Safale S-04 – A Guide To Using S-04 Yeast

Safale S-04 by Fermentis is possibly the most popular dry English ale yeast on the market. It is the yeast I have most experience of using both as a homebrewer and as a commercial brewer. 

S-04 is a British yeast strain that is highly flocculent and fermentation times are pretty quick. This is what made it great for brewing cask ales in a commercial brewery setting where you want the yeast to settle quickly after a beer racked in a cask. 

Safale S-04 also has plenty to offer the home brewer too and some of its characteristics make it good for brewing drinks other than beer so let’s take a look.

Safale S-04 Profile

As mentioned above, Safale S-04 is perfectly suited to brewing cask ales because it ferments quickly and flocculates quickly.

S-04 Flocculation

When beer is packaged into a cask a certain amount of yeast goes into it. When cask beer is delivered to a pub the yeast gets roused back into suspension and the sooner it flocculates the better the beer clarity will be when served. Typically this means cask beer can be served in a couple of days of delivery into the cellar.

Fast Fermenter

The speed if fermentation from S-04 can catch you off guard. In just 2 or 3 of days of activity and the krausen (yeast head) at the height of fermentation will fall back into the beer.

I have seen countless threads in forums and questions asked here about whether the yeast is working properly when in reality it is doing exactly as intended.

S-04 Attenuation

At the recommended fermentation temperature of 20°C, the attenuation of S-04 is between 72 – 75%. This may be slightly affected by factors such as mash temperatures and grist.

In my experience, the attenuation from batch to batch using S-04 is very dependable.

Low Esters

The fermentation range suggested for Safale S-04 is between 15-20°C (59-68°F) which is fairly for a lot of ale yeast.

At this temperature, I personally have found there’s low discernable ester production. When you raise the temperature beyond 20°C / 68°F you might find more esters and other flavours are detectable, along with the higher temperature is a more vigorous fermentation.

Key Figures For Safale S-04

Fermentation Temperature: ideally 15-20°C (59-68°F) 

Flocculation: Very high

Attenuation: 72 – 75%

Alcohol Tolerance: 9 – 11% ABV

Yeast Cell Count: > 69,000,000,000 (69 billion) per 11.5g sachet

Safale S-04 Beer Styles

S-04 is recommended for many British and American beer styles and especially for cask ales, although this is less relevant to home brewers.

English IPA, ESB, Pale ales, blonde ales, stouts, porters, old ales, barleywines, red ales, mild, brown ales.

All these styles are suitable candidates for Safale S-04 as long as they are below 11% ABV at which point you might find residual sugars are under attenuated.

S-04 Unusual Uses

I have personally used S-04 for drinks that aren’t beer with good results.

I have made hydromel a lower ABV fruit mead, ginger beer and cider with S-04 and they have benefited from a little residual sweetness that is left by S-04 even when using simple sugars.

How To Pitch Safale S-04

Pitching dried yeast tends to be fairly simple.

There is, however, some confusion around whether yeast starters or rehydration is necessary or even detrimental but Fermentis has clear instructions on how to pitch S-04.

Direct Pitching

Fermentis have published themselves that yeast viability and profile are not affected if Safale S-04 is pitched directly onto the wort surface.

Pitching directly is simply a case of sprinkling the yeast directly from the package onto the wort covering the entire surface, avoiding clumps. There is no need for stirring or mixing the yeast in, the yeast will rehydrate in the wort and then sink into solution.

It is also suggested that pitching a few degrees above fermentation temperature is ideal. Pitching the yeast direct and then cooling down to fermentation temperature after pitching.

Rehydrating Prior To Pitching

Fermentis instructions indicate rehydrating the yeast in the following manner:

Sprinkle the yeast into 10 times its weight (115ml for 1 sachet) of sterile water or boiled wort at a temperature of 25 to 29°C (77°F to 84°F). Leave the yeast for 15 – 30 minutes before swirling the vessel and pitching into the wort.

How Long Does Safale S-04 Last?

The information published about S-04 suggests a shelf life of 36 months from production date. 

Yeast cell viability will decrease in this time so I would suggest rehydrating yeast before pitching if your yeast sachet is more than a year old. You might also consider making a yeast starter if your yeast is a couple of years old to ensure yeast health and build more healthy cells.

How To Store S-04

The ideal conditions to store S-04 and most dried yeast is in the fridge or at temperatures of less than 10°C / 50°F. 

Dried yeast can be stored at ambient temperature but the yeast viability will be less than it would if stored at cooler temperatures.

Once a package is opened it is recommended to use within 7 days.