Use of propyl paraben to control growth and ochratoxin A production by Aspergillus section Nigri species on peanut meal extract agar

This study was carried out to determine the efficacy of the phenolic antioxidant propyl paraben (PP) under different interacting water activity (aW) and temperature regimes on lag phase, growth rate and Ochratoxin A production by Aspergillus section Nigri strains. In this experiment six Aspergillus section Nigri strains were used. Peanut meal extract agar (PMEA) was prepared at 2%. The aW of the medium was adjusted to 0.995, 0.980 and 0.930, PP levels of 1, 5, 10 and 20 mmol/L were added to the basic medium. Plates were inoculated and incubated for 30 days at 18 and 25 °C. Lag phase (h) and radial growth rates (mm/day) were calculated. In control treatments, the lag phase increased and the growth rate decreased as aW reduced in all assayed strains. At all aW levels, when antioxidant concentrations increased the growth rate decreased. At 5, 10 and 20 mmol/L of PP the strains were not able to reach the exponential phase and completely inhibited fungal growth and OTA production regardless of aW used in all the evaluated strains.