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
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26555 |
| Date | 04 June 1999 |
| Creators | Lopetcharat, Kannapon |
| Contributors | Park, Jae W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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