Frozen storage life of red hake fillet blocks was estimated b y sensory evaluation to be 150 weeks at -20" F, 71 weeks at -5" F, 25 weeks at +5" F, 7.5 weeks at +lo" F u n d 2.7 weeks at +20" F. Shelf life was limited b y the development of a tough, fibrous texture and the reaction proceeded a t a faster rate a t temperatures above +5" F. Dimethylamine content, formaldehyde content and shear force measurement correlated very well with sensory texture score and thus, these objective tests could be useful for predicting textural quality. For product stored at temperatures above -5" F there was good correlation between extractable protein nitrogen and sensory texture score, but this correlation decreased with lower storage tempratures. Trimethylamine oxide content and p H diminished during the early phase o f storage and then progressively increased during continued storage. Centrifuged drip as a n objective quality test did not appear to be sufficiently sensitive or reliable for assessing textural quality.

Freezing and holding cod muscle in the frozen state favored the association process that involves protein–free fatty acid (FFA) complex formation and begins during aging in ice. Changes in protein extractability, in ultracentrifugal patterns of protein extracted, and in phase contrast micrographs of inextractable muscle fragments were followed in muscle that had been aged in ice to produce various contents of FFA and then frozen and held at −29 C. After 11 months, these changes, which took place largely during the first week of storage, were comparable with those that occur when the FFA are formed during frozen storage. The results were consistent with a reaction rate that was greater at −29 C than at temperatures a few degrees above 0 C.

Irradiation of cod fillets with a maximum absorbed dose of 100 Krad extended iced storage life by about 9 days. Further extension of several days resulted when irradiation was combined concurrently with either 60% CO:! packaging atmosphere or sorbate additive. Packaging at low oxygen tension did not provide any additional benefit for irradiated fish. No important difference ln storaae life of treated fish was observed due to-one vs three day postmortem age. The 100 Krad treatment extended grade B quality market life as opposed to grade A (prime quality) market life, Certain physical/ chemical tests were evaluated for their efficacy in estimating spoilage. Concentrations of TMA, DMA, hypoxanthine, APC and pH at spoilage were comparable in control and air-irradiated samples, but were less in sorbate-irradiated fillets.

The addition of oxidizing or reducing agents to minced red hake showed that oxidizing agents reduced the rate of dimethylamine (DMA) and formaldehyde (FA) formation, while reducing agents accelerated their formation. To determine the effectiveness of different oxidizing agents, H202, NaOCl, and KBr03 were added at four levels to minced red hake. DMA, FA, and trimethylamine oxide values showed that 0.05,0.10, and 0.25% levels of H202 were most effective in slowing the reaction rate. Although Instron measurements did not show the oxidizing agents to improve the texture greatly, the sensory panel analysis found the 0.05, 0.10, and 0.25% levels of H202 to have a better texture than the control.Investigations into the utilization of red hake (Urophycis chuss) as a human food have centered around trimethylamine N-oxide demethylase (TMAO-ase), which is thought

Protein extractability decreased as free fatty acid (FFA) was produced in cod muscle aged in ice. The decrease was small compared with that occurring in frozen-stored muscle of similar FFA content. Prolonged extraction in neutral salt solution in the presence and absence of bovine serum albumin (BSA) showed that loss in protein extractability in muscle aged in ice was reversible through dissociation of inextractable material and that the presence of BSA, a FFA acceptor, favored greater dissociation. Ultracentrifugal patterns of protein extracted from ageing muscle showed increasing polydispersity. Phase contrast microscopy showed that the inextractable material contained muscle fragments consisting of bundles of myofibrils, some of full fiber width. These results indicate that in ageing muscle, interaction of contractile protein with FFA results in the formation of a cross-linking network within the muscle fiber causing resistance to fragmentation and to protein extractability, and that the observed smaller loss during ageing in ice is in part due to dissociation occurring during extraction. They suggest that in muscle aged in the frozen state, the reaction between contractile protein and FFA increases and the complexes formed are stabilized.