When making liquor (like sake) from a starchy substance (like rice), the starch must be changed to sugar with the enzyme action of a substance (like saliva).
…Wait, what?
It’s true. The first sake in Japan was made at big rice-chewing parties. Everyone in the village would show up, chew some raw rice, spit it into a container, then go back home, content in the knowledge that they would soon gather for another village party, this time fueled by spit-soaked sake, known as kuchikami no sake, “chewing-in-the-mouth sake.” After the chewing party, water would be added to the saliva-rice and then the mixture would be monitored until it smelled alcoholic—what poor sap had that job? and was he likely to drink the most or least at the party?—at which point, everyone would gather again to drink their very communal concoction.
This type of liquor is not exclusive to Japan; in South and Central America as well as other parts of Asia, people were chewing their way toward drunkenness during the seventh through tenth centuries. In Taiwan, the custom was practiced until the early twentieth century. In Hokkaido and Okinawa, the northernmost and southernmost parts of Japan, they prepared the drink for special festivals and only women chewed the rice.
Luckily, koji was discovered, a useful little mold which not only turned starch into sugar for sake, but also came to be used to make miso, natto and soy sauce. Where would Japan be without you, Aspergillus oryzae?
…Drinking a whole lot of backwash, that’s where.
The primo stuff was chewed exclusively by female virgins. Mexico has a similar chewed beverage called pulque, pre-gummed by old ladies. Strictly for those who can't afford tequila!