I heard in the past about many superlative claims about the benefits of rice washings, rice water, etc.From.personal experience during my childhood days I watched my grandmother using the rice washing to water her orchids and noticed it produced flowers regularly than from my neighbor that have the same plant but was just watered by tap water and rarely it produce blossoms. .It seems to have growth factor in it from the layman’s perspective .
Now looking at it from Food Chemistry standpoint.Milled rice contains traces of rice flour ,rice starch, the rice endosperm itself contains mostly starch, little protein, little fiber, minerals like calcium, magnesium, potassium, and sodium,some types of Vitamin B is there. Summing it up parts of these components are leached out ,iif rice is steeped or washed in water to make rice washings a mild fertilizer and culture medium for microbes.
Therefore as rice is exposed to air,then airborne microbes that abound in cereals like pathogens clostridium perfringens, bacillus cereus, some enterococcus as well as lactic bacteria, yeast and molds spores .These cocktail of microbes are responsible for fermentation action if rice washings are stored. Hence vigorous gas generation ,carbon dioxide,nitrogen ,hydrogen, traces of hydrogen sulfide etc. .will cause your sealed plastic water bottle to bulge and deform… If you release the pressure you will get an offensive smell due to those gases.
Now if you allow it to ferment longer, gradually these pathogens are outnumbered by lactic bacteria ( homo and heterfermentative types)generating lactic acid, acetic acid, acetone, acetaldehyde resulting in a sour smell.Although these changes does not happen often as it depends on the environment as well.
Regarding its much hyped beneficial effect on skin.to me it’ a mixed bag : some suffers skin allergies. Its maybe because these allergic users utilized a pathogen infested rice washings and those that benefits it their rice washings are dominated by friendly non pathogenic lactobacteria.
In the same vein some people claim.similar benefit by applying sourdough starter to their skin and had nice tone. , become supple , etc.
So there you go, in theory if the rice washing attain similar microbial environment as sourdough starter it will give beneficial effect due to lactic acid and other components in the brew that promotes it.Otherwise it won’t…
Finally science still is skeptical about the claimed benefits ,but devoted users still do it.
