Scallops have traditionally been blast or sharp frozen. This study compared the quality of at-sea cryogenically frozen scallops with fresh and mechanically frozen scallops. A liquid CO₂ batch freezer was installed on-board the scallop boat. Samples were analyzed for microbiological, physical, chemical and sensory qualities. Sample types included fresh scallops, mechanically frozen scallops and 4 hr and 24 hr (on ice) cryogenically frozen scallops. The thaw loss mean of 4 hr cryogenically frozen scallops was 2.41 percent compared to means of 4.21 percent for 24 hr (on ice) cryogenically frozen scallops and mechanically frozen scallops, P < 0.0001. Cook loss for the 4 hr cryogenic frozen scallop was also reduced (P < 0.01) by 27 percent when baked. Cook method did not affect cook loss. Color measurements on the CIE L* a* b* scale did not differ significantly for raw or baked scallops. Instron peak force measurements had a very high standard error and therefore were not be analyzed statistically. The 4 hr cryogenically frozen scallops met the French Moisture/Protein ratio test standard of 5 (P > 0.02) but higher ratios were observed for 24 hr (on ice) cryogenically frozen scallops and mechanically frozen scallops. Scallops meeting this standard have greater export potential and the ability to attract high value markets. Variations observed in proximate composition were minor and may be due to biological factors. Sensory panelists found a significant difference (P < 0.01 to P < 0.05) among the randomly presented pairs of scallops. Over a 5 month storage period, the sensory characteristics of odor and taste of the cryogenically frozen scallops diminished and the mechanically frozen scallops were consistently scored higher. Mechanically frozen scallops had significantly lower cfu/gm for aerobic, psychrotrophic and coliform counts compared to fresh and cryogenically frozen scallops. The 4 hr cryogenically frozen scallop had lower thaw and cook loss which could have a significant economic and nutritional significance. Mechanically frozen scallops had a lower microbiological population and frozen storage for 8 months did not affect its taste or odor. Improved Sanitation and process control could establish cryogenically frozen scallops as a premium product. / Master of Science

Three different species of fish (sea trout, Spanish mackerel and catfish) were studied. Samples undergoing normal spoilage were compared with samples which had undergone a sanitizing treatment with alcohol. Differential temperature storage studies were conducted at 290 °F (-1.7 °C) and 32 °F (0 °C). Fish quality was assessed by means of microbiological, chemical and sensory analyses. Quality assessment via measurement of proteolytic and lipolytic enzymes was attempted, but these enzyme activities were not detected in any of the samples. It was not possible to differentiate between the contributions of microbial and autolytic spoilage. Alcohol treated samples (reduced numbers of microorganisms) had shelf-lives extended by 6-10 days over untreated samples. The shelf-life of samples stored at 290 °F was extended by 6-10 days over the shelf-life of samples stored at 32 °F. Treated samples stored at 290 °F received highest sensory scores and untreated samples stored at 320 °F received the lowest scores. It was seen that the three fish species studied had different shelf-lives: sea trout-6 days, Spanish mackerel - 10 days and catfish - 16 days. Decomposition rates differed significantly between species and this factor must be taken into account when marketing strategies are developed by firms engaged in fresh fish sales. / Master of Science