The Effect Of The E-beam Irradiation And Microwave Heating On The Shelf Life, Volatile And Fatty Acid Of Surimi

Grass carp(Ctenopharyngodon idellus) is one of the most economically important species of cultured fish. Fish surimi is high-protein and low-fat food that has a unique texture and taste. It is also a value-added food produced from low-cost fish. The consumer preference for minimally-processed and additive-free foods has triggered the development of novel processing and preservation methods, i.e., E-beam irradiation.E-beam is a non-thermal physical technology that inactivates microorganisms and enzymes by radiation. The advantages of E-beam include no chemical residues and short processing times. Additionally, E-beam irradiation uses electricity, as opposed to radioisotopes (60Co or 137Cs) to generate ionizing energy. Therefore, E-beam is a controllable food processing application. This study focuses on The effect of the E-beam irradiation on the shelf life of grass carp surimi and microwave heating on the volatile and fatty acid of irradiated surimi.The effects of 10 MeV E-beam (0,1,3,5, and 7 kGy) irradiation and vacuum packaging on extending the shelf-life of grass carp surimi stored at 4℃ were evaluated basing on the total viable counts (TVC), physiochemical 2-thiobarbituric acid reactive substance (TBARS), total base nitrogen (TVB-N), biogenic amines (BAs), texture (TPA), color and sensory changes in surimi samples. In this study, we also evaluated the effects of e-beam irradiation and irradiation coupled to microwave heating (e-I-MC) on the fatty acid composition and volatile compound profile of grass carp surimi.The results are as follow:(1)Comparing to the control samples, the TVC, TVB-N content in surimi were significantly (p< 0.05) decreased by irradiation with different doses. Irradiation significantly (p< 0.05) inhibited the increase of PUT, CAD, HIM, and TYM contents during storage. However these parameters were significantly (p< 0.05) increased with storage time.(2)After irradiation, the samples generally had higher lightness and lower a* and b* values and lower hardness and chewiness significantly (p< 0.05). Based on the sensory analysis, unfavorable’metal odor’or’irradiated odor’was observed in surimi irradiated at 5 and 7 kGy.(3)Compared to control samples, e-beam irradiation generated three novel volatile compounds (heptane,2,6-dimethyl-nonane, and dimethyl disulfide) and increased the relative proportions of alcohols, aldehydes, and ketones. Meanwhile, e-I-MC significantly increased aldehyde levels and generated five heterocyclic compounds along with these three novel compounds. No significant differences in volatile compounds were detected in e-I-MC samples with increasing irradiation dose.(4)E-beam irradiation at 5 and 7 kGy increased the levels of saturated fatty acids (SFAs) and decreased the levels of unsaturated fatty acids(USFAs) (p< 0.05), but did not affect trans fatty acid levels (p>0.05). Irradiation, which had no significant effects on Eicosapentaenoic acid (EPA), decreased Dihydroptychantol A (DHA) levels. In the e-I-MC group, SFA levels increased and polyunsaturated fatty acids (PUFA) levels decreased. Additionally, monounsaturated fatty acid (MUFA) levels were unaffected and trans fatty acid levels increased slightly following e-I-MC.(5)E-I-MC treatment significantly increased aldehyde levels and generated five novel heterocyclic compounds including two furan compounds. However, there were no significant differences in the volatile compound profile of e-I-MC samples with increasing irradiation dose. This result reveals that cooking may decrease the level of volatiles formed via irradiation and may potentially attenuate the formation of off-odors.