What happens to yeast if there is a lack of certain ions in the brewing water?

Yeast is a living organism that relies on various nutrients and ions to function optimally during fermentation. The presence of certain ions, such as calcium, magnesium, sulfate, and chloride, plays a critical role in yeast health and metabolism.

When there is a lack of these essential ions in the brewing water, yeast can experience stress. This stress can manifest in several ways, including impaired fermentation activity, decreased reproduction rates, and the production of off-flavors. Specifically, a deficiency in ions can hinder enzyme activity necessary for energy production and metabolic processes that support fermentation.

As a result, the yeast may fail to ferment sugars properly, leading to incomplete fermentation and potentially leaving excess unfermented sugars in the final product. This can ultimately affect the flavor, aroma, and overall quality of the beer, as well as its alcohol content. Therefore, the correct answer indicates that a lack of certain ions can indeed lead to yeast stress and fermentation failures.