Can you pitch too much yeast (within reason)? In other words say you are brewing an average gravity ale and you would typically pitch one pouch of yeast. Is there any reason (other than cost) not to just go ahead and pitch 2 pouches to make sure you have plenty of viable yeast? Are there any downsides to doing this?
It's possible to pitch too much yeast. But the potential penalties for overpitching are generally more benign than the potential penalties for underpitching. If by "pouch" you mean a nominally 100B cell liquid yeast pack from White Labs or Wyeast, that's IMO going to be underpitching for most 5 gallon worts. Even White Labs has started moving away from their dumbed down one-size-fits-all approach, as evidenced by their new-ish pitch rate recommendation chart: My own advice would be... for ales, shoot for 750,000 cells per ml per degree plato, unless you have a stylistic reason to pitch more or less. One of the yeast calculators could be helpful here. Or use the White Labs' chart. For mid-gravity ales, it amounts to the same thing.
I am actually in the process of buying a stir plate and Erlenmeyer flask and plan on doing a yeast starter for the first time. That is why I was asking. I have messed around with the pitch rate calculators and would rather err on the side of too much, than too little. So, if too much (again, within reason) does not have any "serious" negatives, I will go with that approach. Thanks.
My guess is that some folks will opine that more is 'better' than less. Having stated the above I will personally 'underpitch' for certain yeast strains/beer styles. We all get to choose. Cheers! P.S. Beyond the consideration of yeast cell counts it would be wise to ensure proper oxygenation, proper yeast nutrition,...
How can anyone estimate with any useful precision the number of yeast anywhere without doing a microscope-assisted look-see? Serious question.
The key word is estimate. Start with the manufacturer's claimed number of cells. Adjust for age related viabilty. And if making a starter, use a calculator that uses widely accepted growth curves. There are lots of things in brewing that we don't know precisely. But an informed estimate beats a blind guess.
Yes, without a starter you are blind as to the health of the yeast. The number one reason to make a starter is to insure good yeast health. Secondary reason is to increase quantity. While you're at it (starter'ing) it's simple to boost the quantity to the level needed. When done correctly a starter tells you that the little buggers are healthy and ready to go to work and with a little bit of cunning you can optimize the quantity. Both of these factors measurably decrease lag time. In an extreme case it can save a brew (I've had DOA yeast, discovered when they wouldn't "start"). Stir plates are nice, but you can do an acceptable job with any large enough glass container and some wrist action. Overpitching can result in under-attenuation, low yeast esters, yeast autolysis favors, and poor head retention: White/Zainasheff
