Effect of butylatedhydroxyanisole on ochratoxin A production by Aspergillus section Nigri on peanut grains.

BARBERIS C.L.,; FERNANDEZ JURI M. G.,; DALCERO A.M.; MAGNOLI A.P.,

Córdoba, Argentina

Congreso; VI Congreso Argentino de Microbiología General; 2009

Peanut (Arachis hypogaea L.) is one of the most important agricultural products in the Argentinean economy. In centre-south region of Córdoba province, is produced about 94% of the national production. Each year, an important percentage of the peanut total production is left outside the external market due to fungal disease at the post-harvest stage and mycotoxins contamination. Ochratoxin A (OTA) is one of the most important fungal toxic metabolite of worldwide concern for human and animal health, due to its implication in a diverse range of toxicological effects, including renal toxicity, mutagenicity, teratogenicity and immunotoxicity.The control of environmental factors in storage stage as water activity (aW) and temperature could prevent Aspergillus section Nigri growth and OTA production in several agricultural products. Previous studies demonstrated that this antioxidant could control fungal growth, fumonisin (FBs) and aflatoxin (AFs) production on natural substrates.The aim of the present study was to evaluate the effect of one of the best food grade antioxidant, butylatedhydroxyanisole on i) the lag phase to growth, ii) growth rates and iii) ochratoxin A (OTA) production by Aspergillus niger aggregate strains under different environmental conditions on peanut grains. A. niger aggregate strain (RCP191) and A. carbonarius (RCPG) were evaluated. Irradiated peanut grains (7 kGy) were rehydrated to 0.980, 0.950 and 0.930 aW. The antioxidant 2,3-ter-butil-4-hidroxianisol (BHA) were added to the irradiated grains to obtain the required concentrations (1, 5, 10 and 20 mmol g-1). Peanut grains were inoculated centrally with 5 µl of spore suspensions (1 x 106 spores ml-1) and incubated at 18 and 25°C for 30 days. Growth parameters and OTA concentration were determined. Ochratoxin A extraction was carried out using a clean up column (MycoSep ®229 Ochra column, MFC, Romer Labs®, Inc., MO., USA) and detected by HPLC. The antioxidant BHA at 5, 10 and 20 mmol g-1 completely inhibited OTA production at 0.93 and 0.95 aW at 18ºC for A. carbonarius strain, whereas for A. niger aggregate strain this fact was observed only at 0.95 aW and at the same temperature. However, a significant reduction in OTA production was observed at this temperature with 5 and 10 mmol g-1 and 0.93 aW. Toxin production at 25ºC showed a different pattern that observed at 18ºC. In general at 25ºC BHA was ineffective to reduce OTA production in all conditions assayed. The use of antioxidants could be an alternative to control ochratoxigenic fungi in peanut grains during storage before they are destined to internal and external market and industrialized.