Aspergillus flavus growth response to cinnamon extract and sodium benzoate mixtures

The effects of selected combinations of cinnamon extract (CE, 0, 50, 100, 200, 400 or 800 ppm) and sodium benzoate (NaB, 0, 12.5, 25, 50, 100, 200, 400 or 800 ppm) on the growth response of Aspergillus flavus inoculated on potato-dextrose agar (PDA) adjusted to 0.98 aw and pH 3.5 or 4.5 were evaluated for 30 days. Minimal inhibitory concentrations (MIC) were determined, transformed into fractional inhibitory concentrations (FIC) and a FICindex was computed. Cinnamon extract MIC was 200 ppm and not affected by pH, whereas for NaB a pH reduction from 4.5 to 3.5 reduced the MIC from 800 to 400 ppm. At pH 3.5 additive mixtures included 200 ppm of NaB, whereas at pH 4.5 these mixtures exhibited a synergic effect (FICindex = 0.75). Mixtures of CE and NaB are promising antifungal agents.