牛乳凝固酵素に関する研究

Abstract

The milk coagulating function by enzyme in the fig latex (ficin) and by the extracts of the testicles of animal (rabbit, cow and pig) were studied. The results were as follows.(1) Ficin, especially fresh latex of fig, was very powerful in the coagulation of milk. Coagulating ability decreased by 50% during the process of alcohol precipitation and drying. It is desirable that the powder will be stored in the dark and vacuum place.(2) HCN, cysteine, NaH2PO2 and Na2S2O3 activated its coagulating activity. Phenylhydrazine and hydroxylamine activated at first and then inhibited when the weak enzyme was used. H2O2 remarkably inactivated milk coagulating action of ficin.(3) Milk coagulating activity of ficin was relatively stable in the high temperature. Its optimum temperature was also higher than that of rennin. Heated whey showed the activating action on coagulation by ficin.(4) Increase of acidity and Ca ion does not so much strengthen the activity of ficin as that of rennin. The milk, which was treated with rennet but the coagulation of which was stopped by the addition of oxalate, was clotted by the action of ficin. And in this case coagulation occurred more rapidly than in the case where ficin was used alone.(5) The yield of protein clotted by ficin was somewhat less than that by rennet, especially when powerful ficin was used.(6) Generally speaking, the extract of testicles had little or no ability to clot the normal milk (acidity 2.0cc). When its proteolytic activity was measured on pig testicles by a colorimetric micromethod for estimating peptic action, two optimum pH were found (pH 1.9 and 4.0).