Home Brewing Beer How to Make a Yeast Starter for Optimal Wort Fermentation

Home brewing beer is more successful if fermentation is conducted with healthy yeast from a yeast starter. The yeast population can also be grown to an optimal quantity. This allows the yeast to complete the fermentation without undue stress, producing the desired beer appearance, aroma, flavor and body. Making a starter brings your yeast to optimum health and increases the yeast population to an appropriate level.1. Components for the starterYou will need a Pyrex or Bomex Erlenmeyer flask or a glass jug the size of your starter, plus some head space room. You will need dry malt extract (DME), a liquid yeast vial or pack, yeast nutrient and water.2. Making the starter wortThe starter wort is just like a mini batch of beer. Put the DME into the flask or an appropriate size pot if using a jar to make the starter. Add water to the desired volume and a pinch of yeast nutrient. Stir to dissolve the DME. Put the flask or pot onto the stove and gently boil for 15 minutes. Cover the pot or flask with a sanitized lid or aluminum foil, then cool the starter wort in an ice water bath until it is room temperature. If using a jug instead of a flask, sanitize the jug, then with sanitary technique transfer the cool wort to the jug.3. Aerate the wortThe yeast will grow much better if they are supplied with oxygen. One way is to vigorously and frequently shake the yeast starter. Other methods that may provide better oxygenation are using an air stone with an aquarium pump, using a diffusion stone with pure oxygen or using a stir plate.4. Pitching the yeast into the starterSanitize the top of the vial or pack of yeast. Also sanitize the scissors used to open the pack. Suspend the yeast in the vial or pack by gently shaking. Pressure may build up in the vial when shaking, so just crack open the lid and reseal a few times to relieve the pressure. Using sanitary procedure, transfer all of the contents of the vial or pack to the starter flask or jug. Cover the container with sanitized aluminum foil.5. Allow the starter to growProtect the starter from excessive light. Keep it at room temperature and prevent temperature swings as much as possible. Allow it to complete its growth cycle for about 48 hours. If the starter is relatively small, no more than 5% of the intended batch size, it can be pitched while still active at about 18 to 24 hours, directly into the full batch. If it is larger, it is best to let the growth phase complete in 48 hours, chill the wort in the refrigerator for at least 24 hours, decant most of the spent starter liquid and pitch just the yeast slurry with a little of the liquid into the full batch.Using a yeast starter is a key technique in making better beer. It most importantly optimizes the health of the yeast, as well as grows them to sufficient numbers to ferment a beer with appropriate appearance, aroma, flavor and body. This will increase your success and enjoyment of home brewing beer.