The attenuation of US-05 yeast, which is a ready to pitch American Ale yeast from Fermentis, is quite high with an apparent attenuation of 81%. This means that it has the ability to ferment a large portion of the sugars in the wort, resulting in a beer with a lower final gravity and potentially higher alcohol content.
Attenuation is an important factor to consider when brewing beer, as it directly affects the body and sweetness of the final product. Yeast strains with higher attenuation tend to produce drier and crisper beers, while those with lower attenuation can result in sweeter and fuller-bodied beers.
US-05 yeast is known for its clean and crisp profile, making it a popular choice for American-style ales. It is often used in a variety of beer styles, including pale ales, IPAs, and even stouts. I have personally used this yeast strain in several of my own homebrews and have always been satisfied with the results.
One of the advantages of using US-05 yeast is its ability to produce a beer with low diacetyl levels. Diacetyl is a compound that can give off flavors of butter or butterscotch if present in high levels. However, with US-05, you can expect a clean fermentation profile without these unwanted flavors.
When using US-05 yeast, it is important to take into account the fermentation temperature. Like many ale yeasts, it performs best at temperatures between 59-75°F (15-24°C). I have found that fermenting on the lower end of this range tends to produce a cleaner and crisper beer, while fermenting on the higher end can result in more fruity esters.
In terms of pitch rate, Fermentis recommends using one 11.5g sachet of US-05 yeast for a standard 5-gallon (19-liter) batch of beer with an original gravity of up to 1.060. For higher gravity beers, it is advisable to use multiple sachets or to make a yeast starter to ensure a healthy fermentation.
US-05 yeast is a reliable and versatile option for brewing American-style ales. Its high attenuation, low diacetyl production, and clean fermentation profile make it a popular choice among homebrewers and commercial brewers alike.