Experimenting with Yeast Starters for Dry Yeast

[Woldemar]

As a fairly new homebrewer (6 months), I recently decided I would experiment with simple DME yeast starters for my dry yeast. Specfically, I made one started for a 5 gallon batch of an organic California Lager fermented with Saflager S-23 and one for a 5 gallon batch of strong Belgian Pale Ale fermented with Safbrew T-58. I suppose I shouldn't be surprised that the fermentations took off like a bat outta hell, but they were so rigorous that active, airlock-visible fermentation lasted all of 36 hours! I've given the California Lager about 5 more days of "secondary" time and it's within the target final gravity range (about 1.016). The Belgian Pale only recently ceased displaying visible signs of fermentations, but was a decent amount outside of the target gravity range. I added some yeast energizer this morning, and, within 5 minutes, a slow but steady rate of visible airlock activity has resumed. I guess my question is this - I've read a fair amount about the pros and cons, advisements and warnings, when it comes to pitching that much yeast, but what are the consequences in terms of flavor and overall beer quality? Should I be doing anything to compensate for the short active fermentation period?

Thanks in advance for your help!

-Michael (brewing with dry yeast only and converting mass-marketed beer drinkers one by one - in Korea!)

 

[Rick500]

It's a neat experiment, but starters aren't needed for dry yeast. And it's actually cheaper to buy whatever quantity of dry yeast you need to pitch for a given batch, than it is to use DME to make starters for them. (Or it is in the U.S., I should say. Not sure about Korea.)

To answer your question, though, overpitching (while IMO better than underpitching) will result in all those yeast using up all the available sugars before they get through a complete growth cycle, which means that by the end of fermentation you'll have a bunch of low-viability yeast cells, unable to clean up their metabolic byproducts like healthy yeast would.

Here's some more info, from mrmalty.com: "You might ask why not pitch as much yeast as possible? There is also an upper limit to how much yeast you should add. Logsdon says, “I try to stay within 20% of my ideal pitch rate and I prefer to slightly under pitch rather than over pitch. This causes more cell growth, more esters, and better yeast health. Over pitching causes other problems with beer flavor, such as a lack of esters. Changes in the flavor profile are noticeable when the pitch rates are as little as 20% over the recommended amount."

 

[stoutaholic]

Also, sometimes you WANT yeast by-products, such as in a wheat beer or certain Belgians where there is a characteristic extery flavor that is required by the style.

Yeast metabolism produces by-products. The more yeast growth that occurs, the more by-products, such as esters, fusel alcohols, aldehydes, and vicinal-diketones (diacetyl) that are generated.

As Rick pointed out, over-pitching will MINIMIZE yeast growth. The metabolism of all those yeast cells will consume the fermentable sugars before significant amounts of yeast growth and reproduction can occur. If yeast growth is minimized, then clearly the by-products produced by yeast growth will be minimized.

So at least ONE of the consequences of overpitching is a REDUCTION in yeast metabolic by-products (thus a reduction in those by-products that are desirable for some styles of beer).

As to the point of low-viability yeast being unable to clean-up any remaining byproducts at the end of fermentation -- I haven't heard of that, but that is an interesting idea. If anyone has more information on that, I would definitely be interested to read about it. There are probably some other disadvantages of over-pitching as well. Some author suggested that a characteristic "yeast bite" will result in the flavor of the beer, but I haven't heard that elsewhere, and am not sure if he is just talking about the flavor that would result from lots of yeast being suspended in the final product. If so, then this could be prevented by filtering or fining the beer to remove the excess yeast.

 

[samc]

My one experience with over pitching yeast resulted in a very alcohol tasting beer. After a few weeks that went away and the beer was excellent. Similar batches made using the correct amount of yeast resulted in excellent beer from day one! Nothing scientific, just the facts.

 

[Woldemar]

Thank you, everyone, for your informative and helpful responses. It was an interesting experiment, but I will go back to the ways of simple rehydration!

A semi-related question - could an over-abundance of yeast result in much slower clarification of the beer? The aforementioned strong Belgian Pale Ale has ceased its second burst of fermentation, and is now within the target final gravity range. The problem is that it's not clearing up. I did one racking, and noticed that this yeast strain has some green color to it - could the amount of yeast that resulted from the use of a starter also significantly prolong the clarification process? The temperature has also crept up to 76 F, but I am bringing it back down to about 66 F.

Thanks again. Nazdravi!