| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 86 === AbstractMuscle of tilapia（Orechromis niloticus）was stored
under high hydrostatic pressure from 500 to 3,000 atm for 12 hr
at 25℃ to investigate the changes of freshness and the
denaturation of muscle proteins. The tilapia muscle after
pressurizing was also stored at normal condition（25℃, 1 atm）
to determine the changes of K values and microorganism numbers
in order to investigate the effect of high pressure on the
inhibition of putrefactive factors in the muscle. The results
obtained were as follows:1. The pH of tilapia muscle stored at
lower pressure（500-1,000 atm） decreased, but pH increased
for that was stored over 1,000 atm. pH of the muscle did not
change apparently with elongating time. The phenomenon
indicated that the development of rigor mortis of pressurized
tilapia muscle was not obvious.2. K value of tilapia muscle
stored under high pressure increased slower than those stored
at normal condition. The result indicated that pressure can
keep the freshness of tilapia muscle.3. VBN of tilapia muscle
stored at normal condition increased during storage. However,
VBN was similar to that of fresh muscle when the storing
pressure was higher than 2,000 atm.4. The "L" , "b" values and
white index of tilapia muscle stored under high pressure
increased rapidly with increasing pressure, but "a" value was
the reverse. The appearance of tilapia muscle turned white
in high pressure.5. Total plate counts and psychrophilic
bacteria counts in tilapia muscle stored under high pressure
decreased with increasing time. Psychrophilic bacteria would
be killed when the muscle was stored at the pressure over
2,000 atm.6. The gel-forming property of tilapia muscle stored
at 500 atm increased, but a decreasing trend was observed
from 1,000 to 3,000 atm. Storage under pressure higher than
1,000 atm would result tilapia muscle in decrease of its
processing quality.7. The extraction of tilapia actomyosin
decreased with increasing pressure, and it was below 10% when
the treating pressure was higher than 2,000 atm. But the
activity of actomyosin Ca-ATPase from tilapia muscle stored
under high pressure was still maintained.8. According to the
analysis of protein solubility, DSC, SEM, and SDS-PAGE, the
critical pressure induced tilapia protein denaturation was
about 2,000 atm.9. The putrefactive factors of tilapia muscle
were inhibited but not entirely destroyed during pressure
storage. The result indicated that tilapia muscle had to be
stored jointly with other ways after high pressure storage to
maintain its freshness and processing property.
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