johnnyboy1965 said:
OK, then, so so called experts/troll hunters. You try to tell me about yeast..there is a member on this site "saycr, forget his name, who bviously studied micro/macro biology, s I did.
I don't suppose that there was any biochemistry on that course? . . . if 1965 is your birth year, then even your A levels would have had the basic biochemistry to point out WHY you are so fundamentally wrong.
Sugar is not just a white crystalline compound you get from supermarkets / brew shops
Saccharides are the correct term for molecules that (As far as we are concerned - I'm ignoring ribose) have a chemical formula C6H12O6(n) where n is a number between 1 and many millions. The two prime saccharides that yeast ferment are glucose and fructose, but they have the enzymes to split the disaccharides sucrose (Glucose joined in a hydrolysis reaction with Fructose) and maltose (Two glucose molecules) . . .they can't ferment Lactose (Glucose and Galactose, as they can't produce the enzyme to split the bond). In a wort there also exist trisaccharides, like malto-triose which can be fermented by some yeast strains (mainly lager ones IIRC), as well as longer chain saccharides like malto-tetrose which are unfermentable. . . . and that is before we get to the polysaccharides like starch, Lignin and Cellulose
As others have said not all sugar is fermentable by all strains of yeast, just as not all sugars are glucose, so your assertion that yeast will continue to ferment, until all the 'sugar' has gone is completely false. Given an environment that is favourable to yeast metabolism, then yeast will metabolise the fermentable sugars present, unless that creates an environment inimical to yeast metabolism (excess CO2, excess ethanol etc). This is why beer, unlike wine, does not ferment below 1.000 and in fact should stop at around 1/4 of the original gravity. So given a 1.040 wort the expected FG is 1.010,
if the fermentation is carried out at a constant temperature, and
if sufficient healthy yeast are pitched. However, many people have seen that often fermentation will finish sooner than this say at 1.020 . . . this is termed 'Stuck' . . . it may or may not be possible to restart the fermentation, or to get it to eak out a few more gravity points. Why has it stuck?? Various reasons, possibly that the wort is deficient in things like FAN (Free Amino Nitrogen)or other nutrients, the temperature could be too variable for the yeast strain, Insufficient yeast were pitched, or the Brewer believed what someone said on the internet and only did a 15-30 minute mash. Yes they got a converted mash, but the ratio of fermentable to non fermentable saccharides was completely wrong.
johnnyboy1965 said:
Not fuming...little disappointed, but its your loss. I gave my educated opinion
:whistle: Read the Sig