Effect of water activity and temperature on growth of ochratoxigenic strains of Aspergillus carbonarius isolated from Argentinean dried vine fruits

Aspergillus carbonarius is an ochratoxin A (OTA) producing fungus, predominantly responsible for the production of this mycotoxin in grapes, wine and dried vine fruits. The objective of this study was to determine the in vitro effects of water activity (aw, 0.80–0.95) and temperature (15–35 °C) on lag phase extension and radial growth rate of a cocktail inoculum of four strains of A. carbonarius. The maximum growth rate was observed at 0.95 aw and 30 °C (17.46 mm day− 1). In general, growth rates increased with the increment of aw. No growth was observed at aw below 0.85. For all aw levels tested the highest growth rate was detected at 30 °C. At 15 °C growth only occurred at the higher aw levels evaluated (0.925 and 0.95) at a growth rate of 3.82 and 5.57 mm day− 1 respectively. The shortest lag phase (0.26 days) was found at 0.925 aw and 35 °C. At marginal conditions of aw and temperature the lag phases increased, being the highest registered at 20 °C and 0.89 aw (33.7 days). The pattern of effects of environmental factors on growth was similar among Argentinean A. carbonarius strains and those from several European countries, Israel and Australia.