Biere de Mars Our bottle-conditioned Biere de Mars is typical of those brewed in the shoulder of the season (specifically March) to make something sessionable for the summertime. Containing a gorgeous orange hue, this beer derives its intense puckering character from the use of a sour mash. This occurs when the brewer lets the wort sit on the grain and the natural bacteria and yeast sours it. After a subtle sweet fruitiness hits your palate upfront, a long tart finish quickly takes over.