Beer of spontaneous fermentation, the Oude Quetsche Tilquin à l'Ancienne is made from the fermentation of destoned fresh purple plums in young lambics, blended with 1, 2 and 3 year old lambics to reach a final concentration of fruits of 260 grams of yellow peaches per liter of lambic.

Unfiltered and unpasteurized, this beer is refermented in the bottle.