Effect of gamma irradiation on the shelf-life of vacuum-packaged silver carp surimi in 4 °C

The current study investigates the effect of gamma radiation (0, 1, 3, 5, 7 kGy) and vacuum packaging on shelf-life of silver carp surimi stored at 4 oC based on variations in pH, peroxide value (PV), thiobarbituric acid (TBA), total volatile nitrogen bases (TVB-N), free fatty acids (FFA), colorimetric parameters (L*, a*, b*), total viable bacterial count (TVC) and textural profile analysis during 15 days. The results indicated that pH did not change with gamma radiation (P> 0.05). Results of oxidative index showed that PV and TBA in surimi reduced significantly with an increase in gamma radiation (P< 0.05) while their increased by increasing the storage time. Irradiation and the storage time significantly increased TVB-N content (P< 0.05). The increase the radiation dose (up to 7 kGy) and the storage time (up to 15 days) had a significant increasing effect on FFA in refrigerated surimi. Correspondence L. Roomiani, Department of Fisheries, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran (e-mail: l.roomiani@yahoo.com). Colorimetric evaluations demonstrated that after irradiation, samples had generally higher L*, a*, b* indices. Furthermore, increasing the radiation dose significantly reduced the total bacterial count in surimi samples (P< 0.05), but this parameter exhibited a significant increase (P< 0.05) with increasing storage time. Based on the textural profile analysis it was found that increasing radiation dose and storage time reduced the hardness and chewing ability indices. According to the microbiological and chemical results, the optimal storage time for surimi, compare to the control (0 kGy) treatment, was measured for 7 kGy treatment which could increase the storage time by 3 days compared to the control.