Making a yeast starter is a worthwhile endeavor for any home brewer. Yeast starters are essentially used to increasing the number of yeast cells on hand before pitching them into your fermenter. This has three great benefits, it will tell you if your yeast is dead BEFORE you pitch it into your main batch, your resulting beer will taste better and it will ferment faster – all pretty worthwhile outcomes.
Pitching such a small number of yeast cells or unhealthy yeast cells can have a noticeably negative impact on your beer. Long lag times, stuck fermentation and slow carbonation are also some other common problems faced when using unhealthy, stressed yeast.
Yeast is a living thing after all. Treat them right and they’ll return the favour with a tasty drop.
To make a yeast starter you’ll need the following components:
- A large PET bottle (1.25L or 2L)
- Light dry malt extract (150g)
- Liquid yeast vial or smack pack
- Water (850ml)
Making the Starter Wort
It’s kind of like brewing a tiny batch of beer. Just add the dry malt extract to a saucepan with about 850ml of water and bring to the boil, stirring until the malt has dissolved. Once it boils, take the saucepan off the heat and let the wort cool to room temperature. I find the easiest way to do this is to partially submerge the saucepan in some icy water in the kitchen sink. Once it reaches 22c (optimal) pour the liquid into your cleaned and sanitized PET bottle (a cleaned and sterilized funnel makes this easy) and then congratulate yourself on making a top-notch starter wort.
Pitching the Yeast
If you’re using a smack pack, smack it as per the instructions, wait for it to swell, cut it open with some sanitized scissors and pour the yeast into the bottle. If you’re using a yeast vial, sanitise the vial, open and pour. Once the yeast has been introduced to the wort, loosely wrap the lid in some sanitized tin foil and you’re done.
Helping it Grow
For optimal yeast growth, keep it the starter away from excessive light and try and maintain it at constant room temperature or as close to 22c as possible. Oxygen is also essential for the yeast cells to replicate at an increased rate, to do that, simply give the bottle a quick swirl whenever you can. You will notice a dirty froth form on the top of the liquid after 6-12 hours, know as a krausen this foamy goodness is perfectly normal and in fact a great sign that your yeast is alive and kicking.
The starter will be pitch-ready in about 24 hours and will be perfectly useable up to 7 days after making it. So once you’re ready to use it, give the bottle a bit of a shake, ditch the foil and pour the whole thing directly into your fermenter. Happy days.