL（2 mg/m L）,enrichment time is 15minutes.Under the optimal conditions,the oxidation peak current of Ba P was a good linear relationship with its concentration in the range of 0-100 nmol/L（R²=0.9970）,with a detection limit of 3.12×10^?10 mol/L（S/N=3）.The developed method was used to determine Ba P in barbecued pork samples,with recoveries ranging from 86.65%to 96.97%.Compared with High Performance Liquid Chromatography,this method has the characteristics of short sample preprocessing time and fast detection speed.And the prepared electrochemical sensor has good stability and reproducibility,so this method can be applied to the rapid and sensitive detection of Ba P in food.（2）A food simulation system for Ba P formation in roasted meat products was constructed using pork freeze-dried powder as the substrate.The effects of different components and temperatures on the formation of Ba P in the reaction system were investigated,and the formation kinetics were analyzed.Different fatty acids have different effects on the formation of Ba P.Compared with stearic acid,more Ba P is formed in the sample added with oleic acid and linoleic acid,that is,unsaturated fat are easier to be thermally decomposed to form Ba P than saturated fatty acids.The effects of different proteins on the formation of Ba P are also different.The amount of Ba P formation in the samples added with myofibril protein was much higher than that of sarcoplasmic protein and collagen.The formation of Ba P in systems with different proportions of fatty acids conformed to the first-order kinetic model.The first-order kinetic model can better predict the formation of Ba P in protein systems with different proportions.Moisture content has a significant impact on the formation kinetics of Ba P.The formation of Ba P in samples with75%and 50%water content conforms to the first-order kinetic model,while the formation of Ba P in samples with 25%water content is more in line with the zero-order kinetic model.Temperature significantly affects the formation of Ba P in the reaction system,and the amount of Ba P increases with the increase of temperature and time.At the same heating time,the higher the temperature,the greater the amount of Ba P formed.The first-order kinetic model can well fit the formation pattern of Ba P at different temperatures.The above results provide reference for the formation of Ba P under different conditions.It provides the basis for the optimization of subsequent meat heat-treated technology and formula.（3）The research object is Ba P formed during the barbecue process.The influences of heat-treat methods,raw material pretreatments,product formula and UV irradiation treatment on Ba P formation in roasted pork were invetigated.Different heating methods such as microwave,electric grilling,air frying,and frying have different effects on the texture and color of grilled meat.Compared with other heat-treat methods,the amount of Ba P formed in the air frying group and the microwave group is less.Both power and time have a significant impact on Ba P formation.As the heating power increases and the heating time prolongs,Ba P begins to gradually form and accumulate.When the heating is terminated,the amount of Ba P formed reaches its maximum.Pork with high fat content formed significantly more Ba P during heating.Different curing treatments（salt,beer,and different p H marinades）have different effects on the formation of Ba P in roasted meat.Among them,the reduction and mitigation effect of calcium salts is superior to other salts.The formation of Ba P in the black beer treatment group is the lowest.Compared to alkaline marinade,acidic marinade effectively slows down the formation of Ba P.Curcumin,quercetin,catechin,sesamol,and tea polyphenols all have obvious inhibitory effects on the formation of Ba P.Among them,tea polyphenols have the strongest inhibitory effect,with an inhibition rate of 36.35%～63.65%.The residual Ba P in roasted meat is degraded after being treated with UV radiation.As the irradiation time increases,the Ba P content in the sample significantly decreases.The above results provide a certain reference for the reduction and mitigation strategies of Ba P in roasted meat.