full2010.pdf - page 36

การประชุมวิ ชาการและเสนอผลงานวิจัย มหาวิ ทยาลัยทักษิ ณ ครั้งที่ 20 ประจำป 2553
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Autolysis and Biochemical Properties of Endogenous Proteinases
in Japanese Sandfish (Arctoscopus japonicus)
Sappasith Klomklao1*, Hideki Kishimura2, Soottawat Benjakul3 and Benjamin K. Simpson4
Abstract
Autolysis of Japanese sandfish (Arctoscopus japonicus) was studied. The highest autolysis
was observed at 60 °C. Optimal pH for autolysis was found at both acidic and alkaline pH values.
Autolytic activity decreased with increasing NaCl concentration. Further assay of the extract from
Japanese sandfish exhibited the maximum activity at 55 ° C and pH 9.5. The Japanese sandfish
proteinases were markedly inhibited by pepstatin A at pH 3.5, while soybean trypsin inhibitor,
PMSF and TLCK inhibited activities of proteinases at pH 9.5, suggesting Japanese sandfish
proteinases were both aspartic and serine proteinases. The extracts were stable to heat treatment up
to 50 °C for 15 min and still remained high relative activity after incubated at 50 ° C for up to 8 h.
Maximum stability of the extracts was observed between pH 6 and 11 and no changes of activity
were found after incubation at pH 9.5 for up to 8 h. Activity of Japanese sandfish extract
continuously decreased as NaCl concentration increased (0–30%), while activity increased as
CaCl2 concentration increased. The results suggest that major proteinases in Japanese
sandfish were trypsin-like serine proteinases.
Keywords: Autolysis, Degradation, Fish sauce, Protease, Proteolysis
1Department of Food Science and Technology, Faculty of Technology and Community Development, Thaksin
University, Phatthalung Campus, Phatthalung 93110, Thailand
*Corresponding author: Sappasith Klomklao, Fax: +66 7469 3996; e-mail:sappasith@tsu.ac.th
2Laboratory of Marine Products and Food Science, Research Faculty of Japan Fisheries Sciences, Hokkaido
University, Hokkaido 041-8611,
3Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla
90112, Thailand
4Department of Food Science and Agricultural Chemistry, McGill University, Quebec, H9X 3V9, Canada
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