| Heterocyclic aromatic amines (HAAs) are carcinogenic and mutagenic polycyclic aromatic compounds formed during processing of meat products at high temperature. Their formation is greatly dependant on several factors including kinds of meat, processing method, cooking temperature and duration and concentration of precursors. At present, the production of Chinese traditional braised chicken is still followed by high-temperature frying and recycled soup boiling process, which special processing method made products a unique flavor, but also may enhance the formation of HAAs. Studies on HAAs in Chinese traditional braised chicken have not been seen up to now. The objectives of the present study were to develop a method for determination of9HAAs in braised chicken, and to evaluate effect of processing conditions and spice extracts to the formation of HAAs in braised chicken. The contents and results are as follows:1Determination of9HAAs in braised chicken by solid-phase extraction-high performance liquid chromatographyA method was developed for the simultaneous determination of9HAAs in Chinese traditional braised chicken using solid-phase extraction-high performance liquid chromatography (SPE-HPLC). The performance of3different organic extraction solutions,2solid phase extraction procedures,3different reversed-phase columns and5different mobile phases were tested for optimizing separation conditions of the9HAAs from braised products. In the end, ethyl acetate was selected as the extraction solution, and the extract was purified with propylsulfonic acid silica (PRS) and C18SPE columns. The analysis was performed on a TSK-gel ODS-80TM column using a gradient elution with the mobile phase of0.05mol/L aqueous acetic acid-ammonium acetate buffer (pH3.4) and acetonitrile. The results showed that the average recoveries (n=6) of the9HAAs spiked in meat samples at3levels ranged from43.29%to90.55%with the relative standard deviations (RSDs) between0.49%and9.47%, and the limits of detection (LODs, S/N=3) were in the range of0.1-3.6μg/kg. The method is simple, rapid, accurate and sensitive enough for the analysis of HAAs in Chinese traditional braised chicken.2Effect of processing conditions to the formation of HAAs in braised chickenRaw chickens were processed following the traditional method. Effect of frying time, honey concentration, boiling time and recycled soup boiling times to the formation of9HAAs in braised chicken were studied. The results showed that9H-pyrido[3,4-b]indole (Norharman),1-methyl-9H-pyrido[3,4-b]indole (Harman) and3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) were detected in fried chicken. An increased order was found for the HAAs in fried chicken meat and skin along with increasing frying time (p<0.05). The total amounts of HAAs in chicken meat and skin fried for8min increased by232.3%and758.6%, respectively compared to that fried for1min. The amount of Norharman in fried chicken skin was increased with honey concentration (p<0.05), Norharman content in fried chicken skin which were covered with100%honey was71.4%higher than the control sample. Honey had no significant effect on the formation of HAAs in fried chicken meat (p>0.05). It was found that both boiling time and recycled soup boiling times significantly affected the formation of HAAs in braised chicken meat and skin (p<0.05). An increased order was found for the HAAs in boiled chicken meat and skin along with increasing boiling time. The amounts of Norharman, Harman, Trp-P-2and Trp-P-1in chicken meat and skin boiled for6h increased by376.3%,800%,691.7%,777.5%and205.3%,218.5%,391.2%,651.8%, respectively compared to that boiled for0.5h. When recycled soup was boiled for20times, total content of HAAs in chicken meat and skin was60.64and103.29ng/g, respectively, it was1029.2%and1161.2%higher than that just boiled for1time. Furthermore,2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were detected in chicken meat and skin boiled with soup which was boiled for20times.3Effect of spice extracts to the formation of HAAs in braised chickenIn order to evaluate the effect of spice extractions to the formation of HAAs in braised chicken,5spices which have strong antioxidant activity were selected from12spices. The extraction technology of polyphenols in clove was optimized. The results showed that water extract of clove had the strongest antioxidant activity of all spices. The optimization extraction technics parameters were as follows:clove was extracted at70℃in water for40min, with1:20as ratio of solid/liquid. Clove extract could inhibit the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in braised chicken, but could not inhibit the formation of Norharman and Harman. Marinating time significantly affected the formation of PhIP in braised chicken meat (p<0.05), PhIP content in chicken meat marinated with clove extract for5and6h decreased by44.4%and38.9%, respectively compared to the control sample. Marinating time had no significant effect on the formation of PhIP in braised chicken skin (p>0.05). Polyphenol concentration of marinade had no significant effect on the formation of PhIP in braised chicken meat and skin (p>0.05). An increased order was found for Harman in chicken skin along with increasing polyphenol concentration of marinade (p<0.05). |
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