Starter?

[RosssBrew]

As an engineer (and a new brewer) I'm trying to understand the chemistry behind yeast. I'm assuming a started just increases cell count. That would lead to less time in the primary stage, because the fermentation should be quicker. If I don't mind having my primary take a couple extra days, why should I spend the time creating a starter? Does this effect flavor or ABV? Thanks in advance.

 

[Battles4Seattle]

If you do not pinch the appropriate cell count you can overstress the yeast which can cause off flavors. It can stall fermentation meaning it will finish too sweet. Yeast is finicky so it needs several things to perform it's job well, cell count, appropriate temperature, and the right sugar to convert which largely has to do with what temperature you mash at.

 

[619Brewer]

http://www.whitelabs.com/


Great resource and also if you're in San Diego area, you can go in and talk to them and they'll teach you more than you'll ever want to know about yeast.

I'm no expert, but you're close but the premise behind a starter isn't so much that you want a faster fermentation but that you want to have enough healthy yeast cells to tackle a larger gravity beer mitigating some of the risk of a stalled fermentation or stressing out the yeast which can create off flavors and byproducts that are undesirable.

Having, happy, healthy yeast is a massively important part of producing a good product.

 

[kh54s10]

It is not the time that "primary" takes. It is how the yeast work. If you underpitch the yeast must reproduce first then ferment the beer. This stage can produce off flavors. The best situation is to make a properly sized starter for the gravity of the beer you are brewing. The yeast can then immediately start fermentation. This will produce the optimum results from the yeast and hopefully a great beer.

 

[JuanMoore]

Yeast sex can give off funky flavors, especially if they have to do a lot of it to get the cell count high enough to start fermentation. Let them have the orgy in the starter, and leave the yeast sex flavors out of your beer.

 

[RosssBrew]

Yeast sex can give off funky flavors, especially if they have to do a lot of it to get the cell count high enough to start fermentation. Let them have the orgy in the starter, and leave the yeast sex flavors out of your beer.

Good point and fantastic analogy! I now understand under-pitching. Is there a problem with over-pitching?

 

[JuanMoore]

Good point and fantastic analogy! I now understand under-pitching. Is there a problem with over-pitching?

Supposedly yes, but it's so hard to do that it's not really worth worrying about.

 

[CA_Mouse]

Good point and fantastic analogy! I now understand under-pitching. Is there a problem with over-pitching?

Sometimes over pitching is desired. Belgian yeast will give banana flavors if pitched slightly low and clove if over pitched. I pitched twice the starter that I normally would for the clove notes in my Belgian Golden Rye (recent Silver Medal winner).

 

[Culbetron]

Overpitching can very negatively affect your beer. A yeast growth stage is very important in the fermentation process. Those Whitelabs peeps will tell you not to overpitch yeast (and they actually sell the stuff!)

 

[RM-MN]

Here's an experiment a guy did on pitching rates and their effect on the finished beer. Please note that his overpitch was more than 5 times the recommended amount and the underpitch was about 1/8 the proper pitch. http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/

 

[Culbetron]

Here's an experiment a guy did on pitching rates and their effect on the finished beer. Please note that his overpitch was more than 5 times the recommended amount and the underpitch was about 1/8 the proper pitch. http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/

Thanks for posting that. It was really interesting. I just happened to listen to Jamil talk about this same issue on his Eisbock show. Overpitching leads to dull, bland beers.