Imagine the most tired you’ve ever been. Perhaps it was after a long bike ride in the mountains, while changing planes en route from Dubai to Dulles, or the morning after a long evening spent hatching plans with friends over copious amounts of homebrew. Regardless of how you got there, your body probably loudly and clearly demanded a few things of you. Food, water, and nutrition are critical to our survival, and the same is true for yeast.
Yes, yeasts, those amazing little critters that transform wort into beer, require certain things in order to do their jobs. Like people, they simply perform better when they have optimal nutrition. Fortunately for them (and, indirectly, for us), wort offers a smorgasbord of delights that yeast just can’t resist. All-malt wort contains the following parts of a complete breakfast for your yeast:
- Sugar
- Nitrogen
- Vitamins
- Phosphorous
- Trace metal
Whether you brew from grain or from malt extract, you can rest assured that these critical components are already in there.
Note, however, that wort does not contain two essential elements: oxygen and zinc. Oxygen is most easily taken care of during the aeration or oxygenation process that you execute when the wort is en route from kettle to fermentor. Whether you use a diffusion stone and pure oxygen or simply splash with fervor, there’s no reason not to ensure adequate oxygen levels.
As for zinc, the amount actually needed is so small that weighing it out at home isn’t very practical. We’re talking only half a milligram of zinc chloride or zinc sulfate per liter of wort, which works out to one hundredth of a gram (0.01 g) for a 5-gallon (19-liter) batch. Unless you’re a chemist, a jeweler, or a dealer of contraband, you’re unlikely to possess a milligram scale. Nor do you need to.
There are a few commercially available products you can use to give your yeast an extra boost of nutrition. Most homebrew supply stores sell at least one of them. Wyeast Brewer's Choice, Wyeast Beer Nutrient Blend, and White Labs Servomyces are excellent products that deliver vitamins, minerals, trace metals and, yes, zinc. Not much is needed, just half a teaspoon of the Wyeast blend or one capsule of Servomyces added to the kettle near the end of the boil will get your yeast feeling the love. German beer nerds, take note: Servomyces is Reinheitsgebot-compliant. And you can use Wyeast Brewer's Choice in yeast starters in addition to your wort.
Between your all-malt wort, good oxygenation, and a little nutritional supplementation, your yeast will have everything it needs. And you'll be rewarded with better homebrew for it.