• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.114-120
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• 1994

To clarify the effect of storage temperature on the morphological and histological changes of plaice, Paralichthys olivaceus muscle at early stages after killing, the changes in breaking strength of muscle, morphological observation of myofibrils and histological observation of extracellular spaces during storage at $0^{\circ}C\;and\;10^{\circ}C$ were studied. The maximum breaking strength of samples stored at $0^{\circ}C$ was reached within 10hrs and then it dropped significantly (p<0.05) from 10hrs to 25hrs of storage. However, breaking strength was not increased in fresh muscle stored at $10^{\circ}C$ and gradually decreased after 10hrs storage. In myofibrils prepared from dorsal muscle immediately after death, A-band, I-band, H-band and Z-line in sarcomere were clearly distinguishable from each other. Due to muscle contraction, it was not easy to distinguish H-band from I-band observed in sarcomere stored at $0^{\circ}C$ after 10hrs storage. But, in the case of samples stored at $10^{\circ}C$, H-band could be observed dimly until 15hrs of storage. The changes in morphological myofibrils were closely related to increase of breaking strength. No extracellular space was observed among muscle cells immediately after killing. Stored samples at $0^{\circ}C$ showed extracellular spaces after 15hrs storage. On the other hand, samples stored at $10^{\circ}C$ didn't show any extracellular spaces until 15hrs storage and showed extracellular spaces after 24hrs storage. It was thought that the post-mortem tenderization of plaice muscle was closely related to the gradually disintegration of the extracellular matrix structure after killing.

• Korean Journal of Food Science and Technology
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• v.7 no.4
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• pp.229-237
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• 1975

An attempt was made to utilize the enzyme produced by Asp. oryzae as meat tenderizer. The production, purification, and various properties of proteinase produced by Asp. oryzae were investigated. Results obtained are as follow; 1. A strain which had the highest proteolytic activity was selected among 9 Aspergillus species. 2. Culture medium consisted of wheat bran 10g, 2% glucose, 0.03% urea and 0.1% $MgSO_4$ (pH 6.5). Mold was incubated at $30^{\circ}C$ for 3 days. 3. Enzyme extract from culture medium were fractionated with ammonium sulfate and purified by Sephadex G-75 column chromatography. 4. When pH of reaction mixture was controlled, maximal activity of proteinase by Asp. oryzae was obtained at pH 3, pH 6.6, $8.4{\sim}8.5$ and pH 10.0 to 10.5. Those results were interpreted to show that enzyme consists of acid proteinase, neutral proteinase and alkaline proteinase. Enzyme was stable at pH 6 to 10. 5. Opt. temperature for proteinase activity was $50^{\circ}C$, but enzyme was stable up to $40^{\circ}C$. 6. The proteinase was inhibited by $Ag^+$. It was also inhibited by EDTA. 7. When myofibrillar proteins were treated by proteinase from Asp. oryzae, ATPase activities of myofibrillar proteins changed remarkably. Accordingly, it was concluded that proteinase produced by Asp. oryzae were able to be used as meat tenderizer.