Improving preservative effect of pork ham sausages by irradiation

Abstract: Irradiation is a kind of effective food sterilization technology, which can effectively inhibit and eliminate the pathogenic or spoilage microorganisms. Meat and meat products, due to their high level of nutrients, pH value (5.5-7.0) and high water activity, offer a congenial environment for the growth of bacteria. In recent years, the utilization of irradiation in ready to eat (RTE) meat products is gradually getting people's attention, because many of the ready-to-eat cooked meat products are sterilized by high temperature above 100 ℃, which may could cause the nutrition loss and flavor deterioration. Pork ham sausage is a kind of important cooked meat product, which has won good graces of many peoples. Thus, this study mainly used the γ-irradiation for pork ham sausages preservation to investigate the effect of different irradiation doses on the preservative effect of pork ham sausage, and finally chose a suitable irradiation dose for pork ham sausages. The study mainly irradiated the pork ham sausage using the γ ray of 60Co at 1, 3, 5, 7 or 9 kGy, respectively. After irradiation, the pork ham sausages were stored immediately at 4 ℃ for 4 weeks, and the changes of lipid oxidation (TBARs), protein oxidation (carbonyl value), color, pH value, TVB-N content and total microbial counts were measured during the storage. Through analyzing these indices, the effect of different irradiation doses on pork ham sausage was discussed, and a suitable irradiation dose for the pork ham sausage was chosen. The results showed that irradiation could effectively decrease the oxidative stability of the lipid and protein of pork ham sausage, which consequently promote the lipid and protein oxidation of the pork ham sausage during storage at 4 ℃, and the effect was enhanced with irradiation dose increase. Due to the influence of irradiation on lipid and protein oxidation, the color of the samples was also affected by irradiation. But 1 kGy irradiation had no a significant effect on the color of pork ham sausage. 3 to 9 kGy irradiation could significantly decreased the a* value and increased the L* value compared to the control sample (P<0.05), and both of them decreased gradually with storage time increasing. The decrease rate of high dose irradiation groups was faster than that of low dose irradiation groups. The pH value of samples was not significantly affected by the irradiation dose (P>0.05) and also not changed significantly during the cold storage, which just changed within the range of 6.0-6.5. For all samples, the TVB-N content increased with storage time increase. But for irradiated samples, the increase rate was significantly lower than that of the control sample. And when the irradiation dose increased to 5 kGy, the inhibitory effect of irradiation on the TVB-N formation was not changed significantly with the continually increase of the irradiation dose. This result was very consistent with the microbiological analysis result. These results suggests that 5 kGy irradiation can play an effective inhibitory effect on the microorganisms of pork ham sausages, and will be a very promising ham sausage preservation technology.