Yeast Handling — Pitch, Recycle, Repitch

Yeast is the only living ingredient in beer, and treating it well is most of what separates a clean fermentation from a sluggish or off one. The good news: modern dry yeast is robust, stable, and simple to use well. This guide covers pitching dry yeast, storing it, and harvesting and repitching a strain to brew the same beer for a fraction of the yeast cost.

How much to pitch

The headline mistake is overpitching because a liquid-yeast pitch calculator told you to. Those tools assume liquid yeast and overestimate dry yeast by 3–6×.

For dry yeast, weigh it: 0.5–1.0 g/L. For a typical 20–23 L ale that’s about 11–23 g (one or two standard 11 g sachets) — not the 30–60 g a liquid calculator suggests. Weigh by weight; no cell counting needed, because dry yeast viability is consistent and known.

Pitch rate still shapes flavour: underpitching stresses the yeast (more esters, fusels, slow start); heavy overpitching gives a faster, cleaner, less expressive ferment. For most ales, one well-stored sachet at the right temperature is the no-drama default.

Sprinkle or rehydrate?

For modern Lallemand/Fermentis dry strains, sprinkling dry onto the wort is the preferred method — it performs as well as rehydration for most beers:

1. Sanitise the scissors and the top of the pack.
2. Sprinkle the yeast evenly over the wort surface as the fermenter fills.
3. The motion of filling mixes it in — no stirring needed. Don’t submerge the sachet.

Rehydrate instead when the wort is stressful for yeast:

• High gravity (above ~1.065) — more osmotic stress; rehydration helps.
• Soured / low-pH wort — rehydration buffers the shock.

If you rehydrate: sprinkle the yeast onto 10× its weight of clean ~30–35 °C water (e.g. 11 g → 110 mL), leave 15 minutes undisturbed, stir gently, then step the temperature down toward the wort in stages so the slurry is within 10 °C of the wort before pitching. Never use distilled/RO water, and never let it cool slowly on its own — both cost viability.

Oxygen: first pitch vs repitch

This catches people out:

• First pitch of dry yeast — do NOT aerate the wort. Dry yeast is grown under high oxygen and packed with the sterol and fatty-acid reserves it needs. (The splashing at transfer in the walkthrough is plenty.)
• Repitched (slurry) yeast — DO aerate, to 8–10 ppm dissolved oxygen (>10 ppm for high-gravity wort). Harvested yeast has spent its reserves and needs oxygen to rebuild.
• High-gravity wort, even on a first pitch — some oxygen helps; or pitch more.

Storing packs

Keep a spare sachet in the fridge as a stuck-fermentation rescue — dry yeast’s shelf stability means you can always have backup on hand without planning ahead.

Harvesting and repitching

Repitching a harvested strain cuts cost per brew dramatically, and dry yeast is a great base for it because generation one is always a known, clean starting point. Only bother for strains you brew regularly (e.g. a house workhorse).

Harvest the healthy fraction:

• Promote flocculation with adequate calcium (50–150 ppm) in the mash.
• If using a conical/cone fermenter, dump the first dark slurry (early flocculators and trub), then harvest the creamy, light-brown middle of the cone within ~24 h of reaching terminal gravity. Avoid the top (slow, mutated cells).

Store it: chill rapidly to 4 °C, in a sanitised vessel, minimal air, and use within about a week.

Repitch it: aerate the wort (see above), and add a yeast nutrient — the benefit grows from about generation 4 onward. Keep simple records: strain, generation, source batch, and how it fermented.

Never repitch from these

Yeast harvested from these beers is too stressed or contaminated to trust:

• Any sour beer — never.
• High gravity (>8% ABV).
• Heavily hopped (>60 IBU) or heavily dry-hopped beers — hop compounds degrade yeast vitality.

After several generations, bacteria and wild yeast slowly accumulate; refresh from a new pack periodically rather than chasing a strain forever.

Quick reference