Have you ever poured a beer or taken a sip from a bottle and noticed a cloudy layer of white substance at the bottom? Various theories have circulated regarding this substance, but most of them are inaccurate. Here’s the truth.
Yeast, Not Wheat
You might have observed that this mysterious cloudy layer often appears in wheat beers, leading to theories that it is wheat added to enhance the flavor. However, it is not wheat; it consists of dead or dormant yeast cells, and they are supposed to be present. In certain styles of wheat beer, these yeast cells do contribute to the flavor, but their primary purpose is carbonation.
Carbonation—Forced and Natural
There are two methods of carbonating beer. The first is forced carbonation, which involves injecting a measured amount of carbon dioxide gas (CO2) into a sealed container filled with cold, flat beer. More gas is pumped in than the container can actually hold, creating pressure. Gradually, the beer absorbs most of the gas and becomes carbonated. This is why beer and other carbonated beverages remain fizzy even after opening the container.
The other method is natural fermentation. It entails adding a small amount of sugar to the beer before bottling. In this case, the remaining suspended yeast in the liquid consumes the sugar, fermenting it into alcohol and CO2. The alcohol produced during this secondary fermentation is negligible, but the resulting CO2 is sufficient to carbonate the beer.
Similar to forced carbonation, the CO2 generated through natural fermentation exceeds the container’s capacity, so the beer absorbs it. While the sugar is being fermented, the yeast also reproduces, but eventually dies or becomes dormant, settling at the bottom of the bottle as the whitish layer.
Does Yeast Affect the Flavor?
In most cases, the dead or dormant yeast cells collected at the bottom of your beer bottle have minimal impact on the beer’s flavor. Yeast can cause the beer to appear cloudier, especially when poured into a clear glass, but that’s about it. However, in certain styles of wheat beer, the yeast does contribute to the flavor, often adding a slight spiciness. This flavor is heightened if the yeast is mixed in with the beer as it is poured.