Effect of gamma irradiation against microbial spoilage of hummus preserved under refrigerated storage

The current study aimed to evaluate the preservation of hummus packed in laminated pouches to extend its shelf life for a period of 35 d using a combined treatment of gamma irradiation and refrigerated storage. The effects of different irradiation doses (0, 0.1, 1.5 and 2.5 kGy) and refrigeration (4 °C) against microbial spoilage were investigated. Microbial criteria of total mesophilic aerobic counts, lactic acid bacterial counts, and yeasts and molds decreased significantly (P ≤ 0.05) in a dose dependent manner. Furthermore, dose of 2.5 kGy decreased the lactic acid bacteria counts to undetectable levels for the first 10 d of storage. Although microbial load increased during 35 d of refrigerated storage, samples treated with doses of 1.5 and 2.5 kGy showed a good microbial quality that complies with microbial limits set by national and international authorities for ready to eat foods. Furthermore, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis and coliform bacteria were not detected in the irradiated samples as well as in the controls. It was observed that a dose ≥1.5 kGy combined with refrigerated storage at 4 °C could be used to extend the shelf life of hummus samples in laminated pouches up to 35 d.