Why should I avoid glucose, table sugar, honey, apple juice, etc. in making yeast starters?
Brewer’s yeast has been selected for its ability to grow well in malt-based wort and produce pleasant by-products. In particular, yeast prefer to ferment maltose because it is the largest fermentable constituent in wort. Growing your yeast up in a non-malt environment can affect the health and you can get a disordered fermentation and possible off flavors in your beer. Growing up in a high glucose environment, for example, can result in selection in favor of respiratory mutants that cannot properly ferment maltose.
