I am interested in the historical basis of the germination processing of grains as a cheap technology for the biological enrichment of common food grains.
brotos comestiveis scielo in the google and you will find many papers with English Abstract.
In my opinion, the origin is Japan because it is a common food in Japanese restaurants in Brazil, but probably some original text, if any, is written in Japanese, too.
The best site to find some information in Brazil is EMBRAPA - Alimentos where some research can have this information.
1) "Steeping the grain induces sprouting and the synthesis of amylase enzymes that decompose the starch of the grain into sugar, a process that is aided by heated water and/or baking." I talk about beer. The oldest documentary evidence of beer brewing comes from Uruk in Mesopotamia and dates to about 3500 B.C.E..