• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.791-798
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• 1998

To develop natural flavoring substances. optimal hydrolysis conditions for two stage enzyme hydrolysates (TSEH) using low-utilized shellfishes such as purplish clam and frozen oyster stored at $-20^{\circ}C$ for 60 days. The optimal conditions for TSEH method were revealed in temperature at $50^{\circ}C$ 3 hours digestion with alcalase (Aroase AP-10, $0.3%$ w/v, pH 8.0) at the 1st stage and $45^{\circ}C$ 2 hours digestion with neutrase (Pandidase NP-2, $0.3\%$ w/v, pH 6.0) at the 2nd stage. Among water extracts, autolytic extracts and 4 kinds of enzyme hydrolysates tests, TSEH method was superior to other methods on the aspect of yields, nitrogen contents, taste such as umami and control of off-flayer formation, and transparency of extracts. From the results of chemical experiments and sensory evaluation, we may conclude that TSEH from low-utilized marine products is more flavorable compared the conventional enzyme hydrolysates, it could be commercialized as the seasoning substances.

• Journal of Dairy Science and Biotechnology
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• v.14 no.2
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• pp.157-164
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• 1996

This study aimed increase the quality during ripening of Cheddar cheese made with proteinase-negative mutant of Streptococcus lactis KCTC 1913 selected by curing. The degradation of protein during cheese ripening were investigated by electrophoresis and chromatography. The results were summarized as follow ; 1. The number of lactic acid bacteria decreased with the ripening stage, and that of the control cheese decreased faster than that of the cheese made with mutant. 2. Polyacrylamide gel electrophoretic analysis of cheese caseins revealed no difference between the cheese made with mutant and the control cheese, but differences along with the ripening stage were evident. 3. On Sephadex G-25 column chromatography, the extracts of bitter components from the green cheese and 3 month ripended cheese were fractionated into 3 fractions. With the progress of ripening, bitter peptides were degraded to rather small peptides or free amino acids. 4. Sensory evaluation of the 3 month ripended Cheddar cheese found no significant differences in color but the cheese made with mutant evidenced higher palatability in flavor and better texture than the control cheese. 5. The yields of the cheddar cheese made with mutant was 0.14% higher than that of the control cheese.