Selection of Commercial Enzymes Suitable for Making Soymilk-curd

A soymilk-clotting efficiency test was carried out with various commercial proteinases. The efficiency was relatively high in the cases of proteinases originating from Bacillus amyloliquefaciens, Bacillus subtilis, Aspergillus oryzae, Aspergillus sojae, Bacillus thermoproteolyticus and bromelain, while it was relatively low in those of Endothia parasitica, Rhizopus sp., Mucor miehei, papain and trypsin. Of the enzymes investigated, proteinases showing high proteolytic activity as to soymilk-protein also exhibited high soymilk-clotting efficiency. Such coagulation of soymilk-protein increased with the addition of CaCl2 or MgCl2 to the soymilk. The coagula, formed with enzymes showing high soymilk-clotting efficiency, could easily be separated into soymilk-curd and whey by centrifugation at 1600 × g for 2min. The volume ratio, after centrifugation of coagula formed at 5 min incubation with the enzymes, of soymilk-curd to whey was about 1:1, and the volume of the curd had a tendency to increase with increasing incubation time. The experimental results suggest that alkaline and neutral proteinases originating from microorganisms are suitable for making soymilk-curd on an industrial scale.