Improving the Microbial Safety of Ice Cream by Gamma Irradiation

In this study, a survey for the microbiological status of 120 ice cream samples revealed the presence of high microbial counts and different pathogenic bacteria in different samples. Therefore, the possibility of improving the microbial safety of different ice cream samples through irradiation treatment was studied. Ice cream samples were gamma irradiated in the frozen state at doses of 0, 1, 2, 3 and 4 kGy and examined for their microbiological and sensory properties during frozen storage. The results showed that irradiation treatments significantly reduced the counts of microbial populations, while En- terobacteriaceae were completely inactivated in samples irradiated at 2 kGy dose. Furthermore, irradiation dose of 3 kGy completely inactivated the inoculated Staphylococcus aureus, Listeria monocytogenes and Salmonella typhimurium, while significantly reduced the counts of Bacillus cereus spores in samples. Meanwhile, frozen storage had no significant effect on inoculated pathogens. Ice cream samples that irradiated at 3 kGy dose were acceptable for their sensory attributes during storage. Therefore, gamma irradiation can be applied at dose of 3 kGy to improve the microbial safety of frozen ice cream products without adverse effects on their sensory acceptability.