Study On Changes And Control Methods For Color And Flavor Of Fujian Flavor Duck During Storage

Fujian flavor duck, as a kind of Chinese traditional sauced meat products, is favored byChinese customers. High temperature sterilization together with vacuum packing technologycan expand the market of sauced products, however, they may lead to the degradation of itscolor and flavor during storage, which will have negetative effects on consumer’s choose.Regarding to the above problem, we have anlayzed the changes of color and flavor of Fujianflavor duck during storage, and explored the methods for inhibiting and slowing downdegradation by controlling the hurdle factors, so as to provide basis for industrial productionof Fujian flavor duck with high quality and long shelf life.The typical flavor and odor-active compounds of Fujian flavor duck detected byheadspace solid phase microextraction (HS-SPME) combined with GC-MS and GC-Otechniques were studied first. The GC-MS results showed that aldehydes derived from proteinand lipid oxidation formed duck meat flavor of Fujian flavor duck and terpenes formedtypical Zingiber flavor. Other volatiles such as esters, alcohols, ketones, acids, hydrocarbonsmade contributions to final flavor of Fujian flavor duck product. The GC-O results showedthat high temperature sterilization resulted in the increasing of aldehydes and the decreasingof terpenes. Zingiber flavor and duck meat flavor were reduced and masked by warmed-overflavor (WOF).For different processing methods, soy sauce contributed mainly to product’s color, whileroasting affected the flavor through maillard reaction. Adding soy sauce and roasting inhibitedoxidation reaction to some extent, but the inhibition was not obvious during storage. Theresults of storage research indicated that high temperature and light accelerated oxidation ofprotein and lipid and degradation of pigments and terpenes. Degradation of product color andflavour were obvious and showed close relation. The color of products turned into red whenstored at50oC, while turned into grey when stored at room temperature, and changed muchsignificantly with light. Aldehydes and ketones were formed by oxidation of unsaturated fattyacid and the relative contents were increased during storage. As a result, duck meat flavorwere reduced and masked by WOF.To improve the reduction of product color and flavor caused by high temperaturesterilization and storage stability, different irradiation doses were applied to sterilize.Compared with control samples,8kGy irradiated samples had unpleasant red color and andincreased with higher doses. Kinds and content of volatiles were different between hightemperature sterilization Fujian flavor duck and irradiation products. Irradiation producedmuch more hydrocarbons, alcohols and esters. Content of aldehydes was lower while contentof hydrocarbons was higher in8kGy and15kGy products. This can be attributed to chagngesof product packaging after irradiation. Hydrocarbons of30kGy products changed a little butcontent of aldehydes was increasing significantly which was similar to that of hightemperature sterilization products stored after five weeks. High dose of irradiation can easilylead to protein and lipid oxidation, and WOF, which was not accepted by consumers. Thecolor of8kGy products stored at37oC and light-exposed turned into red and gray during storage. Content of aldehydes was increased while terpenes was decreased and all8kGyproducts were deteriorated after stored for8weeks. This indicated that irradiation sterilizationcan not effectively inhibit changes of color and flavor during storage.On the basis of above results, we studied the feasibility of reducing the heating intensityof vacuum packing Fujian flavor duck by cotrolling hurdle fators. Gradient expriments ofdifferent conditions of pasteurization and addition amounts of natural preservatives wereconducted. The results showed that0.3g/kg Nisin,3g/kg chitosan and3g/kg protamine werethe most appropriate amout.90oC for30min pasteurization combined with110oC for15minwere the best sterilization condition. After storage experiment, we got long shelf life productsand the methods using hurdle factors could inhbit changes of color and flavor of Fujian flavorduck during stoage.