Effect of Irradiation on Shelflife and Microbial Quality of Cold-Stored Sous-Vide Mackerel Fillets

Abstract

The combined effect of irradiation on microbial quality and shelflife of sous-vide mackerel fillets was investigated. Fillets were vacuum packaged, pasteurized (70C, 10 min) and rapidly cooled. Sous-vide fillets were separated into three groups as nonirradiated (control) and irradiated at the doses of 2.5 and 5.0 kGy, respectively. Samples were stored at 2 ± 1C. Sensorial, physical, chemical and microbial analyses were carried out weekly. According to the sensory results, 5.0 kGy irradiated samples were acceptable until the eighth week of cold storage while control and 2.5 kGy irradiated samples were unacceptable by the seventh week. Total mesophilic and psychrophilic bacterial counts and TVB-N values of control samples exceeded the limits on the sixth week; however, irradiated samples never exceeded the limits. Irradiation of sous-vide fillets provides microbial safety and longer shelflife to consumers who prefer both safe and quick food. Practical Applications Ready-to-eat foods are preferred by most of the consumers having not enough time to spend for cooking. Sous-vide technique, which is also popular in ready-to-eat foods, is generally a low temperature-short time process protecting texture, juiciness and flavor of fish. However to reduce or eliminate the risk linked to the possibility of inadequate pasteurization of sous-vide cooking, an additional hurdle like irradiation would be useful. In the present study microbial limits were exceeded while sensory scores were still acceptable for non-irradiated group which may mislead the consumers preferring sous-vide fish and cause food poisoning. Sous-vide cooking combined with irradiation technology enhances microbial quality, provides food safety and increases the shelflife of sous-vide fillets.