Well with the weather really cooling off down here in Tasmania its time to start making some real lagers. A lager is a beer where only a very small part of the flavour profile is attributed to the yeast.
Lager are crisp and clean to taste with the majority of macro breweries producing beer in a lager style (I say style as not all use a true lager yeast). Lager yeasts have been selected over many years to perform well at cool temperatures. A typical lager ferment will occur at between 9-13 degree C while an ale is higher at around 17-21 degree C.
The yeast I have chosen for this brew is Wyeast 2278 Czech Pilsner. These yeast come in a smack pack that is enough for one brew however I split my smack packs to reduce the cost of yeast per brew. This then requires me to make a starter to build up the number of yeast cells required for a healthy ferment.
When I split my yeast I store them in 50ml centrifuge tubes under boiled then cooled water in the fridge. Always ensure to label with yeast strain and the date that it was split.
This small amount of yeast is then grown up into the desired volume usually 4L over 3 steps. The following is a list of item you will require to make a yeast starter.
- Carboy 5L
- Pouring jug approx. 2L
- Light dry malt extract (LDME) or unhopped wort
- Spoon
- Scales
- Aluminium foil
Select the yeast you wish to you use for your brew and remove from fridge. You want the yeast to warm a little before adding it to the starter liquid to reduce the thermal shock as this can damage the yeast.
Sanitise everything that will come into contact with the yeast if you are unsure sanitise it cleanliness is key to the brewing process and yeast culture is no exception. I use Starsan it is a very popular choice among home brewers it is relatively cheap and the mixing rate is great only 1ml/L other sanitisers appear cheaper but need to be used in much higher concentrations that counteract any saving.
We will in essence be making a little beer for the yeast to grow in. So if you have some sterile wort (unhopped) from a previous brew this can be used. The typical gravity we aim for in a yeast starter is 1.035- 1.040 this gravity provides enough sugars to the yeast for growth without stressing them in a high sugar environment. To achieve this gravity with LDME we use 100g/L.
Your starter will be fed over a couple of days adding more wort each day to ensure an extended growth phase. I typically use the following steps.
Initial size 1L
24 hours add 1L for a total of 2L
48 hours ad 2L for total of 4L
96 hours refrigerate
Measure out your LDME and add water mix thoughly again ensuring anything touching the mix is sanitised. Add this mix to your carboy and add your yeast. Make up to 1L and cover opening with aluminium foil and shake well. Oxygen is required in the growth phase so a shake every few hours will encourage a health yeast and produce many more cells than if left still. A stir plate can be use to give continuos agitation and a higher growth rate again.
Each day measure the desired amount of wort for the next step, paying attention to your sanitation as you go. After 96 hours place the whole starter in the fridge to encourage the yeast to drop out of solution and become concentrated at the bottom of the carboy ready to be pitched onto your beer.
Using a yeast started does involve some prior planning before a brew day however the little effort it does takes can save you some money and allow you to keep a wide range of yeast on hand at all times.
If you have any questions please feel free to put them in the comments below.
When the starter is to be used used remove from the fridge and decant the liquid from the top of the yeast portion. Allow the yeast to warm to ferment temp and then it is ready to add to your brew.
