Ask Mr. Wizard

Brewing Light Lagers

TroubleShooting

Mike Brown asks,
Q

In preparation for spring I want to come up with a good plan to brew a light lager beer. When I say light, I mean lower in calories and alcohol than the average 5% beer. Do you have any suggestions that will help me?

A

Brewing light lagers that have very subtle flavors atop a stark
white canvas is difficult. Little flaws in the recipe balance and
off-flavors easily masked by bigger beers stick out like a fleck of
pepper in a bowl of milk. There are a few basic tips that will help get
you started and the first concerns water. The best thing to do for this
style is buy reverse osmosis water from a local grocery store and add
water salts to produce water with about 50 mg/L of calcium. I prefer to
use calcium chloride for this type of beer because chloride has a softer
effect on flavor than sulfate. If you use calcium chloride and add 0.02
ounces per gallon (0.14 g/L) of mineral free water you will have the 50
mg/L of calcium I suggest.

The next ingredient you need to select is malt. If you are not an
all-grain brewer, consider delaying this brew until you begin brewing
using mashing as part of your routine. The type of malt you select is
really up to you. Clearly pale-colored malt is required, but you have a
pretty wide selection of pale lager malts to choose amongst. If you plan
on using adjuncts you may want to use some 6-row malt in your grist
bill, but many of today’s 2-row malts produced from North American
barley have enough enzymes to handle up to 15–20% adjunct with little
problem. Light beer is not the style to start adding a bunch of special
malts, but if you do want just a little color and malt flavor a dash of
higher kilned pale malt, such as 10 °L Munich malt, or crystal malt can
be used. Just don’t get carried away with these ingredients because a
little bit goes a long way.

Next is the most critical process to consider; mashing. The underlying
principle to light beer brewing is the production of wort that is highly
fermentable and there are two ways to achieve this goal. The easiest on
paper is to add exogenous enzymes (enzymes from sources other than
malt) to the mash. The best way to produce very fermentable wort,
however, is by controlling the mash. Not only is this relatively easy,
but it works very well. The main difference, however, is that extended
mashes do not hydrolyze all of the malt starch into fermentable sugars
so there is residual carbohydrate in beers using extended mashing. For
this style of beer you want to have a wort gravity somewhere between 8–9
°Plato or 1.032–1.036.

The type of mash you need to use is a multi-temperature step mash. I
suggest beginning your mash at about 122 °F (50 °C). This first step is
used by some brewers to encourage proteolytic activity, but for this
style it is just a good starting point to get your water and malt
properly mixed together. A good ratio of water to malt for this style is
about 3.5 parts water to 1 part malt by weight (3.5 liters water per
kilogram malt or 0.42 gallons per pound). Hold the mash at your mash-in
temperature for about 15 minutes and begin heating toward a target of
145 °F (63 °C). It is absolutely vital to this type of beer not to
over-shoot the target temperature. A useful technique is to shut off the
heating when you get to about 140 °F (60 °C) and let the mash
temperature settle. Then slowly heat up to 145 °F (63 °C). Why is this
so critical? Well the whole purpose of this method is to hit a
temperature where both beta and alpha amylases are happy and to hold
this temperature for at least two hours . . . that’s right, two hours
minimum! If you want to go longer you can, but at some point the rate of
change in an enzymatic reaction approaches zero as the concentration of
substrate approaches zero.

This is all very easy for me to explain, but the execution is not easy
because the mash cools off fairly quickly. In a commercial brewery
things are controlled automatically and as the mash cools the heating
jackets and mash agitator kick on and off to keep the mash temperature
within a defined control range. You are going to have to do the same
thing at home by carefully monitoring the mash. I think two to two and a
half hours is a reasonable time to fuss over the mash.

After the long hold at 145 °F (63 °C) is over you need to heat the mash
up to about 158 °F (70 °C) so that alpha amylase can reduce the size of
any large starch molecules that may have survived. After a brief 10–15
minute hold, mash off at 168 °F (76 °C) and transfer to the lauter tun.

Things are pretty standard from here on out; boil for 60–90 minutes and
use a modest hopping rate during the boil to target around 10–20 IBUs,
depending on your personal preferences. Cool the wort down to around
50–55 °F (10–13 °C), aerate well and pitch a clean-fermenting lager
yeast strain. If you pitch at a proper level (about 10–15 million cells
per milliliter of wort) primary fermentation should be complete in seven
to ten days. Carefully rack to your secondary and store as close to 32
°F (0 °C) as possible for about 3-4 weeks to allow the beer to naturally
clear.

Response by Ashton Lewis.