I am interesting in making some Sake. Apparently, rice, unlike barley, does not contain the enzymes necessary to convert the starch into sugar, and the traditional method of making Saki involves combining steamed rice with Koji, a mold (Aspergillus Oryzae) that produces amylase enzyme, which is responsible for converting the starches in rice into sugar.
I thought it would be interesting to skip to Koji and instead use pure amylase enzyme instead. From what I've read, the end product would taste different because Koji imparts a particular taste into Saki, but I thought I would try. Some people on homebrewtalk have reported that they have used amylase enzyme instead of Koji successfully.
Given a quantity of rice, for example, 10 pounds, how do I calculate the neceessary amount of pure amalyze enzyme that would be required to convert all of the starches into sugar?