Effect of drying and storage condition on the properties of proteases from viscera of tuna (Thunnus albacares)
Wiphawan Trairatananukoon, M.Sc. Student in Biotech., PSU.
Poonsuk Prasertsan, Assoc. Prof., D. of Industrial Biotech., F. of Agro-Industry, PSU.
Saowaluck Jitbunjerdkul, Asst. Prof., D. of Food Tech., F. of Agro-Industry, PSU.
Corresponding e-mail : ppoonsuk@ratree.psu.ac.th
Grant : Graduate School, PSU.
Presented : The 12th Annual Meeting of the Thai Society for Biotechnology "Biotechnology :
Impacts & Trends", 1-3 November 2000, Kanchanaburi, Thailand
Key words : viscera, tuna, protease, drying, property
Proteolytic enzymes were extracted from the viscera of tuna (Thunnus albacares) using 0.05 M carbonate-bicarbonate buffer (pH 10.0) in the ratio-viscera to buffer of 1 : 2. The activities of protease, trypsin and chymotrypsin in the crude enzymes were determined by using casein, N-toluenesulfomyl-L-arginine methyl ester and benzoyl-L-tyrosine ethyl ester as substrates, respectively. The corresponding activities were 4.22, 0.11 and 0.07 U/ml.
The effect of two drying methods, spray-drying and freeze-drying, were compared. The yield and residual activity of freeze-dried enzyme were 87.6% and 64.2% whereas those of spray-dried enzyme were 24.8% and 70.8%, respectively. Therefore, freeze-drying gave 62.8% higher yield than spray-drying but the residual activity of the spray-dried enzyme was 6.6% higher. The influence of storage conditions on the activity of crude and freeze-dried enzymes were investigated at -20, 4 and 37oC for 90 days. Crude enzyme activity decreased rapidly after keeping at 37oC for 3 days and changes in color were observed after 6 days. After storage for 90 days at -20, 4 and 37oC, the residual activities of crude enzyme were 70.4, 81.7, 5.5% while those of freeze-dried enzyme were 97.5, 93.5, 70.2%, respectively.
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