Why and How to make a Yeast Starter

 The Starter is a technique that allows you to multiply the amount of yeast cells in a small volume of wort and is done to obtain the right amount of active cells that will start the fermentation of our beer. Here you will find a step-by-step guide for the preparation of a Starter that does not require special tools for its realization. 


Making a starter is not always necessary, but it is highly recommended if:

• Initial density is greater than 1,050;

• Yeast has passed its "best before" date;

• Yeast is close to the date “to be consumed preferably by” and we want to have a lighter heart;

• Packaging has not been stored in the most suitable way;

• You want to ferment lager yeasts at temperatures below 18 °C;

• A faster start of fermentation is desired.


Generally, 0.5-1 liter of Starter is required for the fermentation of 20-23 liters of wort, but there is a question you must ask yourself before starting: why do you need the Starter?

Based on the response, and therefore on the needs of the individual batch, for 20 liters of wort you generally have to consider these recommendations:

• OG equal to and less than 1.048: no Starter

• OG between 1.050-1.065: 0.5 liters of Starter

• OG above 1.065: 2 liters of Starter

• Near or past expiry date: 1 liter of Starter

• Fermentation of lager yeasts with inoculation at 18-20 °C and fermentation at 8-12 °C: 1-2 liters of Starter

• Fermentation of lager yeasts with inoculation at 10-13 °C and fermentation at 8-12 °C: 2-4 liters of Starter.


To prepare a half liter Starter proceed as follows:

1) Prepare the yeast pack by bringing it to room temperature. If you have stored the yeast in the fridge, take it out a couple of hours before you start and let it come to room temperature.

2) In a clean and dry flask pour about 300 ml of water. Add 60 g of Dry malt extract or 75 g of Liquid extract malt and shake / mix well. Add water several times until you reach a little less than 500 ml of total volume (considering that to reach 500 ml you will need to add the yeast). Shake well with each addition to help dissolve the extract (dissolving the extract in cold water will make it much fewer lumps and make the process much easier and faster).

3) Boil the mixture for 5-10 minutes. This way the wort will be sterilized. The advantage of using a flask is that it is not important to sanitize it first, as it will sanitize itself by boiling.

4) Cool the wort until it reaches room temperature (about 20 °C). If you use a flask, cover it with sanitized aluminum foil and let it cool naturally, as immersing it in water would cause it to break.
The resulting wort should have an initial density of about 1.040. This OG is essential to promote only the reproduction of yeast and avoid the tumultuous phase of fermentation and the consequent formation of alcohol. Alcohol is in fact harmful to cells with high concentrations of yeast as in the Starter.

5) If you have not prepared the wort directly in a flask, at this point pour it into a sterile glass container, such as a sanitized bottle. Skip this step if you used a flask.

6) Sanitize the yeast package, shake it and pour it into the must.

7) Cover the top of the container with a sanitized piece of aluminum that still allows the CO2 to escape, or with a cap with a bubbler.

8) Shake vigorously to oxygenate the compound as much as possible. If you use a flask, be careful.

9) Let the yeast cells reproduce for 24-48 hours at room temperature (18-20 °C). You will not see any visible activity, although the yeast is actually busy consuming the oxygen and sugars in the solution to grow the new cells.

10) When the yeast has completed its reproductive activity, pour the half liter of Starter into the fermenter. If you made 1 liter or more of Starter instead, read on.

If you want to make a starter but don't have time to make it, find out what you can do! Click here


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