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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?

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It's usually 1/2 oz of amylase per 10lb of enzyme free grain.

Each product of amylase may differ in dosage, but should be documented.

It will still need a mash of proper temp and ph.

Generally a cereal mash is used, which uses up to 50% enzyme grain to convert the non enzyme grain.

For 100% rice mash you will need amylase and rice hulls (lautering filter) and possibly an acid to reduce mash ph to 5.2-5.6

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  • So, 1/2 pound of amylase enzyme per 10 pound of enzyme free grain? Supposedly, I have to steam the rice which would add some water weight. the 10 pounds of enzyme free grain is the dry weight, correct? – Matthew Moisen Apr 10 '16 at 21:21
  • Is there anything wrong with dumping in an excess amount of amylase enzyme? – Matthew Moisen Apr 10 '16 at 21:21
  • 1/2 oz amylase per 10lb of grains. – Evil Zymurgist Apr 11 '16 at 1:12
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    @MatthewMoisen amylase is not tasty. Not really. So if your excess will be large enough to show in taste, it will be bad. But I don't know how much would that be. – Mołot Apr 11 '16 at 10:12
  • @Mołot thanks and good point; I'll dissolve some in a given quantity of water and see if I can identify it by taste – Matthew Moisen Apr 12 '16 at 2:32
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I put a quarter tablespoon of alpha-glucosidase powder into about 4 cups of cooked rice, and the rice turned super fragrant. I fermented that with champagned yeat and got something that tasted like Chinese sweet rice wine with low ABV. I'm not sure why the fermentation or the mashing didn't get farther and allow a greater ABV. I'd expect the amylase to fully convert the starch, but either it didn't fully ferment due to lack of nutrients, or it did ferment fully and the amylase stopped working.

Would be curious to hear how your experiment went.

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I'd bet that your result was probably because of temperature issues. Sounds like a case where the enzyme wasn't given an optimal temperature for the starch to sugar conversion process. Because that didn't happen, the yeast culture died out.

If you're taking this approach (replacing nuruk/koji mold with an enzyme), I'd recommend trying alpha amylase and also a separate process for the starch conversion using amylase... that way you can work it at a higher temperature (30 to 60degC at a roughly neutral pH), followed by a separate low temperature long duration yeast fermentation (around 10 to 15 degC).

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    Please make sure to answer the question: "Given a quantity of rice, for example, 10 pounds, how do I calculate the necessary amount of pure amalyze enzyme that would be required to convert all of the starches into sugar?" – Philippe May 1 '18 at 10:15

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