Mash Yield/Fermentability Experiments

Wed, 1 Mar 1995

I have conducted some experiments on mash extract yield and fermentability as a followup to some work Dr. Fix reported on in Aug. 94 in HBD. I thank Dr. Fix for inspiration for this work and also for technical assistance in setting up the experiments and interpreting my results. I ran the experiments to determine the effects of the 40/60/70C mash program on yield and fermentability in my homebrewery. While I don't consider the results definitive in the realm of mashing grains, I do think they provide useful data on the effects of low temperature (40C/105F) mash rests and manipulating fermentability via 140F/158F mash rests.

Mash Yield Experiment

The following experimental mashes were conducted to determine the effects on extract efficiency in an infusion mash with the following options:

The following conditions were used for all experiments:

  1. Mash-in @ 155F - hold for 60 min. 'One-Step Infusion' extract efficiency = 55% = 1.024 s.g./lb. in 1 gal.
  2. Mash-in @ 155F - hold for 60 min - boost to 165-170 F - hold 15 min. grist doughed in at mash water rate of 1.25 qts./lb. grist - external heat boost to 165-170F 'Step Infusion_MO' extract efficiency = 64% = 1.028 s.g./lb. in 1 gal.
  3. Mash-in @ 105F (0.75 qts. water/lb. grist) - hold 30 min. - boiling water boost (0.5 qt./lb. grist) + external heat to 155F - hold 60 min. 'Step Infusion_BG' extract efficiency = 68% = 1.030 s.g./lb. in 1 gal.
  4. Mash-in @ 105F (0.75 qts. water/lb. grist) - hold 30 min. - boiling water boost (0.5 qt./lb. grist) + external heat to 155F - hold 60 min. external heat infusion to 165-170F - hold 15 min. 'Step Infusion_BG_MO' extract efficiency = 71% = 1.031 s.g./lb. in 1 gal.

Conclusions: Yield Experiment

Fermentability Experiment

Several experimental mashes were conducted to evaluate the effects on fermentability of 140F/40C rests of 0 min, 15 min., and 30 min. using a 40/60/70/75 mash program.

Details of this experiment are as follows:

Worts from the following three mashes were fermented:

Mash Rest Temp.105F/40C	140F/60C	158F/70C	167F/75C
Fermentability
High		30 min.	30 min.		30 min.		15 min.
Medium		30 min.	15 min.		45 min.		15 min
Low		30 min.	-		50 min.		15 min

Fermentation results are summarized below:

Fementability	Original Gravity	Final Gravity	Apparent Attenuation
High		1.052			1.017		67%
Medium		1.054			1.019		65%
Low		1.050			1.019		62%

Conclusions: Fermentability Experiment


Rob Reed
<rhreed@icdc.delcoelect.com>
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Spencer W. Thomas (spencer@umich.edu)