The spoilage pattern of thawed yellowfin tuna carcasses was examined. After five days storage at 10" and 18"C, bacterial counts were low (

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The usefulness of ascorbic acid and chelating agents in retarding sensory deterioration and progression of oxidative rancidity in frozencooked mussels was investigated. Ascorbic acid with and without chelating agents proved effective in arresting progression of oxidative rancidity, in samples held at -12°C for 20 wk. However, these agents proved ineffective in preventing sensory deterioration of mussel meats under the same conditions. Mussels held at -30°C showed an improved sensory stability throughout the study and demonstrated less progression of lipid oxidation compared with mussels held at -12°C. Sensory deterioration at -12'C storage is associated in part, with lipid oxidative changes. The ineffectiveness of antioxidant agents in preventing sensory deteriorative changes may indicate the presence of other, as yet undetermined, degradative pathways.

An active lipid peroxidizing enzyme system was investigated in microsomal fractions isolated from the gonad and hepatopancreatic tissue of live cultivated mussels. Enzyme-mediated lipid peroxidation was detected in gonad microsomes and was shown to be dependent upon the presence of NADH, ADP, and Fe3 + ions. A marked increase in the peroxidizing capacity of gonadal microsomes was observed following lipid emulsion loading. Fresh microsomes prepared from hepatopancreatic tissue showed no detectable levels of lipid peroxidizing activity. However, freeze-thaw treatment of microsomes from both gonadal and hepatopancreatic tissues resulted in an initiation of activity in the hepatopancreatic tissue and increased the existing activity of the gonad microsomes.