this is a little old thread but exactly my probelm right now I'm doing a vienna lager extract kit. as i haven't had luck with starters, but dry yeast for ales have worked okay on the wort. My question is do you pitch the next day at mid 40's? I was going to pitch at 75 the day of the brewing, what do you guys think?
Many homebrewers have various means of pitching dry lager yeast and any of them will work. However, the most ideal way to pitch dry lager yeast is to cool the wort to fermentation temp (50°F-ish)... (or cool to slightly below fermentation temps and let it warm up slowly to fermentation temp), rehydrate two packs of dry lager yeast (per ~5 gallons) according to the manufacturer's recommendations and cool the slurry to close to the same temp as the wort, then pitch. Here's the answer to some FAQs:
Why rehydrate?
When dry yeast are exposed to a liquid, they don't initially have regulation over what they allow to pass through their cell membranes. Yeast need to excrete enzymes to break down some sugars (like maltose) before metabolizing it. If these sugars and other compounds are allowed to pass through their cell membrane unregulated, the yeast can't deal with them and the yeast cell dies. So, in short, pitching dry yeast onto wort kills some of the yeast cells and reduces the pitch rate.
The less yeast that are pitched, the more yeast growth is required and the more flavor-active compounds (like esters) are formed. This is usually OK or not noticeable in most ales, which are expected to be more flavorful and typically have more hop bitterness and complexity which masks some of these flavors. But in lagers, a clean taste is typically desired and you want to pitch a lot of viable yeast to reduce the need for yeast growth and the production of flavor-active compounds.
Why cool the wort so much before pitching?
Lagers are usually fermented in the upper 40s°F to the low 50s°F. Lager yeast, when allowed to ferment in warmer temperatures, will produce more flavor-active compounds similar to above. Some yeast cells begin to ferment very soon after being pitched (even before fermentation "takes off"). If you pitch lager yeast at a warmer temperature, they will start fermentation warm and produce esters, diacetyl, fusel alcohols, etc.
The disclaimer to the whole thing is that some lager hombrewers don't do one or both of the above and still produce good beer. So, whatever you decide to do, at least you know the potential outcomes.
