This week we continue our discussion on yeast with the process of creating a starter. A starter is useful to ensure that you build up your yeast cell count for higher gravity beers or your yeast viability is not at its best.
Starters with dried or liquid yeast: Most manufacturers will have a specific process for the propagation of yeast using a starter method below is the basic instructions for making a starter for a brew.
Items you will need:
- 2000 ml (67 fl oz) or greater borosilicate glass Erlenmeyer flask
- Larger container for water bath
- Tap Water 2000 ml (67 fl oz)
- Stir plate
- Magnetic stir bar (pill shaped 4 – 6 cm long)
- Dextrose (DME) 200 g
- Yeast nutrient
- Aluminium foil
- Sanitise all equipment.
- Add DME to the flask and make up to 2000 ml (67 fl oz)with water.
- Flask can be heated directly on the stove, boil gently for 10 mins.
- Add 1/8 teaspoon of yeast nutrient slowly to avoid boil over and continue to boil for 5 mins at the end of the boil add sanitised stir bar.
- Loosely cover top of the flask with aluminium foil. CAUTION FLASK AND CONTENTS WILL BE HOT transfer flask to water bath of cool water to cool to 25°C (77°F) for ales and 18°C (64°F) for lagers.
- For dry yeast rehydrate first then add to flask. For liquid yeast allow yeast to warm to room temperature. If using Wyeast follow the instructions on the package. Sanitise the outside of the package before opening and transferring the yeast to the cooled starter. Re-cover with sanitised aluminium foil.
- Place flask on stir plate and set to stir slowly stir the starter. This process can be done without stir bar and stir plate by gently swirling the starter every few hours maintain starter temperature and allow the yeast to consume the starter most yeasts will reach the correct cell density in 12-18 hours.
- Stop stirring (remove stir bar if possible with magnet) and allow the yeast to settle over the next 6 – 12 hours.
- Decant as much of the liquid off the top of the yeast as possible without losing any yeast.
- Swirl the last of the starter and yeast to make a slurry and pitch into the fermenter (be careful not to lose your stir bar if not removed) trying to keep the fermenter and the yeast starter covered as much as possible.