Yeast Mash experiments
Posted: Thu Nov 10, 2016 9:23 pm
In another thread I posited an idea of using yeast to scavenge oxygen in the mash in place of sulfites. The reason for wanting an alternative to nameta is for ale brewing since most of the yeasts do not tolerate sulfites well during fermentation. One big problem with this idea is that yeast die at typical mash temperatures and cannot continue to do their DO removal job all the way through to mashout. However if one doughed in at typical acid rest temperatures and held long enough for the yeast to scavenge the oxygen, you could then move as quickly as possible up to beta rest temperatures and at least limit HSA damage to the wort.
Today I had time to throw together a simple test to look at the basic process and I have posted all the results below. Based on the numbers generated by the second test, I feel confident that yeast can at least keep up with the diffusion of oxygen caused by mechanically mixing grain with water. It is doubtful a mash cap and gentle handling alone could be enough to stave off all oxidation while transitioning from 35c to 70c and mash out and therefore this method probably is not suitable for brewing lagers. However for ales the probable small amount of HSA from this procedure might be tolerable or even desirable. It definitely deserves more testing in a full batch of beer and I intend to add this to my ever lengthening 'to brew' list.
Run #1
Water RO 500ml Temp: 35c
Profile: Ca 30, Mg 4, Na 6.2, SO4 16, Cl 55
Yeast, dry: 0.22 gm (Lessafre bread type) Dextrose: 0.22 gm
Grain, 2 row 86 grams
Time - DO mg/l
0 - 7.5
6 - 7.03
20 - 1.69
41 - 0.31
1:04 - 0.32
1: 05 - add grain
1:07 - 0.70
1:12 - 0.55
1:18 - 2.82 (average, reading unstable)
1:25 - 2.49 (average, reading unstable)
1:57 - 0.34 (average, reading unstable)
At the 1:18 mark I started to get quite unstable DO readings from my meter. Re-calibrating it had no effect and then I also noticed quite a few bubbles in the electrolyte under the membrane. I had a new one and so decided to change the bonded cap membrane and electrolyte on the meter and start the whole test over again.
Run #2
Water RO 500ml Temp: 35c
Profile: Ca 30, Mg 4, Na 6.2, SO4 16, Cl 55
Yeast, dry: 0.22 gm (Lessafre bread type) Dextrose: 0.22 gm
Grain, 2 row 86 grams
Time - DO mg/l
0 - 6.34
10 - 4.75
20 - 1.95
40 - 0.25
58 - 0.31
1:00 - add grain
1:03 - 0.30
1:08 - 0.25
1:13 - 0.41
1:20 - 0.44
1:28 - 0.44
1:38 - 0.33
1:39 - Raise temperature to 65c
It took roughly 11 minutes to increase the temperature to 65c where I held for another hour. The sample jar was kept uncovered during the whole process and as typical in low oxygen mashes it was very difficult to smell. After conversion I sampled the wort and found it to be quite pleasing with usual lodo fresh malt flavors.
Note: These were mini type mashes done in mason jars and heated by water bath.
Today I had time to throw together a simple test to look at the basic process and I have posted all the results below. Based on the numbers generated by the second test, I feel confident that yeast can at least keep up with the diffusion of oxygen caused by mechanically mixing grain with water. It is doubtful a mash cap and gentle handling alone could be enough to stave off all oxidation while transitioning from 35c to 70c and mash out and therefore this method probably is not suitable for brewing lagers. However for ales the probable small amount of HSA from this procedure might be tolerable or even desirable. It definitely deserves more testing in a full batch of beer and I intend to add this to my ever lengthening 'to brew' list.
Run #1
Water RO 500ml Temp: 35c
Profile: Ca 30, Mg 4, Na 6.2, SO4 16, Cl 55
Yeast, dry: 0.22 gm (Lessafre bread type) Dextrose: 0.22 gm
Grain, 2 row 86 grams
Time - DO mg/l
0 - 7.5
6 - 7.03
20 - 1.69
41 - 0.31
1:04 - 0.32
1: 05 - add grain
1:07 - 0.70
1:12 - 0.55
1:18 - 2.82 (average, reading unstable)
1:25 - 2.49 (average, reading unstable)
1:57 - 0.34 (average, reading unstable)
At the 1:18 mark I started to get quite unstable DO readings from my meter. Re-calibrating it had no effect and then I also noticed quite a few bubbles in the electrolyte under the membrane. I had a new one and so decided to change the bonded cap membrane and electrolyte on the meter and start the whole test over again.
Run #2
Water RO 500ml Temp: 35c
Profile: Ca 30, Mg 4, Na 6.2, SO4 16, Cl 55
Yeast, dry: 0.22 gm (Lessafre bread type) Dextrose: 0.22 gm
Grain, 2 row 86 grams
Time - DO mg/l
0 - 6.34
10 - 4.75
20 - 1.95
40 - 0.25
58 - 0.31
1:00 - add grain
1:03 - 0.30
1:08 - 0.25
1:13 - 0.41
1:20 - 0.44
1:28 - 0.44
1:38 - 0.33
1:39 - Raise temperature to 65c
It took roughly 11 minutes to increase the temperature to 65c where I held for another hour. The sample jar was kept uncovered during the whole process and as typical in low oxygen mashes it was very difficult to smell. After conversion I sampled the wort and found it to be quite pleasing with usual lodo fresh malt flavors.
Note: These were mini type mashes done in mason jars and heated by water bath.