Brewers' yeast was the most important factor for the beer quality, especially for its flavor. There were. many factors which can cause the yeast autolysis and then influence the beer quality.

This was soon overcome by the use of baker's yeast which is a primary grown yeast which is a much cleaner yeast than the brewers yeast that have the residual effect of hops.

These extracts were basically produced from bakers or brewers yeast using a simple autolysis procedure.