Potato Beer

When I was a graduate student at UC-Davis I attended a Master
Brewers meeting at the local Sudwerk Privatbrauerei Hübsch brewery
where I worked part-time as a brewer. The speaker at this particular
meeting was a retired brewmaster from the Lucky Lager Brewing Company
in San Francisco, which closed in 1978. The retired Lucky brewmaster
talked about what he did during WWII to keep beer flowing from the
brewery when corn and rice adjuncts were rationed and unavailable to
brewers. He told of using potatoes as a replacement for rationed raw
materials commonly used by brewers as adjunct grains. If my memory
serves me right (this talk was given in 1993 or 1994) he used dried
potato spuds. Before diving into this question I bought some dried
potato spuds and verified that they are easy to handle and could have
been received, stored and conveyed like other dry raw materials used by
brewers. They also are extremely easy to hydrate.

So there is a precedent for potato beer. When you add potatoes to beer,
be they boiled and mashed or dehydrated spuds, you must recognize that
you are adding starch. This starch must be converted by amylase enzymes
into fermentable sugars, just like any starchy brewing ingredient. The
gelatinization temperature of potatoes is around 140 °F (60 °C) The
other thing about potatoes is that they have a distinctive sulfur aroma
and I would remove these compounds before fermentation. That’s another
plus of using dehydrated potato spuds, since a lot of the sulfur
aromatics in wet potatoes are driven off with moisture during the
dehydration process.

The nice thing about potato starch is that it is not so different from
barley starch. It normally contains a bit more amylose than barley
starch (different varieties of potatoes and barley have different
amylose and amylopectin profiles), but usually is about 50% amylose and
50% amylopectin. It also has a gelatinization temperature similar to
barley starch (of course the dehydrated spuds are already gelatinized).
What this means is that potato starch will behave quite normally in the
mash and even if you decided to use “raw” potatoes instead of
dehydrated spuds you would not have to boil the potatoes before
mashing. If you shredded your tubers using a cheese grater as if
preparing hash browns the potatoes will hydrolyze like the endosperm of
malt when added to the mash.

I think the use of potatoes makes a lot of sense and you do have
history on your side. But you also know now that their use by US
brewers seems to have stopped after the rationing of food crops during
WWII . . . so one has to wonder why it was discontinued. ‘Taters are
certainly cheap, so my guess is that off aromas may be an issue in some
cases.

If I were you I would brew some more batches, but would use step mashing
to convert the potato starch into fermentable sugars.

While we’re on the subject, I have to admit that I have considered
using potatoes for an Irish dry stout for a really geeky reason;
Ashton, Idaho is known as the potato seed capital of the world, my name
is Ashton and there was something in Ireland’s history related to
potatoes. Like I said, pretty geeky!

Response by Ashton Lewis.