The fed-batch culture has been practiced since the early 1900s, when it was recognized
in yeast production from malt wort that the malt concentration in the medium
had to be kept low enough to suppress alcohol formation and maximize the yield3 of
yeast cells. High malt concentration would accelerate the cell growth, which in turn
would cause anaerobic conditions that favored ethanol formation and lowered the
yield of yeast cells. Additional wort was added at a rate that was always less than
the rate at which the yeast cells could use it. Intermittent or incremental feeding of
nutrients to an initially dilute medium was introduced thereafter in large-scale yeast
production to improve the yeast yields while obviating the production of ethanol.4
However, there is some speculation that a small amount of ethanol may be necessary
to ensure the quality of the baker’s yeasts.