51A-31

F. R. ANTOINE¹, C. I. Wei², W. S. Otwell, C. A. Sims, A. D. Hogle, R. C. Littell⁶, and M. R. Marshall. (1) Department of Food Science and Human Nutrition, University of Florida, Building 685, SW 23rd Drive, PO Box 110720, Gainesville, FL 32611, (2) Nutrition and Food Science, Auburn University, 328 Spidle Hall, Auburn, AL 36849-5605, (3) Statistics Department, University of Florida, 526 McCarty Building C, Gainesville, FL 32611

JUSTIFICATION Fish quality assessment is important to regulators, purveyors and consumers. Many chemical, physical, and microbiological methods are used for the determination of fish quality. However, there is no one objective criteria which is universal, and new and accurate methods are constantly being sought. Total volatile base-nitrogen (TVB-N), sensory and aerobic plate count (APC), and Aroma Scan are a few of the various criteria used for measurement of fish quality.

OBJECTIVE Our objective was to assess the relationship of sensory evaluation and APC with TVB-N because these three parameters are widely used for assessment of fish quality, and to determine the effectiveness of Aroma Scan as a new tool for mahi-mahi quality assessment.

METHOD Two groups of fish, each consisting of six mahi-mahi fillets, were refrigerated at 7°C, the temperature of most domestic refrigerators. Samples were taken from each group on days 0, 2, 4, 6, 8 and 10. All microbial samples were analyzed immediately after sampling, using a standard microbial protocol for APC. TVB-N was measured using the direct MgO steam distillation procedure.

RESULTS Results showed that TVB-N reached unacceptable levels after day 3, the time at which the APC reached 106 cfu/g. On a scale of 1-10, where 10 was very fresh and 1 very spoiled, sensory odor scores reached 6 by day 3. There was a 0.98 power correlation of TVB-N with the sensory odor, 0.94 linear correlation of odor with APC, and 0.8 logarithmic correlation of APC with TVB-N. Aroma scans showed distinct trends for deteriorating fish quality.

SIGNIFICANCE The results show that TVB-N is a good index of mahi-mahi quality.