Partial Mash Brewing Guide

The image above of the cooling down of a partial mash boil in the kitchen sink full of ice likely brings back fond (or frustrating) memories for brewers of when they first got started.

Why Partial Mash?

Most brewers are introduced to the hobby by wandering into a local home brew shop and getting a starter equipment kit (normally under $100 USD depending on what's included), and an extract recipe kit to use with that equipment.  The most basic of the kits are cans of pre-hopped liquid malt extract with an extra bit of fermentables in the form of dry malt extract.  These are very easy to use (basically sanitize everything and mix with warm water then pitch the yeast) and generally produce a drinkable product for very little effort.

On the other end of the spectrum are the all grain brewers that perform a mash on malted barley and convert their own sugars to a fermentable state. Boil the full volume of wort, design recipes in software to style guidelines, and all sort of other things that require an incredible amount of effort compared to the extract kits.

Somewhere in the middle of these two is the partial mash brew.  Originally I viewed it as a step between the simple extract kits and the full commitment to all grain that was simply another step in the process.  I personally only did around six partial mash brews (and only two extract brews before that) before jumping to all grain.

Recently however several friends have shown interest in the hobby but don't quite want the full commitment of purchasing the equipment and keeping up with the details for an all-grain brew day (around 7-8 hours for my setup).  So they would try a simple extract kit from the local shop with the plastic bucket economy equipment kit.  Sure enough they loved having their own beer to drink at home but wanted more control over the process/beer that wasn't offered in extract kit form factor.

This is where the partial mash shines, great control over the process (relative to extract), wider selection of styles, low equipment costs, and a much shorter time commitment for each batch.  With the addition of a small amount of specialty grain to the extracts that contain many of the fermentable sugars you can achieve the body and depth that's often missing from extract only brews.I am actually a very big fan of the partial mash process now for the casual brewer. Not everyone needs a miniature commercial brewery in their basement, and truth be told you can make incredibly good beer with the process.  The guide below lays out the general process of completing a partial mash kit I purchased for this post.

More after the Jump

First Year Hops

Well it's been nearly a month since I planted hop rhizomes and they are looking pretty good. I've had almost two feet of growth on the Nugget and a foot on the Cascade. I was concerned about the Cascade when I received them in the mail. The rhizome had been broken in the mail and looked pretty rough. I went ahead and planted them and I'm glad I did. They are a little behind the Nugget but they still look nice and healthy. Can't wait to see the yield in the fall. I know they won't produce mush being first year plants, but things are looking good. I'll keep posting updates on their progress throughout the year.

Cascade - 4 weeks

Nugget - 4 weeks

Brew Day Data

We usually try to take as much data as possible on brew days.  Some items are for repeatability when we want to recreate a real winner.  Even if you don't really brew the same beer that often  (we rarely do) it can still help future brews of similar styles or even your brewing process as a whole.  Other data just help keep the day on track.  I thought it would be of some value to go through some of the items we try to record and why.

Ingredient Measurements - This one is pretty obvious, you need to know what you put into the beer first and foremost.  You can go a little further than pounds of grain and ounces of hops though.  What brand of each grain and even the age of the grain (if you buy in bulk and store grains for a period of time) can help isolate what went wrong later if there is an issue.  Same goes for hops, alpha acid percentage and age are useful items to keep up with.

Water Volumes - We have calibrated all of our kettles with a sight glass and try to use accurate water measurements for the mash.  This is important because you should be doing a temperature calculation that takes into account the amount/temperature of the water and the pounds/temperature of the grain to hit your mash temperature after you combine the two.   You also want to target a good mash thickness for optimal conversion, 1.25 qts/pound (2.6 L/kg) is the standard number most people stay around.

Gravity Readings - Yes readings in the plural.  You can get away with just a starting gravity at the end of the brew day but we've usually taken gravity readings at several spots during the day.  If you have an efficiency/conversion problem early on in the day you have a shot to fix it before the boil, after the boil, or just scrap the day and move on.  We use a refractometer so it's quick and easy to take a reading, there is no way we would do this many with a hydrometer.  As a general rule we look at: 

1. First Running out of the mash
2. Each Sparge (if you get too low you are extracting tannins)
3. The Pre-Boil gravity of the combined runnings
4. Post Boil Gravity (this is the starting gravity)

Mash Ph - We check the Ph of the mash somewhat infrequently, grab some test strips and see what your local water and grain come out to and adjust if needed.  Once you learn what you usually get you should be fine.  5.2 to 5.4 is the normal desired range.

Mash/Boil/Hop Times - Just recording the mash and boil times for the record, it can be quite hard to remember if you did a 60 or 90 minute boil three weeks later.  The hop schedule is crucial as the length of time in the boil affects bitterness in very different ways.

Volume of Wort Collected -  This will help you identify losses in your brew house due to dead space in equipment, evaporation due to boiling, and any other losses.  Use this to dial in your equipment profile in your brewing software or in your water calculations.  You don't want to end up way short or way over on how much beer you make.

Yeast - What strain was it.  What lot # if it was purchased or what generation was it if you're keeping your own supply in the freezer.  Did you build a starter and if so how big was it and how long did you let it go.  Yeast really is one of the mysteries of brewing that can have the greatest effect on flavor and quality of your finished beer.  Know everything you can about it.  We once had a bad batch that we couldn't figure out, turned out the package we used had been recalled by the manufacturer for poor performance.  We were only able to confirm that this was the issue by checking the recorded lot#.

Fermentation Temperature - Going back to yeast again, a second batch that had an off flavor was likely caused by a higher than desirable temperature range during fermentation.  Know where you're going to ferment and what temperature you expect it to be.  Add a few degrees to that (yeast produces a little heat when active) and select a yeast that performs well in that range.  Even better build a controlled fermentation space.

Final Gravity - If you want to know how much alcohol is in your beer (or if it's finished) you need a starting and finial gravity reading.

Bottles Bottled - If you're bottling it lets you get a good idea of how much fermenter volume you're losing to the yeast cake and any trub left in the wort before fermentation.

Priming Sugar - Type and amount.  See our post on natural carbonation here. 

Does anyone else record other information about their brewday?  I'm always interested in improving the process.  If you have anything we should lookout for or if there's an error in anything above let us know in the comments.  I'm also trying to decide on the next post does anyone have an opinion on which post they would like to see first, making a yeast starter or a discussion on fermenters (buckets/better bottles/glass carboys)?