ALLYL ISOTHIOCYANATE AS A POTENTIAL ANTIMICROBIAL COMPOUND AGAINST MYCOTOXIGENIC Aspergillus SPECIES ON GREEN COFFEE

During the crop and storage, green coffee are susceptible to fungi contamination, mainly by the Aspergillus species, and may produce mycotoxins, which present a risk to the health of humans and animals. Among them, ochratoxin A (OTA) is frequently detected in coffee and it is classified as possibly carcinogenic to humans. The aim of this study was to evaluate allyl isothiocyanate (AITC) in vitro against Aspergillus species OTA producers found on green coffee. Three strains of Aspergillus (Aspergillus ochraceus, A. lacticoffeatus and A. sclerotioniger) were tested to evaluate the minimum inhibitory concentration (MIC) and halo inhibition with different levels of AITC (MIC- 7.8; 15.6; 31.2; 62.5 and 125 μL/L; halo inhibition- 0.03; 0.06; 0.12; 0.25 and 0.50 μL/L at gaseous phase). The visual growth of 50% was considered the MIC value. The MIC was 62.50 μL/L for A. ochraceus, 31.25 μL/L for A. lacticoffeatus and 15.63 μL/L for A. scleriotioniger. The halo inhibition test was evaluated by the inoculation of 10 μL spore solution at 104 spores/mL in PDA plates, and, conditioned in hermetic bottles with gaseous AITC (0.03 to 0.5 μL/L), incubated for 5 days at 25 ºC. After incubation, the halos were measured with a pachymeter and compared to the control (without AITC treatment). The halo was completely inhibited at 0.25 μL/L for the three strains. These results displayed a potential use of AITC to inhibit species of Aspergillus ocratoxin A producers at low doses. Therefore, AITC was efficient to inhibit mold growth during in vitro tests, especially when applied in gaseous form. Gaseous AITC could be used to reduce Aspergillus species and ochratoxin A production.