Effects of Sugar and Fat on Fermentation
I am wondering why so many people erroneously assume that (a) fat inhibits fermentation, and (b) sugar increases fermentation.
When I tell people that sugar (in concentrations above 10-12%) inhibits fermentation because of its hygroscopic properties, they look at me funny and dismiss it (although perhaps the word "hygroscopic" is the cause for that funny look). Their logic is always: "yeast loves sugar. More sugar = happier yeast. Happier yeast = faster fermentation".
With fat, the opposite happens. People automatically assume that doughs with high proportions of fat are "heavy" and ferment slowly. This, again, is wrong. Fat has no effect on fermentation. "Try making a brioche" I say, to no avail. I think that often doughs with large amounts of fat also have a lot of sugar in them, which is the yeast inhibitor. People, however, are sure that sugar can't be the yeast inhibitor -- so fat must be the culprit.
What are your thoughts on the matter?