The blue tint comes from spirulina, an algae that is grown in basins by a company called Etika Spirulina in northern France. The component of the spirulina that gives the blue colour, called phycocyanin, is then added to the beer during the brewing process, Reuters reports.
Tasting a freshly produced bottle of the beer, brewery employee Mathilde Vanmansart described it as hoppy, light, and with fruity notes, while the only evidence of the added algae was the distinctive colour.
Xavier Delannoy, whose farm provides the spirulina, said after several test batches, the brewery had found a blend that appealed to customers.
He said 1,500 bottles of the blue beer were sold between October and December last year, and the brewery is now preparing to ramp up production to meet demand.