Making a yeast starter

If you're using liquid yeast, or if you're going to re-use yeast you've washed from a previous brew, you'll need to know how to make a yeast starter. A yeast starter is the process of growing your yeast cell numbers and getting them ready to do an effective job of fermenting your batch of wort.

Here's a link to billybrew.com which does a great job of describing the process.

Yeast washing

Yeast washing refers to the process of reusing the yeast from a just completed fermentation.

Once you've finished taking the fermented beer off your yeast cake (either after bottling or transferring to a secondary vessel), you're left with a thick trub consisting of healthy yeast, dead yeast, hop and grain particles.  Washing is the process of separating these out and keeping the healthy yeast, ready for re-using in your next brew.



This post on billybrew.com is the best explanation (with video) I've found.

Cultivating yeast from a bottle of beer

Propagating yeast from a bottle-conditioned beer is relatively easy. You'll need the following before you start:

• An unopened bottle of bottle-conditioned beer
• 100g of dry malt extract
• A lighter
• A 1.25 litre jar or jug
• Dry or liquid pack of yeast on hand as backup
• An airlock that can fit on a beer bottle
• An airlock that can fit on your starter jar lid

1. Five to Six days before your brew day, prepare 200ml of wort using 200ml water and 1 tablespoon of dry malt extract (you could probably also use dextrose or sugar as well).
2. Boil it for 10 mins then cool to about 25C. 
3. Carefully decant all but the last couple of centimetres of beer from your chosen bottle, leaving all the yeast behind.
4. Flame the top of the bottle to sanitize it. Then pour your 200ml of wort into the bottle, attach an airlock and agitate the bottle for 2-3 minutes to aerate it.
5. Store the bottle in a cool place with an even temperature of around 20C (a hot water cupboard is a good spot).
6. 2 - 3 days later, check that the culture is showing signs of activity. If it is, proceed.
7. Prepare a 1 litre starter using 75g of dry malt extract. Boil the wort for 10mins and let it cool to around 25C. Pour this into your starter jug or jar
8. Remove the airlock from the bottle, flame the top, swirl the bottle and then pour it into your starter jug/jar.
9. Attach the lid with airlock and agitate the jug/jar for about 2-3 minutes.
10. After about 2-3 days the fermentation should be active and ready to pitch into a 19 litre wort. Remove the airlock, flame the rim of the jug/jar.  Swirl the contents and pitch it into your wort.