Reduced Mash Times

There are some brewing topics I address because I have been asked, and some
subjects I opine about whether asked to or not. And there are some
things I tend to avoid. Technique is heavily influenced by opinion and
personal preference. Unless there is something really “wrong” with a
particular technique, I tend to keep my mouth shut. Perhaps I have
failed our readers by biting my tongue and I will attempt to redeem
myself today!

There are some techniques that many all-grain
homebrewers practice that are at best a waste of time, and at worst may
have a detrimental affect on beer flavor. One is mashing time. It seems
that almost all recipes call for an infusion mash time ranging from
60-90 minutes and recipes using multi-temperature mashes are usually a
bit longer.

The truth is that malts these days are considerably different than
malts from the past. Malt modification is usually very good, even with
most European malt, and the enzymatic strength of certain barley malts
(mainly 2-row varieties from North America) has increased over the past
30 years. This means that the goals of mashing can often times be
accomplished in much shorter time periods when modern barley malts are
used in brewing.

When I say “modern” I am referring to malts made from new barley
varieties that have been bred to address the requirements of the modern
brewer. I have pointed out numerous times that Klages barley is no
longer grown, yet brewers still equate U.S. 2-row barley with Klages. I
remember in the early 1990’s going to annual barley crop reports given
by Great Western Malting Company and hearing then how few acres were
seeded with Klages. Things change with brewing raw materials and unless
brewers remain up-to-date with current trends, brewing literature
quickly becomes dated. Harrington, BA1202 and AC Metcalf are the
varieties that really replaced Klages in the West.

Most brewers want to accomplish a few primary goals during mashing. The
first is to convert starch into fermentable and unfermentable sugars
that end up giving beer the potential for alcohol and some residual
carbohydrate that lends body and character to beer. The second goal is
to yield as much of this extract as possible. Undermodified malt
contains intact cell wall constituents (beta glucans and proteins) that
make this secondary goal more difficult and is the reason that more
intensive mashing methods are used when brewing with undermodified
malt. The third goal, which is really an extension of extract yield, is
to make extract recovery easy.

When brewing with North American 2-row and 6-row barley malts the
brewer can usually assume two truths. The first is that there are
plenty of enzymes present in the malt to easily convert the starch in
the malt plus additional starch from adjuncts (e.g., rice and corn).
The second truth is that the malt is probably well modified.
Assumptions are often times dangerous, but these two can usually be
taken to the bank. The large brewers who buy and specify the majority
of North American barley malt require high enzyme content and uniform
modification and that’s what their suppliers produce.

Assuming you are brewing with North American barley malt you have two
basic options. You can choose to mash for 60–90 minutes because that’s
what 95% or more of most brewing recipes dictate. Or you can mash for a
shorter time period, for example, between 20–45 minutes, because that
is all that is required for many beer styles. The long mash is safe and
you are assured to have no conversion problems. The shorter mash times
may cause problems if you get too aggressive on the low end, do not
check for conversion using the iodine test and mash off at the end of
the mash. But if you check for conversion, reduce your mash time
gradually over time and do not mash off, you can successfully shorten
your mash times with no problems.

I’ll pause here and put some practical thoughts into this based on what
you did with your recent brew. You mashed for 20 minutes and then
recirculated the wort to clarify it before collection. I’ll assume this
recirculation took 20 minutes. If you did not raise the mash
temperature above about 158 ?F (70 ?C) you were actually mashing for 40
minutes. It just happens that you were mashing and recirculating during
the same 20 minutes interval. The second comment you made about your
experiment is that your yield did not change. Yield is one of the keys
to mashing I list above and since the yield did not change from your 90
minute mashes you can logically conclude that 90 minutes is not
required to achieve good yield (although the result from one trial is
not enough data to draw any real conclusions).

Many pub brewers who do not mash off use a mash duration similar to
what you used and in some cases the “short breather” is as short as ten
minutes. Again, it is important to understand from a biochemical view
that the enzymes active in the mash do not recognize stages of mashing
like “mash rest,” “recirculate” and “sparge.” Enzymatic reaction rates
are primarily affected by temperature, pH and substrate/enzyme
concentration. As long as the conditions for enzymatic reactions allow
enzyme activity the mash continues.

Even in mashes where the temperature is raised to mash off (usually
around 168 °F/76 °C) after a relatively short conversion hold around
158 °F (70 °C) is complete, the extract yield is good and fermentable
wort flows easily from the mash tun. In other words, the primary goals
of mashing are accomplished.

I stated earlier that, at best, long mashing is a waste of time and, at
worst, long mashing can cause problems. I want to elaborate on this and
briefly give two examples of problems stemming from long mashes. The
first is that if you are using enzyme-rich malt you may end up
producing wort that is more fermentable than you really want, resulting
in a beer that has a thin character. One way to brew light beer is to
use an extended mash between 145–150 °F (63–65 °C). The best selling
beer in the United States — Bud Light — uses this method and their
mashes last over three hours. If you want really fermentable wort, this
method accomplishes your goals, but if you don’t want this type of
wort, then the method is not a good fit for you and your beer. This is
an extreme example, but illustrates how mashing time does far more than
simply make for a negative iodine reaction.

Mash time also influences the amount of flavor extracted from the malt
during mashing. A few years ago we reduced the mash time used for our
helles-style lager and immediately detected the absence of a subtle
grainy off-flavor that we wanted to eliminate from this brew. At first
we suspected that the change in mash schedule and beer flavor may have
been related through a fluke, but repetition validated the
relationship. Five months later, we bagged a gold medal at the GABF in
the European-style Pilsener category.

I’ll quickly finish with two more opinions about technique without much
elaboration. Opinion #1: Many brewers recirculate their wort after
mashing for an arbitrary time period that at times unnecessarily adds
time to the brew day. You want to get the weak wort (weak because of
water usually used to cover the false bottom) from the bottom of the
mash tun back to the top of the mash before collecting wort and to get
the wort reasonably clear. If you can do this in five minutes instead
of 20, more time is not required to accomplish this brewing objective.

Opinion #2: Many brewers collect their wort over a period of about 90
minutes because pundit-brewers state as fact that short wort collection
times reduce yield. In contrasting fact, most commercial brewers try to
collect their wort as quickly as possible because the lauter tun is the
most expensive vessel in the brewhouse and is also the bottleneck to
production speed. These brewers are keenly aware of extract yield and
short wort collection time is usually limited by lauter tun design and
not the ability to achieve good yields. When I was a brewing student at
UC Davis, I brewed a lot of beer on a 5-gallon pilot brewhouse. Our
wort collection times usually lasted between 30 and 45 minutes and
yield was always quite good.

This answer was rather long, but it’s possible the five to ten minutes
it took to read may shave two hours from your all-grain brew day.
Hopefully this was a good investment of time!

Response by Ashton Lewis.