Wyeast Catalogue

Making a Starter

Posted by Neil Bamford, September 2nd, 2010 | 0 Comments

Starter Recipe:
The optimal media for cell growth and health require using a malt based media (DME) fortified with nutrients. Gravity should be kept near 1.040 and cultures should be grown at 70°F.

Recipe
1 cup DME (100g, 3.5oz)
½ tsp Wyeast Nutrient
1qt.(1L) H2O
Mix DME, nutrient, and water.
Boil 20 minutes to sterilize.
Pour into a sanitized flask or jar with loose lid or foil.
Allow to cool to 70°F.
Shake well and add yeast culture.

Timing of Starter:
Because starters are inoculated at high cell densities, growth is usually maximized within 24-36 hours. The gravity of the starter should always be checked prior to inoculation into wort to assure proper cell growth . Cultures should be used immediately, or refrigerated for up to 1 week before using. Cell viability will decrease rapidly if culture are left at ambient temperatures for extended time.

Stirring and O2:
Agitation aids in removing inhibitive CO2 from suspension as well as possibly adding small amounts of oxygen. Stirring or shaking the starter periodically or using a stir plate will improve cell growth. The use of stir plates has been shown to increase cell growth 25-50% over a non-stirred starter.
Small additions of oxygen periodically throughout the growth of a starter will replenish sterols and improve cell yield.

Caution: It is important to understand that creating a starter can increase the risk of infection by undesirable organisms. Small levels of contamination can multiply to unacceptable levels, causing undesirable effects on the finished product.

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