Flour and yeast question.

[bernardsmith]

If I brew beer I need to be sure that the enzymes in the grain are activated for the starches to be broken down into simpler sugars the yeast can ferment. When I make sourdough bread I simply add the yeast and bacteria culture to unmalted flour at room temperature (or even colder) and over time the yeast produce enough CO2 to give me a well-risen dough. What are the yeast eating? And if they are eating simple sugars where are those simple sugars coming from? Thanks - and in anticipation of midnight: A happy, healthy and safe New Year.

 

[Robert65]

There are amylase enzymes in the flour, in all flour and grains. When we malt the grain and raise the temperature of the mash, we make the process go faster, but remember, nature intended the enzymes to work in a seed in the cold, damp dirt. All the enzymes we deal with are active as soon as they meet water, at any temperature, though we identify "optimal" temperatures for mashing. So they will, in the presence of moisture in the dough, break down starch into sugar fast enough to feed yeast. If it went as fast as in mashing, you would never get bread dough, just a puddle of wort in your mixing bowl. (Note that the higher amylase content of rye is one reason we need sourdough to make rye bread, using the acidity to restrain amylase activity, so as to avoid runaway starch degradation leading to gummy dough and bread.)

In addition, yeast and bacteria can produce their own enzymes to convert starch. Again, they'll work fast enough for their own purposes, but asking them to make beer from raw starch in water would be too great a task, they'd exhaust themselves before making a dent.

Happy New Year!

 

[bernardsmith]

Many thanks for this explanation. Makes a great deal of sense but I guess I always assumed that the enzymes in the seed required the seed to sprout for them to be active. Your explanation provided me with a different explanation and one that makes good sense in terms of my own observations. Happy New Year to you, Rob