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 cultu red dairy products and cheese. During fermentation, benzoic acid is pr oduced from hippuric acid a component of milk naturally present at con centrations of up to 50 mg/kg. In smear-ripened cheese, however, highe r benzoic acid concentrations have often been measured on the surface or even inside such cheeses. A second metabolic pathway has been propo sed: during ripening, an additional quantity of benzoic acid originate s from phenylalanine degradation, with beta-phenyl-propionic (hydrocin namic) acid and cinnamic acid as intermediate products. Acetophenone i s 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 form ation during cheese ripening, and the simultaneous production of ammon ia resulting from deamination support the validity of this second meta bolic pathway. A third way could be the auto-oxidation of benzaldehyde , produced by certain stains of lactic acid bacteria. In addition to t he transformation of hippuric acid, these two sources (phenylalanine d egradation, auto-oxidation of benzaldehyde) supply benzoic acid in che ese.