Effect of delayed icing on the storage life of rainbow trout

Rainbow trout ( Salmo irideus ), were divided into groups: (1) iced immediately, or (2) kept at 10 °C for 6 hr, (3) 20 °C for 6 hr, (4) 20 °C for 18 hr, (5) 30 °C for 4 hr, (6) 30 °C for 6 hr. Fish in groups 2–6 were iced at the end of the stipulated temperature/time period of holding. Quality was subsequently assessed every 2 days for 14 days during iced storage: sensory assessment using criteria of appearance, texture and odour; chemical assessments by measurement of total volatile bases, hypoxanthine and thiobarbituric acid: microbiological assessments by total bacterial counts at 20 °C/72 hr and 37 °C/48 hr incubation. The results indicate that deamination due to bacterial action and hydrolysis of fats increases progressively with rising temperature prolonged periods of storage prior to icing, and results in final spoilage. Fish iced immediately after delivery and those iced after being kept at 10 °C for 6 hr were acceptable to quality even after 14 days of iced storage. Recommendations are made for maintenance of quality and extension of shelf life.