Doctoral Dissertations

Ying Zheng

Date of Award

12-1995

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Food Science and Technology

Major Professor

Sharon L. Melton

Committee Members

Marjorie P. Penfield, John R. Mount, John W. Philpot, Robert W. Mee

Abstract

In the first of two studies, levels of cholesterol (CHOL) and fatty acids (FA) in nonpolar and polar lipids in raw and broiled ground turkey, beefalo, and beef were measured. Cooking losses including drip and evaporation also were determined. In the second study, raw and cooked, crumbled ground turkey, pork and beef after 0, 2, and 4 days of storage at 5-6°C were analyzed for levels of CHOL, fat, moisture, FA, conjugated dienoic acid (DIEN), TBA-value, fluorescent oxidation products (FOP), and cholesterol oxidation products (COP). Each successive stage including cooking and storage of the meat represented an increasing lipid oxidation level. Total cooking loss from browning each meat in a 190.5°C skillet for 5 min followed by 2 min drain was determined also.

Ground turkey contained higher levels of CHOL and unsaturated FA and lower levels of saturated FA than ground beefalo or beef. Beefalo was similar to beef in CHOL level. Broiling meat patties concentrated CHOL and fat contents in all meats, but had no effect on the types of or individual FA.

In contrast with broiling, browning ground meats reduced fat content in cooked meats. The decreases in levels of C17:0 and C18:0 and increases in C15:1, C17:1, C20:3n6, C20:4n6, C22:4n6 and C22:5n3 in meat during browning indicated that a greater portion of saturated FA was lost with neutral lipids than polar lipids into the drip.

Levels of C15:1 and C20:4n6 decreased with increasing oxidation in all three meats. DIEN content increased with increasing oxidation in pork. TBA value increased at a decreasing rate with increased oxidation in all three meats, but failing to increase significantly from 2- to 4-clay storage in turkey and pork. One FOP increased in concentration almost linearly with increasing oxidation in ground pork and beef. Three COP were measured with 7-ketocholesterol being the most abundant. During increasing oxidation in the ground meats accumulation of all three COP in pork and beef and of one FOP in turkey and pork demonstrated a greater potential to assess lipid oxidation than the TBA test.

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