Previously, I posted a blog about the benefits of mold and fungi in the environment, in food production, and its potential as a future energy source. In this post, I would like to focus on mold in a more specific context: how mold impacts the brewing industry – my personal favorite.
Let’s start off with some basic information about brewing. The fundamental ingredients for beer are water, yeast, hops, and some sort of starch (usually barley). Other adjunct grains like corn, wheat, rye, sorghum or rice can be used instead of or in addition to barley. Basically, the grain is boiled in water to produce sugars. This boiled product is called wort. Hops are added to the boiling sugar-rich wort for flavor. A general term for the mixing and combination of grains is mashing and the product can be called mash. The mash is cooled and yeast is added to the hopped wort for the microorganism to convert the sugars in the wort into alcohol. This is known as the fermentation process.
Yeast, Mold, & Fungi
Yeast is a crucial organism that belongs to the same biological kingdom as mold. Mold and yeast are both a type of fungus. There are several different types of yeast that are used in brewing but two examples of commonly used yeasts are Saccharomyces cerevisiae and Saccharomyces pastorianus https://beerandbrewing.com/what-is-the-difference-between-ale-and-lager/. . S. cerevisiae ferments at higher temperatures and produces ales https://beerandbrewing.com/what-is-the-difference-between-ale-and-lager/. . S. pastorianus typically ferments at a lower temperature for a longer period of time and produces lagers https://beerandbrewing.com/what-is-the-difference-between-ale-and-lager/. . Brettanomyces yeast is also commonly used to make funkier styles of beer such as sours and lambics. The word funkier is used purposefully because some of these beers can be described as having a funky flavor profile.
In one of our more recent blog posts, mycotoxins were defined as chemical compounds that are generated from toxigenic fungi. Mycotoxins can be introduced into the wort from moldy, low-quality grains. Fusarium is a common mold type that can be found on barley. When barley is boiled it germinates and then interacts with Fusarium mold to produce mycotoxins such as Deoxynivalenol (DON) https://www.ncbi.nlm.nih.gov/pubmed/11922090. . The mycotoxins generated can affect the ability of the yeast to convert sugars into alcohol.
When tasting beer there are several words that can be used to describe the flavor profile. A more bitter India Pale Ale (IPA) may be described as hoppy. A wheat Hefeweizen may be described as malty with hints of banana. Unappealing flavors, also known as “off-flavors”, can also be used to describe beer. If the beer tastes like floor cleaner it can be described as having a solvent flavor (and not to mention something went horribly wrong in the brewing process!). Mold can grow on unclean brewing equipment. If beer is described as “musty” it likely was subjected to moldy conditions. However, there is one particular beer style known as “Biere de Garde” where a musty odor is expected and welcomed.
In many of our blog posts, we focus on the negative effects of mold and fungus. However, it is important to remember that mold is a part of nature and it plays a vital role in our environment. Just think, without fungi, there would be no beer. So cheers to mold and its critical contribution!