Determination of propionates and propionic acid in bakery products using gas chromatography

A simple analytical method for the determination of propionic acid and propionates in bakery products using a simple sample preparation procedure is described. The method involves the conversion of propionates to the non-ionized molecular form by adding glacial acetic acid, which is at the same time efficiently extracted into dichloromethane. After vortexing for 1 min, the extract was directly injected into a capillary gas chromatographic column with flame ionization detector. The method was applied for the determination of propionates in 112 commercial bakery samples. The levels of propionic acid plus propionates in bread, cake/ rolls, burger/hot dog buns and pita breads ranged from 197-1273, 98-1846, 546-1932 and 479-1680 μg mL^-¹, respectively. No propionate was detected in any of the 36 biscuit samples analyzed.