Date of Award

1998

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

J. Samuel Godber

Abstract

This farm-raised catfish quality study measured desirable flavor attributes, Chickeny, Nutty, Fat Complex, Corn, Sweet, with the objective to determine effects of feed ingredients, time-on-diet and genetic strain. Overall flavor impact differences were tested by triangle tests. The diets were Casein-base reference feed by itself or partially substituted with: 10% catfish meal, 10% meat and bone meal, 10% rice bran, or 3% menhaden oil and commercial feed formulation. Fish were grown indoors to minimize environmental flavors for 70, 160, 210 and 318 days. The genetic strains evaluated were channel, albino channel, blue, hybrid channel x blue, and black bullhead catfish. These fish were stocked and fed commercial fingerling feed for no less than 14 days. Blended individual fish samples were prepared for trained descriptive (n = 9) and triangle test panels (n = 18). The descriptive analyses showed no significant differences due to feed, time on-diet, or genetic strain. Differences found were not greater than the minimum detectable differences set by a preliminary power analysis. Triangle tests revealed black bullheads to be different from all other genetic strains, as was expected. Commercial reference catfish were found to be different possibly because of a slight off-flavor that was a cue to panelists. Inconsistent overall impact in descriptive and triangle evaluations indicates small differences exist that would likely be at the same intensity or masked by common flavors from pond influences. Fillet fat content was consistent with other reports, and the lack of flavor differences with increasing time-on-diet suggested that longer growing time to develop flavor is not warranted. This study supports producer practices of least-cost formulation. Odor analysis by gas chromatography-olfactometry was performed on selected treatments to explore patterns of impact odorants from catfish oil extracts. An intensity method was performed by four panelists. Twenty compounds were found that met the criteria that at least one panelist rated a moderate intensity or higher. All compounds have been found in animal and vegetative products. The three most consistent stimuli perceived were green grassy, mushroom and mothballs. Canonical correlation of the reliability of odor compound data to predict flavor-by-mouth characteristics did not find any significant relationships.

ISBN

9780599213814

Pages

122

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