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Why do 1 gallon kits say to only use half the yeast

Reading the directions for the recipes, they say use only half of the yeast and throw away the rest “and do not use it to make beer.”

1.) Do those packets of yeast just contain too many for a small 1 gallon batch?
2.) Why couldn’t you use the left overs to make beer?

One 11 gram pack of dry yeast is usually sufficient for 5 gallons of 1.064 OG beer. Pitching the entire pack for 1 gallon would be sever over pitching. Over pitching by a high amount can cause off flavors, or not the typical flavors of the yeast , to be produced.

The remaining yeast can be reused if you can keep the yeast dry and protected from contamination. A vacuum sealer works well for saving the remaining yeast. There is still risk though. The amount of risk you wish to take is up to you. Basically it is the cost of new yeast vs. the cost of ingredients for the next 1 gallon brew.

Well now Flars, I’m curious, would you then dump out the packet on a sensitive scale, weigh it, take half to rehydrate and pitch, while the other could go into a small sealable container for use later, without worries of contamination? Sneezles61

I would just get all the yeast evenly spread across the bottom of the package, pinch it in the middle and pour the estimated half. What remains in the pack would still be more than needed for a second one gallon brew.

Using a second container would risk contamination or wet the yeast especially if you use Star San as a sanitizer. Manufacturers suggest using the saved yeast within seven days, but I think it could be stored longer if it is kept dry.

Good info, thanks Flars!

As you take notes on your brewing process, consider including which half of the yeast packet you used. It may be useful information if you have to troubleshoot a batch that didn’t go well.

So I have a question related to over pitching, I am brewing my first extract 1 gallon kit, (Bavarian Hefeweizen) and my approximate half of the 11.5 gram yeast container was actually closer 7 grams instead of 5.75 grams. I weighed the excess on my scale.

Reading the above comments about 11g being used for 5 gallons, shouldn’t we instead be using like 1/5th of the 11g packet? It would seem half would constitute over pitching as it is.

Yea your concern makes sense. I was brewing kits from another company that used much smaller packets of yeast, hence my question.

I finally got my new Northern Brewer 1 Gal kits in the mail, and the yeast packet is like 4x larger than what I was using before.

My first thought would be to call NB Customer Support (phone number is with the kit instructions) to see how they would approach brewing the one gallon kits with a digital scale.

It just costs a retailer less to stock one size packet of yeast rather than two sizes. For small brews you just get bonus yeast to use for another brew.

Ok, I understand that with respect to the size of yeast packets. I’m reading “how to brew” and it still seems like around 2.5 grams of yeast would be appropriate for a 1 gallon brew. I added 7g approximately, and half of the packet would have been 5.75g. I guess we’ll find out in a month how it goes…

I know this is an old thread, but, I wonder if anyone ever got an answer about how much yeast we should actually be using with the 1 gallon extracts…

Take this as the opinion of someone who did a bunch of reading, but never did any real experiments…

Overpitching is a thing that can happen, but as homebrewers, we shouldn’t worry about it anywhere near as much as underpitching.

First off, if you look at what commercial breweries do, they pitch at much higher rates than typical homebrewers do. So the amount we would need to pitch to exceed the typical range of pitching rates would be silly large.

Second, the results of overpitching are generally pretty mild. You might get a cleaner fermentation, as there’s less of a growth phase (that’s where a lot of esters and other yeast derived flavors come from). If you harvest from the yeast cake of an overpitched batch, you might not have the healthiest yeast for the next batch. Now if you’re going for a stressed yeast flavor, like a funky Belgian or something, you might be more worried about this.

TL;DR, half a packet is common practice, and nothing I personally would worry about.

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Cool. Makes sense. It’s hard to know with tasting my beer whether or not it’s the right flavor, etc. I don’t have anything to compare it too.

There are a couple of good books out to help get you started on this. Being able to evaluate my own beer makes a major difference in my brewing hobby.

As for pitching rates for one gallon batches, I’ll offer the following:

  • if brewing a kit,do the the simplest thing possible: follow the kit instructions unless there are obvious typographic errors. If you plan to brew your own recipes, keep the 1/2 packet. If you’re not brewing your own recipes, throw it away.

  • When pitching for your own recipes, the simplest thing possible is to pitch (approximately) 1/2 packet. No need for a digital scale.

@uberculture covered the topic of off-flavors by over-pitching well.

That being said

  • If you check out HomeBrewTalk, you’ll find a lot of people who pitch 1/5, 1/4, or 1/3 of a 11 gram packet for their one gallon batches.

  • There was a presentation at the 2016 HomeBrew Con (available to paid AHA members) that talks a lot about brewing smaller (< 5 gallon) batches. Lots of good advice if you’re going to brew one gallon batches for a while.

AHA membership, along with HomeBrew Con presentations and 15+ years of Zymurgy online is easily worth $40 / year for a couple of years.

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