Let’s see beyond the cheese and onion flavouring and celebrate the good old, reliable, comforting potato. Surprising, you may think, for a blog on a brewery’s website, but this nutritious, staple food source for many; and distilled to become vodka by many others, is about to be popularised even further as craft breweries have marked the potato’s next second coming – as the source of beer sugar for fermentation.
The potato has a long history. First cultivated by Inca Indians in Peru around 8,000 BC to 5,000 B.C., brought to Europe by the Spanish Conquistadors in the mid-16thcentury and by Sir Walter Raleigh to Ireland in 1589. In January 1835, naturalist Charles Darwin landed in the almost inhospitable terrain of the Chonos Archipelago (part of present-day Chile), where a particular plant caught his attention. This specimen later proved to be Solanum tuberosum, or the domestic potato. Testament to his skill as a collector, the actual, now 184-year-old plant he collected can still be seen on display from 12thFebruary 2019 at the RHS Wisley Library, marking 210 years since Darwin’s birth.
Here’s some Science...
In theory, almost any food that contains sugars, simple or complex (such as starch) can be fermented to become beer. Potatoes (and sweet potatoes, or sometimes yam [Ipomoea batatus] in particular) not only have a naturally high sugar content, but they also have enough natural amylase enzymes and diastatic power to convert their own starches to sugars without the need for additional processing.
Brewers can use either raw potatoes or unprocessed potato flakes in brewing. The percentage of protein in potato flakes is on par with the percentage found in malted barley, so ought not contribute protein haze to your beer.
Raw potatoes need a little prep for brewing. Simply peeled, cut into small cubes, and boiled for 15 minutes or so, drained and then mash the potatoes with a potato masher. ‘Mash’ here means crush or whip, not the brewing term.
Add the mashed potato to the foundation water in the mash tun. Once mashed in, brew the beer as normal, perhaps with some extra stirring.
The resulting neutral-flavoured mash is perfect for enabling all the floral notes of the hops to come through into the beer. Potato can dry out a beer though, but this simply results in a quaffable, dry, session ale.
The Beers
Loving a yam at Thanksgiving, Americans recognised the flavour potential of brewing sweet potato some time ago, resulting in today, quite a range of craft beers, dark and pale.
Japanese breweries are also experienced at using the sweet potato in brewing. Coedo brewery has produced the unique, award-winning imperial amber ale Beniaka since 2007. Brewed with roasted Kintoki Sweet Potatoes from Saitama, Japan, this 7% imperial amber ale is rich and smooth bodied with the aroma of caramel, sweet potato and hops.
Yet, no matter how much we love a potato, there are still kilos that go to waste every year. But in 2016, pioneering zero-waste Dutch company Instock, joined forces with an Amsterdam-based brewery to create a unique food-waste craft beer: Pieper Bier, made from rescued potatoes! The neutral taste of the potatoes causes the hop to stand out more, which translates into a floral bitter taste that is reminiscent of a Pale Ale. (Their more recent adventure has been to create a beer from ‘rescued’ bread.)
However, don’t use potatoes that have sprouted — potato sprouts and green potatoes contain solanine toxins and should be discarded. If your potatoes aren’t fit for cooking, they aren’t fit for brewing.
Overall, it seems the ubiquitous, multi-faceted, humble potato still has some tricks under its jacket. There is still plenty of potential in exploring the range brews that may be created with this mash for mashing.