I've been brewing some test beers, 3 gallon batches, in my kitchen.
Because the mash schedules call for step mashes and the batches are small, I've been mashing them in the microwave. I did 2 batches like this, both with the same result.
Last night I mashed 5 pounds of grain with 5 litres of water for 2 hours. I have a digital temp probe. I held the mash at 66C (151F) or a little higher for most of the 2 hours. I transferred the mash into a double pail sparge setup and fly sparged it for 40 minutes.
The outcome was 3 gallons of wort with a SG of only 1.020 ! I've never suffered from low efficiencies prior to using the microwave for mashing.
There could be 2 causes as far as I can see.
#1) the microwave heats really unevenly. One has to heat and stir and heat and stir. My mash vessel was just an open plastic bowl. Heat was lost from the top and the sides. So even though my temp sensor said 66C (151F), parts of the mash were at higher or lower temperatures. Last night I specifically mashed for 2 hours to compensate for this.
#2) the microwave action might kill the enzymes.
As far as I can tell, the rest of my process was always like it was before, and I always got good efficiencies.
Next week I will try using steam to heat the mash vessel and the mash vessel will be a small cooler.
Because the mash schedules call for step mashes and the batches are small, I've been mashing them in the microwave. I did 2 batches like this, both with the same result.
Last night I mashed 5 pounds of grain with 5 litres of water for 2 hours. I have a digital temp probe. I held the mash at 66C (151F) or a little higher for most of the 2 hours. I transferred the mash into a double pail sparge setup and fly sparged it for 40 minutes.
The outcome was 3 gallons of wort with a SG of only 1.020 ! I've never suffered from low efficiencies prior to using the microwave for mashing.
There could be 2 causes as far as I can see.
#1) the microwave heats really unevenly. One has to heat and stir and heat and stir. My mash vessel was just an open plastic bowl. Heat was lost from the top and the sides. So even though my temp sensor said 66C (151F), parts of the mash were at higher or lower temperatures. Last night I specifically mashed for 2 hours to compensate for this.
#2) the microwave action might kill the enzymes.
As far as I can tell, the rest of my process was always like it was before, and I always got good efficiencies.
Next week I will try using steam to heat the mash vessel and the mash vessel will be a small cooler.