Effect of heating condition on protein quality of retort pouched fish meat.

Abstract

Effect of heat processing on fish meat in retort pouches has been examined in connection with its protein quality. Bigeye tuna and halibut meat were heat-processed at two different temperatures (115°C and 124°C) varying in F0 values from 8 to 32. At the F0 value of 8 or 21, non-specific degradation of peptide bonds in the fish meat proteins was observed by electrophoresis to occur more slightly at 124°C than at 115°C and their amino acid compositions were not signi-ficantly changed during the heat processing. Glucose, glucose-6-phosphate, available lysine and in vitro digestibility of the fish meat were also determined in order to reveal the changes of protein quality from the standpoint of amino-carbonyl reaction. Losses of glucose, glucose-6-phosphate and available lysine followed the first order reaction kinetics during the heat processing, but were smaller at 124°C than at 115°C when compared at equivalent F0 values. On the other hand, in vitro digestibility of the fish meat decreased only slightly in the course of heat processing. From these combined results, it was concluded that when compared at the equal lethality, the protein quality of heat-processed fish meat in retort pouches could be retained more effectively at 124°C than at 115°C and that at least no remarkable loss in protein quality was observed under the heat processing at 124°C with F0=8.