Some guys will do anything on a dare. Clark Nelson, former head brewer at Coyote Springs brewpub in Phoenix, is reported to have made beer out of Cheerios while cruising aboard a Navy submarine.
I am ready to face my challenge. The staff at BYO let it slip that they doubted I could successfully complete a grain mash in a microwave oven.
Ye of little faith! Read on, brew trooper, and you will learn the secrets of radar range mashing!
The real origin of the story is a bit mundane. One morning, as I was zapping my daily bowl of oatmeal in the microwave, I was overcome by the hare-brained idea. Oatmeal lovers stopped cooking their porridge on the stove top years ago in favor of the convenience of the microwave. It is quicker and cleaner and requires no pot scrubbing.
I thought: “Why wouldn’t those advantages apply to the brewer’s mash?” Of course they would. And unbeknownst to the doubtful skeptics on the BYO staff, I had a secret weapon: the temperature probe!
I have an old Kenmore microwave. It was built about 10 years ago, during the brief period when microwave ovens came with strange — and largely ignored — accessories, such as temperature probes. The temperature probe looks like an ice pick wired to a quarter-inch headphone plug.
A mated quarter-inch jack is mounted inside the oven. The idea was a product of the days when microwave designers actually believed their consumers would cook in the microwave. You know, Sunday dinner roast beef with potatoes, carrots, all the trimmings, in half the time.
The ice pick was to be inserted into the meat, then plugged into the jack. The oven was programmed to zap the meat until it reached a predetermined internal temperature, according to the tastes of the user.
The thing really works. The problem, as we all know, is that cooking roast beef and Sunday ham in your microwave is not the best way to coax the flavor, color, and tenderness out of the meat. Meat cooked in the microwave comes out tough, gray, and rubbery. It’s not exactly appetizing.
Legions of microwave owners filed the ice pick away with the microwave recipe book, never again to see the light of day as the oven was relegated to its truly useful purposes: heating cold coffee, popcorn, burritos, TV dinners, and leftovers.
I was one among legions. In fact long before my brewing days, I had thrown my probe away, knowing I would never use it.
My mother, on the other hand, saves everything. She still had hers. When the micro-mash idea hit me, I quickly appropriated mom’s — with her permission, of course.
My microwave’s temperature program range is 115° to 200° F. Is that perfect for mashing or what? Another reason I could pull this off is that my oven is one of the big ones. Tall and deep with a removable wire shelf. I knew I could fit a pretty big mash tun in there.
I decided on a recipe, Belgian Strong Ale. Not for any particular reason, except that I had never made one before. Plus, I found it humorously ironic to imagine a Trappist brewer toiling away in a Belgian Monastery tapping temperature commands on a Kenmore microwave. The recipe was based on Dave Miller’s Trappist Ale from Brewing the World’s Great Beers.
I planned to make this beer all-grain but when weighing out the malt at the homebrew store, it became evident that even my oversized microwave was not big enough to accommodate 10 pounds of malt and 10 quarts of water. I switched gears and pursued a mash/extract version instead.
To take full advantage of my techno-power, I chose a temperature-program mash. I would use a protein-developing step mash, bringing the mash to around 120° F and resting there for 30 minutes before proceeding to a 60-minute conversion, holding at 155° F.
According to author Charlie Papazian, the “protein-developing step mash” will improve head retention, reduce chill haze, and assure development of adequate yeast nutrients. Step mashing is also recommended when adjuncts (sources of starch other than malt) are present.
Since this was to be a strong ale, I planned to use the mash process to convert some extra starch to sugar. I knew the Belgian ale yeast would be able to handle high-gravity wort. Hence, the addition of corn starch to the grist.
I added the raw barley only because it was sitting in my brew closet collecting dust and I could not bear the thought of throwing it away.
The Microwave Method
My wife uses an enormous porcelain mixing bowl for chocolate chip cookies, big salads, and the like. It fit in my microwave just right and was spacious enough for the mash.
First I zapped five quarts of filtered water, setting the temperature program at 130° F. The oven ran for 25 minutes before beeping to announce the temperature had been reached.
I sifted in the corn starch before mashing in the malt, adding about a pint of cold water until the temperature stabilized at 120° F. I reset the microwave program for 120° F and returned it to the oven for 30 minutes. During this time the oven activated very little. An unexpected benefit of the microwave method was that the thick porcelain bowl retained the heat of the mash. The oven had little work to do during the protein rest.
I stirred and checked the temperature once during the rest. My scheme was unfolding perfectly.
During the last minutes of the protein rest, I boiled a quart of water on the stove top. When the first rest was over, I added the quart of boiling water to the mash, stirred, and returned it to the oven, setting the temperature probe to 150° F. It ran at full power for 12 minutes to reach 150° F.
For the next 60 minutes I listened to the oven cycle on and off to gauge the power level it used to hold the temperature. It was actively nuking only around 10 percent of the time. Again, the heavy mixing bowl did a great job at holding temperature.
I stirred and checked the temperature three times during the conversion rest. The iodine test was just slightly stubborn after the first hour. I let it sit another 30 minutes and the iodine test was fine.
At the end of the conversion, I boiled two gallons of sparge water on the stove and increased the microwave setting to 170° F. It took the oven 15 minutes to reach the mash-out temperature, and I began the sparge/lauter.
My oven is rated at 600 watts power. You can expect shorter heating times with a more powerful oven.
If you want to try this at home and your oven does not have a temperature probe, zap the water at full power until you reach your strike temperature. During rests you will not need more than 10 percent power to hold the temperature, especially if you use a porcelain or earthenware bowl.
Stir occasionally during rests to distribute heat evenly.
Another potential use for the microwave in brewing is less messy, no-pot decoction.
And if you use a picnic cooler as a mash tun, you can remove and microwave a portion of the mash, returning it to the cooler to increase the overall mash temperature without thinning it by adding hot water. I did that once, after striking in a picnic cooler that I had neglected to pre-heat. The temperature dropped far below conversion range, and I used the microwave “decoction” method to increase the temperature.
Now, who said microwaves were just for frozen burritos?