EFFECT OF CATHEPSINS ON TEXTURAL CHANGE DURING RIPENING OF IKA-SHIOKARA (SALTED SQUID PRESERVES)

We attempted to discover whether cathepsins of squid Todarodes pacific us mantle muscle and liver have an effect on the textural change of ik a-shiokara (salted squid preserves) during ripening was examined. The existence of cathepsin D-like, B-like, and L-like enzymes (D, B, and L ) in the two tissues was ascertained from the effects of pH and inhibi tors on the hydrolysis of hemoglobin, Z-Arg-Arg-MCA, and Z-Phe-Arg-MCA by enzyme preparations. Every muscle enzyme was almost completely inh ibited in the presence of 7% (w/v) NaCl, whereas liver B and L were co nsiderably stable even in 15% NaCl. During the ripening of shiokara ma de by mixing muscle and liver with the addition of 7% NaCl and 3 mm Na N3, the specific activity of muscle B and L increased with the penetra tion of liver enzymes to the muscle, and a remarkable hydrolysis of my ofibrillar proteins accompanying the organoleptic softening of texture was observed after 3 days' ripening by SDS-polyacrylamide gel electro phoresis. Under the present experimental condition, the effect of bact eria on the ripening of shiokara seemed to be negligible. From these r esults, the hydrolysis of myofibrils by liver cathepsin B and L seemed to be involved in the textural change of ika-shiokara during ripening .