Study of enzymatic determination of food additives. Part II. Enzymatic determination of propylene glycol in commercial foods.

A simple and specific method is described, for the determination of propylene glycol (PG) in commercial foods. The method is based on the oxidation of PG by propylene glycol dehydrogenase (PGDH) from Microcyclus eburneus, which is accompanied by the reduction of NAD+ to NADH. PG separated from foods by extraction with deionized water and ultra filtration was readily determined by measuring the absorbance at 340nm. The use of an enzymatic reaction resulted in almost stoichiometric oxidation of PG, and the method was relatively free from interference. Recoveries of 2 and 10mg/g of PG from several foods ranged from 85 to 95% for 2mg/g and 95 to 99% for 10mg/g with a detection limit of 2μg.