Effects of Formaldehyde on Salt Extractable Proteins of Gadoid Muscle

Abstract

Addition of formaldehyde to fresh cod muscle, to give concentrations of 10 to 200 ppm, brought about marked decreases in the extractable protein content during holding periods of 24 hr or less at 0 C. Similar levels of formaldehyde, produced during frozen storage of gadoid (Atlantic cod, Gadus morhua, pollock, Pollachius virens, cusk, Brosme brosme, and silver hake, Merluccius bilinearis), fillets at −5 C, brought about similar reductions in the extractable proteins. Comparative tests showed that, in the concentrations normally encountered in deteriorating frozen gadoid fillets, formaldehyde was a much more active protein-insolubilizing agent than free fatty acid. It is evident that in these protein changes more than one mechanism is involved. Observed species-differences in the extent to which fish proteins became insolubilized during storage appeared to be related to presence or absence of these different mechanisms. The more rapid and more extensive denaturation of most gadoid fillets in frozen storage than of fillets of nongadoid species appears to be directly related to the presence of muscle enzyme of the former group that is capable of producing formaldehyde from trimethylamine oxide, which is absent in the muscle of the nongadoid species so far tested.

Effect of the addition of maltodextrins and sucrose on the ice-melting onset of minced fish muscle

“…The observed Tm' is close to that temperature below which TMAO-ase has been reported to become inactive. 21,22 This would seem to indicate the technological importance of Tm' for the stability of frozen ®sh.…”

Behaviour of the mechanically separated flesh of some common fish species of the Mexican shrimp by‐catch during storage at −20°C

“…The formation of these compounds in the fish flesh has been shown to be related to a loss of extractability of the muscle protein (Castell, 1971;Castell, Smith & Dyer, 1973). It is thought that complexing of the F A with proteins is the major causative factor of protein aggregation in gadoid species, such as Alaska pollock and red hake (Dyer, 1973). Decreases in protein extractability in fish muscle are associated with increased toughness when cooked and a consequent decline in product acceptability.…”

Factors that accelerate dimethylamine formation in dark muscle of three gadoid species during frozen storage

“…The meat of gadoid species such as Alaska pollock, cod and hake has poor stability when frozen because of the degradation of trimethylamine-N-oxide (TMAO) to yield equimolar dimethylamine (DMA) and formaldehyde (FA) [1][2][3]:…”