Date of Award

1981

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Raw and blanched whole-glazed crawfish, and crawfish tailmeat were frozen in plastic trays and polyethylene pouches respectively and stored for 10 months at -18 C. Samples were drawn at two-month intervals and analyzed for 2-thiobarbituric acid values, and free fatty acid content. In general, blanching, presence of fat, and air were found to accelerate the development of oxidative rancidity. On the other hand blanching was found to reduce but not totally inhibit the production of free fatty acids. Fat from whole-glazed samples was analyzed at the beginning and end of the storage period. Six lipid fractions were confirmed, and one fraction was tentatively identified, whereas another fraction which appeared to be the product of heat treatment remained unidentified. Long chain fatty acids were also identified, and crawfish lipid was found to contain a high proportion of polyunsaturated fatty acids. Frozen storage and heat treatment had different effects on the different lipid fractions and fatty acids. In another study frozen tailmeat in polyethylene bags were analyzed for protein solubility, pH, and texture at 2-month intervals. Storage time resulted in an overall decrease in the solubility of the water and salt-soluble proteins, while cooking and air packaging resulted in decreasing the solubility of the salt soluble fraction. Both cooking and storage time had a significant effect on the pH of the tissue and its texture score. Electrophoretic studies of the proteins revealed that heat treatment had the most effect on the slow moving fractions on SDS polyacrylamide gel. However, frozen storage had a more complex effect than that of heating.

Pages

136

Share

COinS