BENZOIC-ACID AS A NATURAL COMPOUND IN CULTURED DAIRY-PRODUCTS AND CHEESE

This review deals with the 'state of the art' of benzoic acid in cultured dairy products and cheese. During fermentation, benzoic acid is produced from hippuric acid a component of milk naturally present at concentrations of up to 50 mg/kg. In smear-ripened cheese, however, higher benzoic acid concentrations have often been measured on the surface or even inside such cheeses. A second metabolic pathway has been proposed: during ripening, an additional quantity of benzoic acid originates from phenylalanine degradation, with beta-phenyl-propionic (hydrocinnamic) acid and cinnamic acid as intermediate products. Acetophenone is a by-product of this breakdown, which essentially occurs in the rind and the smear. The presence of these intermediate products and their concentration gradient, the concentration of benzoic acid and its formation during cheese ripening, and the simultaneous production of ammonia resulting from deamination support the validity of this second metabolic pathway. A third way could be the auto-oxidation of benzaldehyde, produced by certain stains of lactic acid bacteria. In addition to the transformation of hippuric acid, these two sources (phenylalanine degradation, auto-oxidation of benzaldehyde) supply benzoic acid in cheese.