How can I make rice mylk/milk that tastes sweet without adding sugars/sweeteners of any kind?

Question

This follows on from my question Is it safe to make mylk/milk from rice? which I realise was trying to ask two questions (if not three...)

I notice that the rice mylk I buy has a wonderful sweet taste, without the aftertaste of cane or beet sugar.

I have tried making rice mylk myself by blending soaked rice, and it has no sweetness (and tastes chalky).

It seems that the manufacturers of rice milk are using a clever fermentation process to break the rice starch down to natural sugars, as the Japanese have traditionally done when making amazake.

Is there any way I can achieve this myself? I don't want to add any kind of sweetening ingredients.

Answer 1

Fermentation is not the process you are looking for. What you want is mashing, which is the process of converting starches to sugars via the use of alpha-amylase proteins (aka enzymes). You will get the most information on this from the home brewing community, since mashing is the first step of an all-grain brewing process. Rice contains no natural a-amylase protein, so you will have to add some of your own. You can do this either by including an enzyme grain like barley in the mash (which would create a rice-barley milk) or by adding the pure a-amylase enzymes directly to the grains before the mash. You will then need to hydrate the grains and maintain them at the proper temperature for a period of time appropriate to the amount of sugars you want to be converted. I don't know the details on the process to make this work, but some research on all-grain brewing and a few trips to your local homebrew store should get you sorted.