>Also ethanol is now obtained commercialy from sweet milk whey which
>is high in the sugar lactose. Do they use lactase to split the
>lactose into glucose and galactose then use a saccharomyces yeast, or
>do they use the lactose fermenting yeast kluyveromyces marxianus?
>Does the galactose ferment into ethanol?
I've just collected my "interloan" copy of "The Alcohol Textbook" from my
local library, and its got a bit about this in it... I'll summarise the
main points ...
* Whey generally contains 4.8% lactose, 0.6% protein, 0.6% salts and 0.05%
* Lactose is a disaccharide composed of glucose and galactose
* Normal distillers yeast (Saccharomyces cervisiae) will ferment galactose
only very slowly, and only if no glucose is present. Not considered
economically feasible (can be done, but need huge excesses of yeast & long
* one particular species will work, Kluyveromyces marxianus, variety
marxianus (previously known as K.fragilis). Its not available commercially
in dried form.
* you can only expect to obtain about 2.5% by volume of alcohol
*much of the technology is proprietry.
re your other question : fructose is very fermentable.