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Alaska pollock was headed, gutted, and frozen at sea in pre-and postrigor condition. Surimi made from this fish held at -29°C showed a gradual loss in gel-forming ability with time of storage. This loss in gel-forming ability was accompanied by a loss in viscosity and Ca+ +-ATPase activity of the surimi over the g-month storage period. The gel strength of kamaboko gels showed an inverse linear relationship with gel moisture over a limited moisture range. Simply freezing and thawing pollock resulted in surimi with significantly lower gel strength than that from fresh pollock.

Dimethylamine (DMA) forms very rapidly in heat-dried and freeze-dried fish muscle. The DMA forms regardless of species. The rate of DMA formation was related to the water activity (Aw) of the product with minimum amounts forming at Aw <1 and Aw 4. Evidence was developed to show that the formation of DMA in these products did not result from enzymic activity. In vitro studies show that several ionic constituents such as Fe2+, Sn2+, and SOz induce the degradation of trimethylamine oxide (TMAO) to DMA. Metal chelators such as EDTA and phytic acid in the presence of Fe2+ and Sn2+ rapidly accelerate the formation of DMA.Until a few years ago, only passing attention was paid to the formation of dimethylamine (DMA) in fishery products. It was well known, for example, that when fresh fish spoils, it is trimethylamine (TMA) that forms and not DMA. The presence of DMA in fish flesh was deemed somewhat of a nuisance because when present in significant quantities, it interfered with the analysis of TMA (Tozawa et d., 1970). It was also fairly well recognized that DMA was rather species dependent, forming in significant quantities only in gadoid species such as hake, pollock, and cod, but not in other commercially important species. Later, food scientists began to show some concern because This article not subject to US.

The activities of cathepsins B, D, H and L were compared in crude muscle extracts from four species of fish: Pacific whiting (PW), (Merluccius productus); arrowtooth flounder (ATF), (Atheresthes stomias); Alaska pollock (AP), (Theragra chalcogramma); and Pacific cod (PC), (Gadus macrocephalus). Both PW and ATF are known to undergo softening during post‐mortem handling and cooking while AP and PC do not. Cathepsin B and L activities were both higher in extracts of PW and ATF than in AP and PC. Cathepsins B and L activities were both much higher in PW than in ATF. Cathepsin H activity was highest in AP followed by ATF with PC and PW having the lowest activities. Cathepsin D activity was extremely low in all four species. The heat stability of the various cathepsin activities showed cathepsin B to be the most heat labile and was inactivated by 50C heating for 15 min. Cathepsin H activity was inactivated at 60C, while cathepsin L required 70C for inactivation. Cathepsins B and L are the most likely responsible for softening in PW and ATF during holding and subsequent processing. However, during cooking, cathepsin L likely causes the most damage since it requires 70C for inactivation. The difference in heat stability of cathepsins B and L can be used to differentiate between their activities.

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