So Friday night I was all amped up to brew. I was all ready to head out the door to my in laws where I do my brewing (space and temp purposes) and I give the smack pack I nice, solid wallop. I guess I hit the thing too hard because I split the pack near the top of the package (about a one inch gash). Yeast sprayed all over my hand and kitchen floor. The vast majority of the contents were still in the package and I proceeded to google "broken yeast pack" or something to that effect. After some quick internet research and with my LHBS closed I taped the pack up and went about my business. The pack ended up expanding very slightly over the 3+ hours and I pitched. What are my chances of an infection? What are my chances of reaching full attentuation? Sorry for the long post and thanks in advance for any responses
OG and volume of wort along with the age of the pack would help determine how much you underpitched. I'd write to Wyeast about it and see if they offer some compensation. Personally if I were to hazard a guess based off the info you offered: Chance of Infection: <0.5% Chance of full attenuation: >75% Chance of off-flavours due to under pitching: >10%
yeast was 1056. OG was ~1.055 I didn't measure because it was extract. If definitely didn't get higher than 1.055 but could have gotten lower due to less burnoff on stovetop.
The volume of a standard smack pack is ~125 ml iirc, and it's set up to be pitchable to up to 1.060 wort, so assuming you loss about than 10% your pitching rate should be fine. Contamination should be an issue unless your hands were covered in grain dust and rubbed the inside of the pack. As long as the yeast was properly activated and happy, full attenuation should be no problem.
I can't say what your chances of infection are. I would probably have done the same thing you did in that situation, and yes, it will probably turn out fine. For the future, there are two ways to avoid a repeat of this: 1) Have a couple of packs of dry yeast on hand at all times for exactly this kind of situation. Safale US-05 is supposedly the same yeast strain as WY1056 even. And 2) make a starter in advance of brew day. Which brings me to my next point: Even if the pack was 100% viable (manufactured very recently) and there had been no yeast loss, you still underpitched. You should use the Yeast Pitching Rate Calculator at mrmalty.com to make sure you are pitching enough healthy yeast to produce the best possible beer. For five gallons of 1.055 wort you would have needed two very fresh Activator packs, or 1 pack and a 2 quart starter. You may well reach full attenuation, but that isn't the sole factor that determines how healthy your fermentation was.
I agree with this. The volume of the smack pack is irrelevant. The cell count of a fresh pack is roughly 100 billion cells. The idea that it's "fine" for use in 5 gallons of wort up to OG 1.060 is IMO advertizing hype from a manufacturer. I believe that rate to be underpitching, and that it will not make the best possible beer. You will now hear from someone that they have been making great beer for over 93 years pitching single smack packs. Caveat emptor.
The volume of the smack pack is 100% relevant. The yeast are suspended in the smack pack so if 50% of the liquid squeezed out, then he'd have lost 50% of the yeast. I like Jamil's pitching rate calculator as it is a very useful guide, but as someone that studies yeast biology and genetics as part of my PhD thesis, underpitching by 1 fold is not that big of an issue. Although 200 billion cells would be optimal for a 1.055 wort, with healthy yeast that will probably not make an appreciable difference. As long as the wort is properly oxygenated and the right temperature, the yeast needing to bud one more time to reach optimal density before fermentation starts is a minor concern. I think the measurable threshold is probably 1/3 or 1/4 of of the optimal pitching rate. I think this extent of underpitching and you'd probably be able to tell. there's this experiment on Underpitching: http://seanterrill.com/2010/05/09/yeast-pitching-rate-results/ And basically they found that underpitched beer tended to be more bitter and astringent, but even with about 25 Northern Brewer forum members getting a 3 samples (1 of the underpitched and 2 Control, or vice versa). The results showed that about half the brewers selected the adequately pitched beer as their favorite and 43% of them identified the one that was correctly pitched. Although with a small sample size it's hard to draw conclusions, I would say that the result seems to indicate that even when pitching 0.3 Billion versus 0.75 Billion cells/L * Plato, most people couldn't really tell the difference between under and overpitched or express a preference for one of the other. However, all that said, I think that it's probably always best to try to pitch the "correct" amount of healthy yeast you possibly can into your wort to ensure the best possible chance of success
Here's one experiment I just found: http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/ Note the comment from Garrett Oliver: IMHO, the OP already cut the optimal pitch rate by 50%, and probably much more when you factor in the viability of the yeast and whatever amount was lost. From my own experience I feel that I have noticed a marked improvement in my homebrew since I got religion about mrmalty.com and following the pitch rate advice.
It may have been relevant if he had measured the remaining volume. But he didn't measure, so how does knowing the normal full liquid volume help? Rather than argue this one for the 1000th time, I have an idea to collect some data via poll. Stand by.
