What is the difference between SafAle 04 and 05?

Answered by Jarrod Smith

SafAle S-04 and SafAle US-05 are both popular yeast strains known for their cold-tolerant and fast fermentation characteristics. However, there are some notable differences between the two.

One key difference is in their attenuation levels. Attenuation refers to the yeast’s ability to convert sugars into alcohol during fermentation. S-04 has lower attenuation compared to US-05, meaning it will leave behind more residual sugars and result in a slightly sweeter finished beer. On the other hand, US-05 has higher attenuation, leading to a drier and crisper beer.

Another difference lies in the flavor profiles produced by these yeasts. S-04 tends to be more fruity and minerally, with some ester and phenolic characteristics. This can contribute to a more complex and flavorful beer, particularly at lower fermentation temperatures ranging from 58º F to 64º F. In contrast, US-05 is known for its clean and neutral flavor profile, making it ideal for producing beers where the focus is on the malt and hop flavors. It shines particularly at moderate ale fermentation temperatures ranging from 65º F to 69º F.

In terms of performance, both yeasts are highly reliable and efficient. They are known for their fast and vigorous fermentation, often completing fermentation within a relatively short period of time. This can be beneficial for homebrewers and commercial brewers alike who are looking for a quick turnaround time.

I have personally used both SafAle S-04 and US-05 in various brewing projects. When I wanted to brew a British-style ale with some fruity and estery notes, I opted for S-04 and fermented it at a lower temperature range. The resulting beer had a pleasant fruity aroma and a slightly sweeter taste. On the other hand, when I wanted to brew a clean and crisp American-style pale ale, I chose US-05 and fermented it at a moderate temperature range. The beer turned out to be clean and showcased the hop and malt flavors beautifully.

To summarize, SafAle S-04 and SafAle US-05 are both excellent yeast strains with their own unique characteristics. S-04 attenuates less, resulting in a slightly sweeter beer with fruity and minerally flavors, especially at lower temperatures. US-05, on the other hand, is cleaner and more neutral, making it a great choice for beers where the malt and hop flavors take center stage, especially at moderate ale temperatures.