The Use of Sodium Chloride for Determining Viable Mold Counts and Mold Flora in Foods

The incorporation of 7.5% NaCl into potato dextrose agar (PDA), a medium routinely used for determining viable mold counts in foods, was effective in inhibiting fast-growing "spreader" molds. Viable mold counts using PDA with and without 7.5% NaCl were determined for 361 test samples of 12 food types, including dry, fleshy and frozen fleshy products. Only PDA plus 7.5% NaCl effectively inhibited the spreaders; food type did not influence its effectiveness. Average viable mold counts were usually higher for the 12 food types on PDA containing NaCl. With few exceptions, NaCl did not inhibit nonspreaders; in some cases it enhanced detection of more species, including several mycotoxin producers.