Studies on the storage of iced mackerel (Scomber japonicus): quality changes during storage

Abstract

Samples of mackerel (Scomber japonicus), caught off the coast of Ghana, were iced alive and stored for 23 days. The quality during storage was assessed by sensory and objective methods. The spoilage of mackerel as determined by visual and olfactory assessment occurred in four phases. In phase one, incipient deterioration in quality occurred and all the fish were in rigor mortis. The fish passed out in rigor in phase two, and the iris changed from yellow to black. as the fish entered the phase three, the flesh began to soften, the skin started fading and wrinkling and a yellow slime appeared. In phase four, putrid odours were detected. The fish remained acceptable up to 19 days in ice. Various objective tests of quality were studied but only the overall freshness as measured by the Rank-Torry freshness meter and hypoxanthine showed potential for use as indices of quality. The pH value showed potential as a spoilage indicator