2,3-Pentanedione is a common constituent of synthetic flavorings and is used to impart a butter, strawberry, caramel, fruit, rum, or cheese flavor in beverages, ice cream, candy, baked goods, gelatins, and puddings. 2,3-Pentanedione also occurs naturally as a fermentation product in beer, wine, and yogurt and is releasedduring roasting of coffee beans[1].

References:
[1]. Morgan DL, et al. Bronchial and bronchiolar fibrosis in rats exposed to 2,3-pentanedione vapors: implications for bronchiolitis obliterans in humans. Toxicol Pathol. 2012;40(3):448-465.