Date of Award

5-2006

Level of Access

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Food and Nutrition Sciences

Advisor

Alfred Bushway

Second Committee Member

Rodney Bushway

Third Committee Member

Mary Ellen Camire

Abstract

The limited supply of fish meal has led to increased research on various alternate proteins for their suitability as a substitute to fish meal, which is the traditional protein source in aquaculture diets. Low cost, consistent availability, and excellent nutritional profile make soy an excellent candidate as an alternate protein. However, the off-flavors said to be associated with some chemical components of soy, such as the isoflavones, may limit its use in aquaculture. The main objectives of this research were to determine if dietary soybean meal or its components influenced the product quality of rainbow trout fillets and whether isoflavones were transferred from the diet into fish muscle. Another objective was to determine if the reduced lipid oxidation observed in the fillets of soy fed trout could be attributed to a specific soy component. Dietary genistein but not dietary soybean meal resulted in deposition of isoflavone into trout muscle. Neither dietary genistein nor dietary soybean meal had any adverse effects on fillet quality at the levels used in .this study. Fillets .from both genistein-fed rain bow trout and soybean meal-fed rain bow trout exhibited reduced lipid oxidation during refrigerated storage. Antioxidant studies of methanol and aqueous extracts from diets containing 40 percent soybean meal showed that such diets had higher free radical (DPPH*) scavenging capacity in comparison to similar extracts from soy isolate and soybean meal, but not the highest concentration of total phenols. The findings of this research may be of interest to soy farmers, aquaculturists, retailers, and consumers, all of whom are concerned with the production or consumption of a cost effective and high quality fillet product.

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