Choosing between dry and liquid lager yeast

Lager yeast needs more cells

Lager yeast ferments cold, around 8 to 13 °C. It works more slowly in the cold. To compensate, brewers pitch about twice as many cells as for an ale. A common target is 1.5 million cells per millilitre per degree Plato.

For a 20 litre batch at 12 °P that works out at about 360 billion cells. Hold on to that number, because it decides most of what follows. Our guide to ale versus lager yeast explains why the two behave so differently.

Dry lager yeast is the easy route

Dry yeast is dried under controlled conditions and packed in sealed sachets, usually 11.5 g. Manufacturers of dry lager strains commonly recommend around 80 to 120 g per hectolitre for cold fermentation. For 20 litres that is 16 to 24 g, or two sachets. That is far less fuss than building a starter.

The advantages for an Indian homebrewer are practical:

• It keeps for a long time in the fridge and tolerates a few days at room temperature far better than liquid yeast.
• It ships without a cold pack through 35 °C summers.
• You pitch a predictable number of cells from a weighed amount.

Rehydrate it in sterile water at the temperature the maker suggests before pitching, or follow the maker's direct pitch advice. Our guide to rehydrating dry yeast covers the method. The best known dry lager strain, W-34/70, traces back to Weihenstephan in Germany and makes a clean, malty lager.

Liquid lager yeast offers more choice

Liquid yeast comes from labs as a live culture in a pouch or vial. The catalogue is far wider than dry: Czech, Bavarian, Danish, Mexican style and many more strains, each with its own sulphur, malt and ester profile. If you want to brew a specific regional lager, liquid often has the strain.

The catch is cell count. A fresh pack usually holds around 100 billion cells when fresh and fewer as it ages. Reaching 360 billion means three or four packs, or one pack grown up in a starter of 2 litres or more with a stir plate. That is a day or two of extra work before brew day.

The Indian problem: shipping and storage

Liquid yeast is perishable. Every day above refrigerator temperature costs viability. A pack that sat in a courier hub at 35 °C may arrive with a fraction of its labelled cells. Many Indian homebrewers order liquid yeast only in winter, or ask for cold packs and express delivery. Dry yeast removes most of that worry.

Cold fermentation is the second problem. Lager needs 8 to 13 °C for one to three weeks, then a cold rest near 0 °C. In most Indian homes that means a spare fridge with a temperature controller. The yeast choice matters less than having that fridge. If you do not have one, look at fermenting lager yeast at ale temperatures before buying any yeast.

Repitching changes the sums

One sachet economy that homebrewers like is repitching. After the first lager ferments out, the yeast cake at the bottom of the fermenter holds far more cells than you pitched. A portion of that slurry, collected cleanly and kept cold, can pitch the next batch within a week or two.

That works with dry and liquid yeast alike, which narrows the cost gap. A liquid strain bought once and reused for three or four batches costs less per batch than fresh dry yeast every time. The limits are hygiene and freshness. Slurry stored for weeks in a fridge loses viability. Any infection carries forward into every batch it touches. Keep a note of the generation number on the jar and start fresh after a few rounds, or sooner if fermentations slow down or flavours drift.

Which should you choose

For a first lager, we would choose dry. Two sachets, rehydrated properly and pitched into well aerated wort at 10 °C, give a clean, reliable fermentation with no starter and no cold chain worry. The flavour difference between a good dry strain and a liquid one is smaller than most beginners expect. It is much smaller than the difference temperature control makes.

Move to liquid once your process is steady and you want a particular character: the soft roundness of a Czech pale lager or the dry crispness of a north German Pilsner. At that point the starter is worth the effort because the strain is the reason you are brewing.

What separates a good lager from a passable one

Whichever you pick, the same things decide the result: enough healthy cells, enough oxygen at pitching, a steady cold fermentation, a diacetyl rest near the end and patient cold conditioning. Lager rewards brewers who understand what yeast is doing at each stage. That is where the science behind fermentation pays off in the glass.

Your first step: check whether you can hold 10 °C steadily for two weeks. If you can, buy two sachets of a dry lager strain for your first batch.

Common questions

How many sachets of dry lager yeast for 20 litres?

Usually two 11.5 g sachets for a 20 litre batch at normal strength. Manufacturers commonly recommend around 80 to 120 g per hectolitre for cold fermentation.

Can I pitch one pack of liquid lager yeast into 20 litres?

One fresh pack is well short of a full lager pitch. Use three or four packs or grow one up in a starter of 2 litres or more.

Is dry lager yeast worse than liquid?

No. Good dry lager strains make clean, well regarded lagers. Liquid yeast mainly offers a wider choice of strains.