Combinations of antimycotics to inhibit the growth of molds capable of producing 1,3-pentadiene

Some species of molds are capable of degrading sorbic acid to produce 1,3-pentadiene, a volatile compound with an unpleasant hydrocarbon-like odor. The effectiveness of reduced concentrations of sorbate, in combination with other antimycotics, to control the growth of these molds has not been described. We did a study to evaluate potassium sorbate, sodium benzoate, calcium propionate, disodium ethylenediaminetetraacetic acid (EDTA), and natamycin, alone and in combination, for their effectiveness in preventing the growth of five molds isolated from Parmesan cheese and a lemon-flavored drink subjectively judged to contain 1,3-pentadiene. Growth of Penicillium brevicompactum, Penicillium roqueforti, Paecilomyces variotii, Aspergillus niger, and Cephaloascus fragrans on model agar media containing Parmesan cheese (PRM agar) (pH 5.5) and lemon-flavored drink (LD agar) (pH 2.6) supplemented with antimycotics was studied. All molds grew well at 21 °C on PRM agar containing potassium sorbate (3500 μg/ml), calcium propionate (3000 μg/ml), or natamycin (20 μg/ml). Combinations of potassium sorbate (250–1000 μg/ml), calcium propionate (250–1000 μg/ml), and/or natamycin (10–18 μg/ml) greatly inhibited or prevented growth of molds on PRM agar, indicating their potential as preservative systems at pH values resulting in large percentages of the acids in dissociated forms. Three of the five molds grew on LD agar containing potassium sorbate or sodium benzoate at a concentration of 200 μg/ml. Growth did not occur within 70 days on LD agar containing EDTA (30 μg/ml) in combination with potassium sorbate and sodium benzoate at 50 and 175 μg/ml, respectively, or 175 and 50 μg/ml, respectively. Results of this study show that preservative systems containing a reduced concentration of potassium sorbate, in combination with other antimycotics, particularly natamycin, have potential for controlling the growth of molds thought to be capable of producing 1,3-pentadiene.