The Formation Of Norharman And Harman In Braised Sauce Meat

High concentration of co-mutagenic norharman and harman formed in braised sauce meat. Theformation of norharman and harman were studied to decrease the content of norharman and harman andto research and develop new braised sauce meat products with low content of heterocyclic aromaticamines. The levels of heterocyclic aromatic amines in34kinds of meat products of7different reginswere investigated. The potential souce of norharman and harman in braised meat, which contained thehighest concentration of norharman and harman, were studied. The effects of possible precursors on theformation of norharman and harman in braised sauce meat were studied by adding differentconcentrations of tryptophan, phenylalanine, creatine and glucose. Model systems at a low temperature(100℃) were established to study the formation of norharman and harman and to speculate the possiblemetabolic process.(1) In the present study, nine HAAs were analyzed in34kinds of meat products consumed inChina. The total HAAs contents in34kinds of meat products ranged from4.14to108.80ng/g. Drymeat and sauced meat contained the highest concentration of total HAAs compared with the other kindsof meat products, while fried meat contained the lowest concentration of HAAs. Samples from East andNorthwest China showed higher concentration of total HAAs than other regions. Meat products fromSouthwest China contained the lowest concentration of HAAs. Two of the most common specific HAAswere norharman and harman. They were detected in all meat products, with the levels of1.19~62.30ng/g and1.09~63.97ng/g, respectively. While the concentration of MeIQx, PhIP,4,8-DiMeIQx, AaCwere much lower. Trp-P-2, IQ and MeAaC were detected in part of the samples.(2) The potential sources of co-mutagens β-carbolines norharman and harman in braised saucemeat were investigated. The occurrence of the bioactive β-carbolines in six braised sauce meats and fivesoy sauces were studied by solid-phase extraction and HPLC-DAD. Furthermore, the potential sourcesof β-carbolines in braised sauce mutton boiled with one of the soy sauces were determined. β-carbolineswere detected in all of the six braised sauce meats and five kinds of soy sauces. The concentrations ofharman in braised sauce meat were3.71~42.32ng/g, and norharman were2.95~63.97ng/g. The levelsof norharman and harman in soy sauces were74.71~199.27ng/g and111.47~301.30ng/g, respectively.Raw mutton contained undetectable amounts of norharman and harman. The proportion of norharmanand harman in boiled mutton was23%and15%. The percentage of norharman and harman by boilingsoy sauce and seasonings was46%and58%, respectively. Mutton reacted with soy sauce generated27%harman and31%norharman.(3) Effects of possible precursors (tryptophan, phenylalanine, creatine and glucose) on theformation of norharman and harman were studied. The results showed that the amount of norharmanand harman in braised sauce meat and soup rose with increasing levels of tryptophan. With2.4mmoltryptophan, the total amount of norharman and harman in both sauced meat and soup was3.85times,2.33times that in the blank control group. With a few exceptions (1.2mmol), phenylalanine did notshow any consistent effect of concentration on β-carboline. Creatine with a low level (0.12mmol) had a strong influence on the formation of β-carboline in braised sauce meat and soup rather than high level.The content of norharman and harman increased and then decreased with the increasing level ofglucose.(4) The formation of co-mutagens norharman and harman in different time of six model systems ata low temperature (100℃) were studied. Results showed that both norharman and harman wereobserved in the model systems of tryptophan, tryptophan-creatine and tryptophan-creatine-glucose. Inaddition, the amounts of norharman and harman increased with increasing heating time (P＜0.05). Theconcentration of norharman and harman after heating3h at100℃were129.11ng/g and9.28ng/g,respectively. Heating tryptophan and glucose formed a large amount of norharman and harman. In thismodel system, the concentration of norhaman and harman heated for3h, were9times and102timesthat in the tryptophan model system, respectively. The model system of tryptophan-creatine-glucosemainly formed norharman as well. The content of norharman and harman at the heating time of3h were699.09ng/g and29.5ng/g, which were5times and3times that in tryptophan model, respectively.However, they just accounted for58%and3%of the level of norharman and harman in thetryptophan-glucose model system, respectively. In conclusion, low temperature heating model systemscontained tryptophan could always form co-mutagens norharman and harman.