Formation Regularities And Inhibition Mechanism Of Phip In The Microwave Heating

Heterocyclic aromatic amines(HAAs)are carcinogenic/mutagenic substances produced in heated meats,and 2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine(Ph IP)has attracted wide attention as one of the most abundant HAAs.The formation mechanism and influencing factors of PhIP under conductive heating has been reported in detail,and the inhibition pathways based on polyphenols have gradually become a consensus.As a rapid heating method directly acting on dielectric materials,the formation process of PhIP in microwave heating has not been resolved.And due to the microwave sensitivity of the hydroxyl group of polyphenolic compounds,it has the unpredictable Ph IP inhibitory effects and mechanisms in microwave heaing.Based on the above issues,this study established methods for the comparison of microwave heating and conductive heating,optimized the detection method for PhIP chemical system,explored the effects of different factors on Ph IP formation,and investgated the inhibition mechanism of quercetin on PhIP from two aspects of electromagnetic response and chemical change mechanism.Finally verified in a real food system.(1)Establishment of sample preparation and detection methods for Ph IP chemical system.For the pretreatment process of the PhIP chemical system samples,the reaction solution was freeze-dried first,then extracted with alkaline ethyl acetate,and finally dried directly for detection.For detection,0.1% formic acid water was used as the mobile phase and BEH phenyl column was used as the column.Results showed that the method not only shortened the time,but also had good repeatability,and was validated in conductive seal heating.(2)Study on the formation regularities of Ph IP in microwave field.The influence of the object and condition factors on Ph IP formation was studied.Results showed that the content of Ph IP increased with heating time and temperature,the influence of microwave power on PhIP was small.Among six polyphenols(quercetin,chlorogenic acid,p-coumaric acid,luteolin,kaempferol,and apigenin),quercetin had the best inhibitory effect on PhIP,up to 60%.The presence of PhIP was confirmed in microwave-heated beef,and Ph IP content was significantly reduced after addition of quercetin-containing onions.(3)Electromagnetic response mechanism of quercetin and other polyphenols(luteolin,kaempferol,apigenin)in microwave field.The dielectric properties,electrical conductivity,and reflection loss of the four polyphenols were measured.Results showed that the difference of dielectric constant and dielectric loss between the four polyphenols was small.The dielectric constant of quercetin decreased with increasing concentration and temperature,and the dielectric loss increased with the concentration and decreased with temperature.Luteolin had the largest electrical conductivity and reflection loss,followed by quercetin.The electromagnetic response characteristics of quercetin and other polyphenols were in accordance with electromagnetic laws,but there was no significant correlation with the inhibition effect.of Ph IP.(4)The chemical mechanism of quercetin inhibiting Ph IP formation in microwave field.The inhibition mechanism of quercetin on PhIP formation under conductive heating was used as a reference to explore the production of quercetin-phenylacetaldehyde adducts in microwave field.Results showed that quercetin-phenylacetaldehyde adducts were present in microwave field,and it increased with quercetin concentration,but the ability of quercetin trapping phenylacetaldehyde gradually decreased with the heating time,and quercetin concentration promoted adducts formation more than heating time.Finally,quercetin-phenylacetaldehyde adducts were detected in quercetin-containing onion/beef system in microwave heating.In summary,it was confirmed that PhIP was produced during microwave heating.Quercetin could inhibit Ph IP formation in microwave field,and the inhibitory effect was stronger than that of conductive heating.The inhibitory process was in accordance with the pathway of polyphenol-activated carbonyl compound addition and accumulation.There was no direct correlation between the synergistic effects and changes in the apparent electromagnetic response,and further study was needed.