| Summary: | 碩士 === 國立海洋大學 === 水產食品科學系 === 85 === Abstract Fish essence produced from mackerel was studied by a
method modified from theprocess of producing traditional chicken
essence. Protein extractions were carried out at either pH 6.0
or pH 8.0 for 10 min. at temperature ranging from 5 to 120℃
with the addition of Na salt. Results showed that more protein
was recovered at pH 8.0 and as the temperature lowered. However,
essence extracted at temperature 50℃ or below would gelatinize
during subsequent heating which is necessary for clarifying and
pasteurization purposes which made it unsuitable to operate
below 50℃. DSC suggested thatthis may be due to a partial
degradation of myosin head during a prolong frozen storage of
the mackerel. There was no significant difference of the amount
of protein extracted between 120 and 50℃ while the TCA soluble
nitrogen was significant higher for sample extracted at 50℃.
Thus, the highest yield of fish essence extraction was found to
be at pH 6.0, 50℃ with the addition 0.03M NaCl. Results of
amino acid analysis suggested that fish essence has
significantly higher His and Tau content, the predominated amino
acids in the product, than commercial chicken essence. On the
other hand, the amino acid derivatives, Ans and Car, were the
predominated compounds in chicken essence which were not present
in fish essence.Endogenous protease hydrolysis of muscle protein
was further investigated. Results showed that there was a
synergistic effect of Na and Ca to protein degradation for
chicken muscle with an optimum pH at 4.0. For mackerel, however,
the highest TCA soluble nitrogen were found at pH 4.9 with the
presence of Ca alone. The K value of mackerel muscle
hydrolysates suggested that the time of autolysis must be less
than 6 hr. Inosine was the most from the extraction with
homogenization and 2% NaCl. The extraction with 0.5% CaCl2 the
quantity of GMP was the highest and in that with 2% NaCl and
0.5% CaCl2 the most one was IMP. Besides, the lowest quantity
ofHypoxanthine was obtained by extraction with 2% NaCl when the
autolysis time of mackerel was at 6 hr.
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