| China is one of the biggest country of food irradiation processing. The total irradiation food has been one third of the world's irradiation food. The safety of food irradiation has become a focus of attention with the increasing number of such food coming to table. As an important part of food safety inspection, identification of irradiated food helps ensure the security of food, standardize the development of food irradiation industry and reduce losses of agri-food imports and exports, which is of great significance. Most of the irradiated food which is either from animal or from plant contains fat. There are lots of types and tons of processing products of irradiated food containing fat, which has a big effect on food safte, export trade and market surveillance. Thus it is very important and of practical significance to study on identification of irradiated food containg fat by detecting the changes of hydrocarbons produced during irradiation.In this paper, chilled beef and peanut were chosen for experiments because of the high economic value of the two typical irradiation processing samples. The identification of irradiated chilled beef and peanut was established by studying on extraction, separation and GC method and analysis of the concentration change of six kinds of hydrocarbons in samples before and after irradiation. The factors which impacted the concentration of specific hydrocarbons were studied to provide theory on the determination model of the irradiation dose of food containing fat. The main content of this paper and results showed as follows:1. Based on the EU standard EN1784:2003, hydrocarbons in chilled beef and peanut were extracted by using tissue crushing method, separated by Florisil column and analyzed by GC-FID. Qualitative parapmeter-retention time and quantitative method-internal standard method were established. The precision of the instrument was investigated, with different concetrations (0.1 mg/L, 1mg/L and 10mg/L) of seven hydrocarbons 1-C14:1, C15:0, 1,7-C16:2, 1-C16:1, 8-C17:1, C17:0 and C20:0 (internal standard). 1,7-C16:2 and 8-C17:1 were determined as radialytic specific hydrocarbons.2. SPME was studied as a fast and simple sample preparation technology. HS-SPME-GC-MS was extablished by analysis of the specific hydrocarbons 1,7-C16:2 and 8-C17:1. SPME temperature, SPME time and desorption time were optimized. The final optimized conditions were 90℃, 60 min and 2 min. Based on the detection of hydrocarbon markers in irradiated food by HS-SPME-GC-MS method, irradiated food containing fat can be identified by qualitive determination of hydrocarbon markers 1,7-C16:2 and 8-C17:1. A standard of quick identification on irradiated food containing fat was developed, which provided scientific help for the establishment of standards about qualitive identification of irradiated food.3. The in-depth research of the major factors of dose, packaging condition and storage time on the impact of the concentrations of specific hydrocarbons 1,7-C16:2 and 8-C17:1 was carried out. The impact mechanism were studied. For chilled beef and peanut, the linear regression equations between the concentration of specific hydrocarbons and dose were built with the correlation coefficient R2 more than 0.99. The connic fits between loss rate and storage time were also built (R2>0.97). Thus, a method on how to cacultate the dose of irradiated food was developed based on these two curves, which was an theoretical exploration for establishing the determination model of the irradiation dose of food containing fat. |
