Big Rock throws stones… into its beer

Ancient brewing technique used in Erratic Stone-Fired Ale

The origins of beer can be traced back to the origins of society. So in the history of beer the use of metal vessels in brewing is new technology relatively speaking. Although almost 100 per cent of present-day brewers use metal brewing vessels there was a time when beer was brewed in wood. Of course you can’t heat a wooden vessel with fire so brewers would heat up stones and throw them in the brew.

This ancient brewing process is cumbersome and dangerous which is why almost nobody does it anymore. But the process of flash-heating liquid with red hot stones also creates hot spots in the beer burning the sugars within it creating caramel flavours and darkening the brew. These characteristics of beer were lost when metal brewing pots became readily available.

Thankfully Big Rock Brewery has brewed a beer using that ancient technique. Big Rock sourced granite from British Columbia (an initial test using local rock proved unsuccessful) custom built some equipment and set out to re-create brewing history.

Brewmaster Paul Gautreau formulated a recipe of five different malts and two different hops. On brew day the granite stones were placed in stainless steel baskets which were themselves heated over propane torches. The stones reached 700 C before one basket was lowered into the brewing kettle. This was sufficient to cause a vigorous boil and when the boil started to slow the basket was removed and replaced with another basket hot off the torches.

“One set of stones could boil the beer for 15 minutes and by trading the baskets off we boiled the beer for one hour and 15 minutes. It was really exciting to see the liquid erupt when we lowered the set of hot stones into the kettle” says Gautreau.

The resulting Erratic Stone-Fired Ale is deep ruby in colour. It has a moderate aroma with a nice maltiness and a touch of caramel. While the flavour is medium-bodied the beer has a low level of carbonation which gives it a soft presence in the mouth and allows its delicate sweetness to shine. There is also a light mineral taste similar to drinking hard water and a very subtle smokiness.

“I was trying to imagine what a beer like this would taste like 500 years ago” says Gautreau. “I think it worked out pretty well.”

To put into perspective how rare beers made in this fashion are of over 10000 commercial beers I have sampled Big Rock Erratic Stone-Fired Ale is only the fifth stone-fired beer I have had and the first from Canada. In keeping with that exclusivity theme Big Rock has made only 3300 bottles of Erratic (so run don’t walk to your favourite beer store).

It’s part of a return to craft beer for Big Rock after focusing more on volume for the past few years. According to new CEO Robert Sartor Big Rock will launch 15 new beers this year all of which will be limited editions.

“We will not brew a beer without a story” says Sartor. Using custom-made equipment to re-create a centuries-old brewing technique is a pretty cool story. Kudos Big Rock.