| Summary: | 碩士 === 國立中興大學 === 生物科技學研究所 === 107 === The present study was aimed to assess inhibitory effect of alternating current electric field (ACEF) strength on the browning degree of oyster mushrooms (Pleurotus ostreatus, P. ostreatus) and the mechanisms. The results showed that pre-treatment of P. ostreatus with ACEF (600 kV/m, 50 Hz, 120 min) reduced the browning about 40 %, the malondialdehyde content about 30 %, the polyphenol loss rate about 30%, the enzyme activity about 40-80 %, and increase cell membrane integrity about 40%. According to the enzyme kinetics results analysis, the ACEF can simultaneously reduce the maximum reaction rate of the enzymes and the affinity with the substrate. The results of structural analysis show that the alternating electric field does not destroy the primary structure of the enzymes, only affecting the secondary and tertiary structure of the enzymes, and reduce the contact ability of the active end of the enzyme with the substrate. Different from some chemical inhibitors or more severe means to destroy enzymes, it has less influence on nutrients and is a milder preservation method. The results confirm that the ACEF can maintain the appearance color of P. ostreatus, improving the loss of phenolic compounds and inhibiting the activity of enzymes during storage, moreover; ACEF can maintain the integrity of the cell membrane of P. ostreatus and does not destroy the structure of the enzyme, thereby extending its shelf life.
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