Date of Award

1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

J. Samuel Godber

Abstract

The lipid composition, and changes to lipid components of several marine finfish due to frozen storage, canning and use of various physical and chemical treatments during storage were evaluated. In Phase I, and lipid content of mullet (Mugil cephalus), croaker (Micropogon undulatus), redfish (Sciaenops ocllata) and red snapper (Lutiganus campechanus) fillets obtained from a local supermarket, was approximately 5% with phospholipids representing $<$5% of the total lipid. Vitamin A was not detectable but vitamin E was found in mullet. Mullet had a higher degree of oxidation compared to other species. In Phase II, fresh mullet were wrapped in oxygen impermeable freezer paper or vacuum packaged and frozen at $-$20$\sp\circ$C, or were thermally processed. After 90 days of frozen storage, a second batch of mullet was thermally processed. Total lipid, phospholipid, vitamins A and E and oxidation were determined at 0, 90, 180 and 360 days of storage. TBA number increased by 9.42mg/1000 g after 360 days of frozen storage. Oxidation did not occur in canned fish. Fish canned at 90 days evidenced greater oxidation after canning but further oxidation during storage did not occur. Vacuum packaging inhibited oxidation to a significant degree. Phospholipid decreased in frozen fish to the greatest degree, followed by vacuum packaged samples. Loss of phospholipid in freshly canned mullet was small. In frozen canned mullet, the change was greater. Vitamin E level decreased during frozen storage from 0.69 mg/100 g to a trace amount and the loss was 38% as a result of canning. In Phase III a comparative effect of prefreezing dip treatment, use of antioxidants in the dip and oxygen limitation by vacuum packaging on the lipid composition of frozen stored blackdrum (Pogonius cromis) was studied. Analyses were made at 2 week interval during a 12 week storage period. Total lipid averaged 4% in all treatment samples and phospholipid was $<$5% of total lipids. The effectivness for the inhibition of oxidation in frozen blackdrum was 0.025% TBHQ (tert-butylhydroquinone) $>$ 1% and 0.5% $\alpha$-tocopherol $>$ water dip $>$ vacuum pack $>$ no dip treatment. Vitamin A was quantifiable but not Vitamin E. No significant change in Vitamin A content was observed in any treatment group.

Pages

169

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