| Beef jerky, a unique food in our country, is shelf-stable, high-protein, low-fat and rich-nutrient. However, the special processing method of beef jerky is easy to promote the formation of heterocyclic aromatic amines (HAAs). HAAs are carcinogenic and mutagenic polycyclic aromatic compounds formed during processing of meat products at high temperature. Report about HAAs in beef jerky has not be seen at present, so, the objectives of this paper were to optimize a method for determination of10HAAs in beef jerky and determined the concentration in8kinds beef jerky selected from all over the country; to investigate the effects of main processing methods, including braising, oven-grilling, deep-frying and microwave cooking, on the formation of HAAs in beef jerky; and to find the control measures of HAAs formed in beef jerky. The main contents and results of this study were as follow:1. Study on determination of10HAAs in beef jerky by high performance liquid chromatographyBeef jerky was used as research subject. Sample pretreatment conditions and chromatographic analysis conditions were optimized for the method which could determine10HAAs in beef jerky by solid-phase extraction-high performance liquid chromatography (SPE-HPLC) simultaneously. HAAs were eluted from Extrelut with60mL dichlormethane (containing5%toluene), and then the extract was purified with propylsulfonic acid silica (PRS) columns and C18SPE columns, HAAs were stored in methanol-ammonia solution in the end. Separation of10HAAs was achieved by using TSK-gel ODS-80TM column and a gradient elution procedure with the mobile phases of acetonitrile and0.05mol/L acetic acid-ammonium acetate buffers (pH3.5). Identification and quantitative analysis of HAAs fraction was carried out using a HPLC system with ultraviolet-fluorescence detector. Results showed that the correlation coefficient of10HAAs were all above0.999and the limit of detection were in the range from0.02to2.46ng/g. Recoveries of10HAAs spiked in beef samples were61.69%to101.81%with the relative standard deviation (RSD) between0.28%and7.81%. This method is with wide linear range and high sensitivity, which can be successfully applied to the analysis of HAAs in actual meat samples. The HAAs content of8beef jerky was analyzed with this optimized method, the study found that Harman and Norharman were detected in all beef jerky samples, and the total HAAs content of beef jerky was between16.5ng/g and60.38ng/g.2. Study on effects of processing methods on HAAs formation in beef jerkyBraising, oven-grilling, deep-frying, and microwave cooking are the main processing methods of beef jerky. In this experiment, beef semitendinosus was used as test material, and effects of different braising time, oven-grilling temperature and time, deep-frying time, and microwave cooking time on the formation of HAAs in beef samples were studied. Results showed that different HAAs types and contents were detected in beef samples processed by different methods. Only Norharman and Harman were detected in braised beef samples, in which the types and contents of HAAs were the least with the total HAAs amount of0.18-0.19ng/g. The low HAAs contents0.51-0.61ng/g were also found in microwave cooked beef samples, in which four HAAs were detected, namely Norharman. Harman. Trp-P-2and PhIP. The total HAAs amount of0.28-4.10ng/g was found in deep-fried beef samples, and IQ was found in the beef sample deep-fried for60s. Temperature and time are two important factors affected HAAs formation, it was found that the HAAs concentration increased significantly with increasing oven-grilling temperature and time (p<0.05), the highest HAAs concentration as well as the most HAAs types (including4,8-DiMeIQx, Norharman, Harman, PhIP and AaC) were found in oven-grilled beef sample at180℃, in which25.24ng/g HAAs was found, while0.11ng/g HAAs was found in oven-grilled beef sample at60℃. It was also found that Norharman and Harman were all detected in different processed samples, while MeIQx, Trp-P-1, and MeAaC was not detected in any processed sample.3. Study on control measures of HAAs formation in beef jerkyBeef semitendinosus was used as test material. Effects of8different spices on the formation of HAAs in beef, which dipped in1%spice, were studied. Besides, inhibitory effects of different galangal addition, dipping time, and flavonoids on HAAs formation were further studied. Results showed that the different HAAs types and contents were detected in beef samples after dipping processed with different spices. Both in pepper dipped sample and in angelica dipped sample were detected the higher HAAs amount, and the most HAAs type was found in pepper treatment group. The inhibition on HAAs was unstable in beef samples dipped in anise, clove, or tangerine solution. The lower HAAs concentration was found in galangal dipped sample and cinnamon dipped sample than blank samples, however the amount of PhIP or AaC was increased after cinnamon dipped. It was found that galangal dipping was likely to reduce the formation of Norharman, PhIP, and AaC significantly, inhibition rates were4.92%～37.70%,26.32%～66.67%, and33.33%～66.67%, respectively. Moreover, influences of spices on HAAs formation in beef samples were related to the processed methods, the HAAs content detected at200℃was higher than that at100℃. Besides, galangin, quercetin, and kaempferol could inhibit the formation of Norharman and Harman in beef significantly, while study in the model system was also showed that galangin and quercetin had an obvious inhibition influence on HAAs formation. |
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