On yeast starters....

[hbrookie]

I get that we all want/need to 'proof' our yeasts. It's just good technique to make sure that our yeast is viable.

What I don't understand is why there are these tables to determine how many cells of yeast you need to throw in your brew. Sure you don't want to throw in way too few because there's always the possibility that there's something else lurking in there that could get hold before your yeast do, but I just did a lot of reading at howtobrew.com and 99% of what he's got out there makes perfect sense except his yeast starters.

At one point it's stated to make a mini wort and get it going for a day or two beforehand to make the yeast nice and healthy before adding to your brew. Now, anything funky the yeast are going to do in the first two days is in that starter. The same starter you're going to dump into the fermenter.... Thus funky went in the fermenter too.

I've also seen people say "not enough yeast and they get stressed out". I can understand that "not enough vitamins/minerals they may get stressed out" but to this day I have never seen a fat man looking all stressed out at an all you can eat buffet.

Also, yeast reproduce soooo rapidly that by the end of fermentation you have been thru several generations of yeast. Several of the statements about yeast on howtobrew.com appear to make assumptions that all of the yeast are in the same stage of their life cycle (something I find extremely hard to believe - someone's going to need to give me a reference if you can actually manipulate that one).

I guess what I'm asking here is "how much of our yeast handling is superstition and how much is science."

It seems that most of these issues can be handled by an extra day in the fermenter (which is fine since we say "leave it til it's done" anyway.

 

[DrunkleJon]

Good question. All, correct me if I am mistaken this is the internet after all. Yeast pitch rates do affect the final beer. I cannot quote you links to scientific studies about it, but I believe Revvy probably can.

At one point it's stated to make a mini wort and get it going for a day or two beforehand to make the yeast nice and healthy before adding to your brew. Now, anything funky the yeast are going to do in the first two days is in that starter. The same starter you're going to dump into the fermenter.... Thus funky went in the fermenter too.

Not necessarily, some pour off the resulting beer from the starter before pitching the stepped up yeast. Also, yeast starter wort is usually a lower gravity wort and oxygenated well to not stress the yeast. Not to mention that for a 5 gallon batch, even if throwing in the entire starter, you are throwing in at most 2 liters to 5 gallons which really would not be all that noticeable. Plus the stepped up happy yeast has time to clean up any flavors that result from the starter when cowing down on all the fresh wort you dumped it in.

Easiest way to know for certain though is to try it yourself on some experimental 1 gallon batches. Make up 3 gallons of wort, grab some s-05 or some other yeast and put a tiny amount in one gallon of wort, the proper amount as dictated by a pitching calculator in another and over pitch the heck out of the third. When they are all done taste them side by side. You will notice a lot more esters in the underpitched one, the properly pitched one will have some esters and probably be balanced, and the overpitched one will be rather clear of esters. This is one of the reasons why the pitching rate for lagers is so much higher than ales. In ales you want some of the esters that are caused by stressed due to underpitching/warmer temperatures, where lagers are intended to be clean and free of the ester-ey goodness.

I am not saying that you will not make good beer by underpitching, and yes it will take longer. It just will not be the beer it could have been.

Just my 2 cents. Take or leave them as you will. I did set them heads side up though.

 

[SC_Ryan]

The short answer is yes, the information on pitch rate is based in science. If you are interested in the science, read the book "Yeast" by Chris White and Jamil Zainasheff.

 

[gr8shandini]

I used to think the same way - the idea of an abundance of food being "stressful" is silly to me. However, if you think of it another way, it starts to make sense. In order to reproduce, the yeast are going to require more nutrients than just the sugars in the wort. This means that they may be using up proteins and such that are responsible for head retention and mouthfeel. It's also said that they produce more esters during that phase, but I haven't found that to be hugely noticeable.

I can't remember if it was a Brewstrong, or BYO article, or what, but they did an experiment splitting some wort and doing an underpitch (the equivalent of 1 vial or smack-pack) and one at the "book value" and having folks do a blind taste test. The result was interesting. Most of the respondents said the underpitched beer was "cleaner" and thinner while the properly pitched beer had more body. It was pretty much 50/50 as to which they preferred.

Me, I've tried both. Pitching at the proper rate is better for me, but the difference is small and I hate making starters. So, I either use dry yeast (S-04 or S-05 gets used in about 70% of my beers), or make a batch without a starter and use the yeast cake for a subsequent batch, or bigger beer. Yeah that "starter batch" isn't as good as it could be, but it's plenty drinkable.

 

[duboman]

Look at it in human terms and labor efficiency: if you hire a crew of two to do the work of 6 then the two you hired will be over worked and stressed out to complete the job properly. If you hire 10 then there is wasted motion and inefficiency.

In both cases the final product has the chance of not being completed properly due to the inefficient labor force.

If you grow the proper amount of healthy yeast to ferment an appropriate batch of beer then the final product has a greater chance of turning out the way it was intended. If you under/over pitch then the chances of something going wrong are greater.