Pacific whiting and its by-products were good raw materials for high quality fish sauce production. Heat stable and salt activated enzymes were responsible for autolytic activity in Pacific whiting and by-products. According to temperature profiles of raw materials at various salt concentrations, two fermentation temperatures, 35°C and 50°C, were selected and compared at 25% salt under static atmospheric condition. Higher yields and faster production rate were obtained from samples incubated at 50°C. Therefore, the apparent optimum condition for fish sauce fermentation using Pacific whiting and its by-products was at 50°C with 25% salt under static atmospheric condition. All physicochemical characteristics, except color and browning color, reached the level of commercial fish sauce within 20 days. Nitrogen contents in all samples reached the level of commercial fish sauce (16.3 g-N/mL) within 112 days. Predominant microorganisms found during fermentation were Staphylococcus, Bacillus and Micrococcus. Alpha-amino acid content appeared to be identified as a good parameter to estimate total nitrogen content during fermentation (adjusted R²=0.84). Soluble solid was a good index for protein degradation in fermentation (adjusted R²=0.71). Proteolytic activity in Pacific whiting and its by-products were investigated using hemoglobin as substrate. Specific substrates and specific inhibitors were also used to classify the types of enzymes responsible for protein degradation in fish sauce fermentation. Serine proteases, cathepsin L-like enzymes and metalloproteases were active at 50°C in whole fish. However, trypsin-like enzymes, and cathepsin L-like enzymes were responsible for protein degradation in by-products at 50°C. At 35°, whole fish was degraded by serine proteases, cathepsin B-like enzymes, trypsin-like enzymes, and metalloproteases. Cysteine proteases were mainly responsible for the degradation of proteins in by-products, and serine proteases and trypsin-like enzymes had a minor role in hydrolyzing of by-products during fermentation. / Graduation date: 2000

Graduation date: 1997

Biochemical properties, functional properties, and market potential of Pacific whiting (PW) fish sauce were investigated. Biochemical properties of fish sauce made from whole fish (W) and a mixture (1:1) of whole fish and surimi byproducts (WB) were compared. Market potential was evaluated through phone interviews and consumer panelists. Proteolysis was primarily affected by cathepsin B-like and L-like enzymes. Acidic pH (4-5) with low salt concentration (15-20%) provided a greater degree of hydrolysis (DH), total nitrogen, and amino nitrogen content in PW fish sauce compared to the traditional process. The greatest Angiotensin Converting Enzyme (ACE) inhibition (96.8%) was found in samples fermented with 15% salt at pH 5.0 for 30 days. Anti-oxidative activity (AT) increased when fermentation continued and depended on fermentation pH. Peptides with MW <590 Da possibly played an important role in ACE inhibition. Consumer tests disclosed no significant difference in flavor liking and overall liking among fish sauce samples (W, WB, and commercial anchovy fish sauce). / Graduation date: 2004