One of the great things about home brewing is the new avenues of exploration and opportunities to improve that open up to the inquisitive mind. There is always something new to learn and a way to improve that last batch of beer.
Consider yeasts. There are umpteen different strains to suit a plethora of beer styles, opening up a world of possibilities.
Before exploring the variety available, it’s necessary to consider that off-the-shelf yeasts fall one of two categories — dry and liquid.
Dry or liquid yeast?
Using dry yeast is simpler and more reliable for beginners while liquid yeast provides more variety and flexibility for experienced brewers seeking specific flavours.
Dry yeast is convenient, with a long shelf life and easy storage. It’s typically more forgiving in terms of handling, requiring minimal preparation — either sprinkle straight on top of the wort or rehydrate it before pitching. Dry yeast strains may be more limited in terms of variety but are excellent for beginners or when consistency is key.
Liquid yeast, on the other hand, offers a broader selection of strains, including rare and unique options that can impart distinctive flavours. However, it has a shorter shelf life and must be handled more carefully and may require a starter (more on which below).
Many experienced brewers will likely tell you that liquid yeast will yield better final results, while a few might tell you there is no discernible difference. For the most part, with either type, it comes down to a healthy and viable yeast population for that fermentation to go off without a hitch, and minimising the risk of under-pitching, which will lead to off-flavours in your beer.
On the face of it, dry yeasts are cheaper to buy — anywhere from $7-$10 for a packet compared to $20-$30 for a liquid yeast.
Froth Tech release new dry yeasts
New Zealand yeast provider Froth Tech says choosing wet or dry yeast depends on multiple factors.
“In Aotearoa some breweries use dry yeast to ferment their beers, some use liquid yeast, and some use both,” says Froth tech co-founder Simon Cooke.
“Some pitch in the right amount of yeast for a full brew, while some use a smaller tank to grow a small amount of yeast into the right amount first — known as a ‘yeast starter’. These choices faced by brewers are informed by cost, brew volumes and frequency, recipe and flavour profile considerations, whether the yeast will be re-pitched (re-used) in other brews or if it is just a one-off, dry-hopping practices, production scheduling, and product familiarity.
“Our three core dry yeast strains, Buddy (American Ale), Vape (Hazy / English Ale), and Sesh (German Lager) are contract-manufactured by an offshore producer in China with very strict quality controls. The dry yeast is vacuum packed into 500gm blocks, labelled, and shipped to Froth Tech headquarters in Lower Hutt, ready for distribution. Our dry yeast has a two-year shelf life, while liquid yeast has a 2-3 month shelf life.
“With liquid yeast, breweries will order in advance and brew with it as soon as it arrives by overnight courier, while with dry yeast they may order a whole case and grab a few packs out of the fridge as they need them. That flexibility can be really valuable to busy breweries with fast-change production schedules. We’ve received excellent feedback already from many of NZ’s most popular breweries, and chances are Pursuit of Hoppiness readers have likely sipped a beer made with Froth Tech dry yeast by now.”
Making your own yeast
A lot of the liquid yeasts on sale today come in ready-to-pitch form boasting 200 billion yeast cells to see your 20-litre batch of beer safely through fermentation to final gravity — doing away with the need to make a starter.
While this is all well and good for your first brew with that fresh new packet of liquid yeast, it’s important to realise those cells are good for multiple batches if you harvest them and re-use to make a starter — and the slurry at the bottom of the fermenter at the end of the process needn’t be tipped out and disposed with.
Careful harvesting of a few billion or so of the cells and storing them in anticipation of making a yeast starter for your next brew is recommended.
Recycling yeast in this way half a dozen times means your liquid yeast will end up more cost-effective than a once-and-done dry yeast in the long run.
Once you have kegged or bottled a batch of beer fermented with liquid yeast, you’ll be left with some yeast sediment (called “trub” and pronounced “troob”) at the bottom of the fermenter. Trub (a name derived from the German for “cloudy”) is a sludgy mix of yeast, protein, malt and other unfermentable materials that settle to the bottom of the brewing vessel.
The object is to separate the yeast from the other parts of the trub. To do this, carefully pour off any excess beer, then add some cooled boiled (or bottled) water and gently swirl the fermenter to suspend the yeast. Let the heavier particles in the trub settle for 20 or 30 minutes, then pour the yeasty liquid on top into a sanitised jar with a lid. Store this in a fridge until need to make a starter.
Making a yeast starter
The goal of the yeast starter is to create a small, nutrient-rich environment where the yeast can grow and multiply before pitching into fresh wort. To do this, you’ll need to make a starter wort. A typical ratio is 100g of dry malt extract (DME) per 1 litre of water. A sensible starter size for a 20l batch of beer could be anywhere between 1 and 2 litres.
Bring the water to a boil in a pan, add the DME (and yeast nutrients if you so wish), stir to dissolve and boil for 10-15 minutes. After boiling, cool the wort in an ice bath to room temperature (or below 75F/24C).
Once cooled, pour starter into a sanitised vessel, preferably a conical flask, leaving some space at the top, and cover with foil or pop in a bung and airlock. A magnetic stirrer plate is a great bit of kit to keep the solution in motion. If you don’t have a stirrer plate, you can swirl the vessel manually every few hours to keep the yeast in suspension.
The yeast will begin to multiply and ferment the sugars in the wort. You should notice some bubbling or a krausen (from the German for foam) forming, which is a sign of active fermentation. Don’t necessarily expect the airlock to bubble like it would when you are fermenting a batch of beer.
When it’s time to pitch the yeast on brew day, pour the yeast slurry directly into the fermenter containing your chilled wort.
A starter should be made 24-48 hours before you brew to ensure the yeast has time to grow but also remains fresh and healthy by brew day, so you’ll want to get it going a day or two before brew day.
A well-treated yeast should be good to re-use up to 10 times.