Splitting Batches for Variety, Experiments, and Volume

For homebrewers, there are never enough brewdays. Our jobs, families, friends, and other hobbies fill our schedules, leaving us less time than we would prefer for making sweet wort.

One way to take full advantage of these fleeting brewdays is by splitting batches, creating more than one finished beer from a day’s work.

Why Split Batches?

Other than variety, splitting batches allows the brewer to experiment with ingredients, yeasts, techniques, and equipment. The possibilities are endless, but I have given a few examples throughout this post to help get the wheels turning.

Another reason to split batches is equipment limitations. Though I split several five-gallon batches beforehand, I honed these techniques after increasing my brew length to ten gallons. Because I only have 5 and 6.5-gallon fermentors, my equipment forces me to split batches after the boil. As so many homebrewers do, I used this limitation as a base for creativity and learning. Split-batch experiments are now commonplace for me, and I rarely make ten gallons of the same beer from the same wort.

I won’t concentrate on equipment limitations in this post, but I think the following methods and recommendations are applicable on any scale. If you understand your brewery, you can navigate any of these techniques within it.

Where to Split

If I said there was a point in the process in which a batch could not be split, there would be a homebrewer that could tinker his/her way to proving me wrong.

Practically, we will focus on splitting wort or beer before the kettle, fermentor, keg, and bottle. Generally, more preparation is required when splitting earlier in the brewing process. As such, we will work our way backwards, starting at packaging. 

Splitting at bottling allows the brewer to execute most of his/her process as normal. It is a great tool for all experience levels.

Use multiple bottling buckets or dose individual bottles with different ingredients.

Experiment ideas:

• Different priming sugars: dextrose, unrefined sugars, honey, DME, liqueurs, maple syrup, candi syrup
•  Different priming yeasts
• Different levels of carbonation
• Bottle one portion 'clean' and one portion with brettanomyces or bacteria.
• Wild yeast ‘spikes’

The last idea is my personal favorite. Though I have done structured experiments, normally I just dose a few bottles with brettanomyces or a mixed culture on bottling day. This works best with a very dry beer (like a saison or Tripel) but is (at least) an interesting experiment across all beer styles. If the beer's final gravity is above 1.006 or so, use heavy bottles.

Splitting in kegs offers many of the same benefits and experimentation options but has the added benefits of reducing oxygen exposure, easy transfer, and easy sampling. It is also a fine method for quarantining brettanomyces and bacteria for those who may otherwise fear cross-contamination. 

To split a five-gallon batch, rack the entire volume into one keg first, which simplifies racking and allows for more accurate measurement. I use my grain scale to measure the split by weight during transfer. I plan to give more details on this process in an upcoming post on blending, as well as during my presentation at this year's NHC.

Experiment Ideas:

• Explore dry hops or cold-side additions
• Create a small, 'special' portion of beer on the fly (one gallon of "Christmas Stout" from a keg of oatmeal stout)
• Blending
• With beer (sour saison, historical porter, gueuze)
• With other fermented liquids (wine, mead, cider, spirits)
• With water

Transferring a small portion of finished beer onto fruit or spices can yield a unique offering for a festival or party. I also love using this method for adding fruit or oak to a portion of a sour batch. 

Splitting before fermentation is standard procedure for most homebrew batches greater than 5-6 gallons. However, the same split can be done at any brew length with a few minor considerations.

For instance, a 5 gallon batch can be split into two 5-gallon fermentors for primary fermentation. Because the amount of beer lost to yeast and trub will nearly double, increase the batch size by a gallon or so to compensate (if possible within your system). 

For beers requiring long conditioning times, and especially for sour beers with mixed cultures, transfer the beer to a smaller container to minimize head space during conditioning. Excessive head space significantly increases oxygen pickup over time. Small better bottles or one-gallon growlers  are inexpensive and work well! Small kegs are a fantastic option if you have them.

Experiment Ideas:

• Different yeasts
• Different fermentation specs: pitch rate, oxygen, temperature (vary one, keep others constant).
• Sugar or fermentable comparison: candi syrups, honey varieties, fruit
• Sour beer base!

If I don't have another experiment in mind, half of my 10-gallon batch is normally spiked with my mixed culture and allowed to conditioned for a year or more. As these 'other halves' come to maturity, each offers a 5-gallon batch of sour beer to blend, fruit, or bottle as-is without a dedicated brewday. Talk about a big return on a small investment!

Splitting before the boil requires some additional planning and (potentially) equipment to be successful, but I think its less daunting than a decoction or turbid mash.

When splitting pre-boiled wort, most homebrewers think parti-gyle: splitting the wort into portions (or 'gyles') of different strength. Most often, this is executed by separating the first and second runnings of a batch sparge mash. Parti-gyle can produce an infinite number of wort combinations, and executing a parti-gyle brew can be as simple or complicated as the brewer wishes. Since I have never used this method, I'll refer you to Ron Pattinson and Randy Mosher for more information and tips:

Ron Pattinson. “Parti-gyle: Debunking the Myths”. Zymurgy, November/December 2014.

Mosher, Randy. "Parti-Gyle Brewing". Brewing Techniques, March/April 1994. Online:
http://morebeer.com/brewingtechniques/library/backissues/issue2.2/mosher.html

Another option is to collect all of the pre-boil wort in the kettle, then transfer a portion before (or during) the boil. I use this method to remove hops from a portion of the batch for sour beer base or pressure-canned starter wort.

Experiment Ideas:

• Different kettle additions: hops, spices, finings, yeast nutrients, water salts
• Steep specialty grains to create different base beers from one mash: pale ale vs. stout, Flanders Red vs. Oud Bruin.

Practical Recommendations (for split boils)

Plan ahead. A successful split will take more time, ingredients, equipment, etc. than a single, straight-forward batch.

Map out the split in your brewing software of choice. For split-boils, I use BeerSmith to create a full size malt bill, then scale the batch and save as separate recipes. This allows me to calculate hop additions, bitterness, steeping grains, yeast pitches, etc. at the proper volume. Check out the recipes from a recent split batch, "Raw Grain Saison", on my BeerSmith Recipes page.

For parti-gyle calculations, several tables are given in the Mosher article listed above. Kai Troester provides a batch sparge calculator on his website (BrauKaiser.com). It is effective but requires some efficiency inputs for your system. I dialed in the sheet with guess-and-check using numbers from previous batches.

Organize your brewday. Because you planned ahead, you know how the brewday should progress, what equipment is needed, and where ingredients will be added.

Measure (and label) salts, hops, spices, finings, and yeast nutrient additions. I like using lidded, 4-oz plastic containers because they are cheap and won't spill if (when) I drop or knock them over.

Position all necessary brewing equipment before you start brewing. Make sure you can get liquor, wort, and cooling water everywhere it needs to be along the process. Also make sure that everything is in reach and you won’t be constantly tripping over hoses, propane tanks, pump stand, etc.

Offset your boil by 15 to 30 minutes (or more) if you will need to share critical equipment: chiller, pump, cooling water, etc. This offset can also be helpful for the brewer already juggling multiple transfers, measurements, and kettle additions, along with copious note-taking. Speaking of…

Practical Recommendations (in general)

Plan ahead. Prepare yeast, sanitize enough fermentors, have enough bottles or kegs. For experiments on bottling day, set up all your equipment and have your mise en place in order.

Prepare enough healthy yeast. You may need to make multiple starters, or propagate with multiple steps.

Take detailed notes. Whether the goal is experimenting with new ingredients or comparing a process change, the additional effort required for splitting a batch loses its value if the results cannot be repeated (or adjusted). Don’t rely on your memory to recount the specifics of a brew day, gravity measurements, fermentation profile, blend percentage, etc. after the beer is finished – it is already overloaded with juggling split batch tasks!

Label EVERYTHING: starters, hop additions, fermentors, kegs, and bottles.

Practice Makes Perfect. The more times you split batches, the more comfortable and confident you will become with your process. 

Hopefully you can use some of these ramblings to make multiple beers from a single brewday! Let me know what you brew up!

Get to splittin'!