| Summary: | 博士 === 國立臺灣大學 === 農業化學系 === 82 === Pork loin is the major meat product consumed in Taiwan, Pork
loin always suffer from the contanmination of large amount
of microorganisms.If the microorganisms are not inhibited or
des- troyed, it may cause meat spoilage and potential health
hazards. In recent years, gamma irradiation is effective in
eliminating microorganisms and extending the shief life of
food. The purposes of these studies were to evaluate the
effects of gamma irradiation on the reduction of microorganisms
and on the chemical change of meat constitutions. The results
showed that pork loin irradiated at 5oC or -18oC would
produce irradiation flavor, the threshold doses were 1.25 kGy
and 3.2 kGy respec- tively. the intensity of irradiation
flavor was well correlated with temperature and irradiation
dose, Gamma ray also inhibits pathogenic bacteria effectively
and the viability of pathogenic bacteria varied with dose,
medium and treatment. With a irradia- tion dose of 1.25 kGy at
5oC, the total bacteria count on pork loin were below 3 x 10
7 cells/g after 12 days storage, but not inhibit autolytic
enzymes, the meat shown worse quality after prolong storage.
In respect of nutrient, there were no signi- ficant changes
in vitamin B2,B5, B6, B12 and amino acids when irradiated at
7 kGy or less. The only exception is vitamin B1. Although
electrophoresis results showed that the sarcoplasmic
protein and myofibril undergo fragmentation, degradation
and polymerization at 50 and 100 kGy, but no significant
change in protein with a irradiation dose less than 10 kGy. As
a whole, low dose irradiation (1.25 kGy) could effectively
reduce the number of microorganisms, extended the shelf life
and cause no significant change in nutrients. However, the
inhibi- tion of proteolytic enzymes, need further investigation.
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