The Williams Brothers Brewing Co. in Alloa said the Nollaig Festive Ale, which includes the tips of needles from spruce trees, is based on a Viking recipe and all 800 bottles made this year have sold out, The Scotsman reported Wednesday.
The company said production of the $20-per-bottle beer will be boosted to 10,000 bottles next year due to the popularity of the beverage.
Brewery Chairman Scott Williams said the ale uses the tips of spruce tree needles picked before the start of brewing in April.
"It's used as a spice," Williams said. "Imagine you're making a stew and the malted barley is the meat and gravy, the spicing usually from the hops. Here it's the hops and the spruce. It goes into the boil and all the resins and flavors are extracted from the tips which are then fermented.
"So you have a malty, sweet characteristic from the barley, while the spruce is perfumey, but also quite resiny, so that adds feel to it, and the hops are bitter. The idea is that you get all three ingredients working in balance."