| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 85 === The gel strength, whiteness, and water holding capacity of
theminced milkfish gel induced by heating, heating after
pressurizing,and two-step heating heating were compared.
Enzymatic activity of temperature, pH, hydrostatic
pressurization, and heat treatment on the protease activity were
also investigated. The results obtainedwere as follows:1.The
suwari of unwashed milkfish meat paste occurred at 50℃,while
the modori occurred at 60℃ and 70℃. The gel strength of the
washed meat paste was higher than that of unwashed. But the same
tendency in thermally induced gelation was observed.2.Whiteness
of milkfish gel increased with the increase of heating
temperature at 30~60℃. No obvious changes were observed at 60℃
and 70℃. Water holding capacity of thermally induced gel
decreased with the increase of heating temperature. Two-step
heating treatment improved the gel strength and whiteness of
gel, but deteriorated the water holding capacity of gel.3.High
pressure treatment could improve meat paste in suwari and
inhibitin modori. Gel strength. whiteness, and water holding
capacity of gelobtained by heating at 30 ~ 70 ℃ could be
improved by pressurizing at 3,000 atm for 30 min as
pretreatment.4.The alkaline extracted from milkfish showed the
maximum enzymatic activity at 60 ℃, pH 8.0 against 5%
Hammarsten casein as subatrate. The alkalineprotease was
activated by heating at 50 ℃ for 10 ~20 min, byt was
inactivated by heating 40, 50 and 60 ℃ for 120 min. Enzymatic
activity decreased with increasing pressure (~4,000 atn ) and
pressurizing time (~ 30 min). The fact, alkaline protease
treated at 4,000 atm for 10 min was almostcompletely
inactibated, indicated that the protease was susceptible to
pressure.
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