Date of Award

1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

J. Samuel Godber

Abstract

The effects of cooking temperature, refrigerated storage, and the presence of sodium tripolyphosphate (STP) and soy protein isolate (SPI) on the development of warmed-over flavor (WOF) in restructured beef roasts were studied. In Phase 1, restructured beef roasts were cooked in a water bath at temperatures of 70, 85 and 100$\sp\circ$C. In Phase 2, four types of roasts containing all combinations of STP and SPI were cooked in a water bath at 70 and 100$\sp\circ$C. The cooked roasts in both phases were then stored at 4$\sp\circ$C for 0 and 3 days. Higher cooking temperatures and longer storage periods tended to increase oxidation as measured by thiobarbituric acid (TBA) analysis. Sensory panelists detected differences in WOF due to storage but not cooking temperature. Significant interactions between cooking temperature and storage indicated that oxidation proceeded more rapidly at higher cooking temperatures. Correlations between TBA values and total lipids, phospholipids, and nonheme iron indicate that these factors may contribute to lipid oxidation. Both STP and SPI inhibited oxidation, STP being more effective at higher cooking temperatures while SPI at lower cooking temperatures. Their effect was not detected sensorially. The antioxidants also may have a synergistic effect in inhibiting oxidation. In addition, their antioxidative effects may be concentration dependent. Lower cooking temperatures resulted in higher cook yields. Moisture content, expressible moisture, and water-binding were also considerably greater at lower cooking temperatures, while Instron shear force values and sensory scores tended to be higher but not significant. Dehydration of the roasts occurred during storage accompanied by an increase in water-binding and in Instron shear force values. Sensory panelists rated the stored roasts less juicy and less tender than roasts that were not stored. Incorporation of STP and SPI resulted in higher, though nonsignificant, cook yields. In the presence of STP, the total moisture of the cooked product was significantly greater than when STP was omitted. No differences in juiciness and tenderness were detected by the sensory panelists due to STP and SPI. This study indicates that flavor and textural stability can be improved by incorporating antioxidants, cooking at lower temperatures, and minimizing refrigerated storage.

Pages

266

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