Physico-chemical changes occurring in fish flesh during freezing and thawing as measured dilatometrically

The thesis deals with the use of a dilatometer in studying some of the physico-chemical phenomena occurring in fresh fish flesh when subjected to freezing at temperatures ranging from 0° C to -30° C. Two different kinds of fish flesh, marine lingcod (Ophiodon elongatus) and fresh water rainbow trout (Salmo gairdnerii) were used for comparison. True freezing point determinations of samples of fresh flesh cut from the above species of fish were made and found to be the same, viz, -1.5°C (29.1°F.). The percentage of water removed as ice at varying temperatures below the initial freezing point were calculated by necessary adjustments of experimentally determined values. A permanent net decrease in volume accompanying freezing and thawing of the samples of flesh was observed and measured. This change in volume is probably due to the denaturation of the protine, and was found to be 0.075%. The coefficient of cubical expansion (∝) of anhydrous fish muscle was measured for the first time and found to have the average value of 0.000118 over a temperature range from -30°C. to +20°C.Science, Faculty ofZoology, Department ofGraduat