Plant extracts influence on growth of Aspergillus section Flavi toxigenic strains

TATIANA ALMEIDA; ÁGUIDA OLIVEIRA; KELLY KELLER; BEATRIZ MONTEIRO; LUIZ KELLER; LILIA CAVAGLIERI; CARLOS ROSA

Tulln, Viena, Austria

Congreso; Global discussion forum on:Worldwide Mycotoxin Reduction in Food and Feed Chains; 2009

International Society of Mycotoxicology

Several fungicides are being used today, but their security in foods is not fully stablished. The aim of this study was to evaluate some growth parameters to determine the influence of essential oils, ethanolic and aqueous extract of aromatic plants on Aspergillus section Flavi toxigenic strains. Essential oils were obtained by hydrodistillation and/or by hexanic extraction. A total of 40 plant extracts from basil, cinnamon, clove, cumin, fennel, marjoram, nutmeg, oregano, rosemary and spearmint were tested. First, a wide screening using diffusion method in agar was assayed to identify promising antifungal plant extracts. Essential oils were most effective than aqueous and ethanolic extracts to control aflatoxigenic strains. Oregano (Origanum vulgare) and rosemary (Rosmarinus officinalis) essential oils demonstrated to be the best antifungal effect. Studies on growth rate and lag phase were carried out at concentrations of 0, 50, 100, 150, 300 and 600 ppm. Petri dishes containing malt extract agar plus essential oils were centrally inoculated with fungal strains separately (103 conidia/ml in soft agar) and incubated at 25°C for 10 days. Both tested fungal strains showed better results with oregano than rosemary ones and the concentration of 600 ppm exert the best inhibition. For A. flavus, the growth rate observed at 100 and 150 ppm were statistically similar. Aspergillus parasiticus showed identical results in 50 and 100 ppm. Rosemary essential oil studies showed similar results than those found in the control group (5.3mm/day in both strains). A. flavus only showed statistical difference at 300 ppm. Lag phase analyses showed better results with oregano essential oil at 600 ppm (89 h for A. parasiticus and 72 h for A. flavus). On the other hand, rosemary essential oil showed 36 h lag phase at 600 ppm when A. parasiticus was studied, while A. flavus showed results statistically similar to control. These results prove that growth inhibition of Aspergillus section Flavi was achieved by the addition of essential oils, consequently it has relevance the search for new ways of fungal food contamination control. Future research to find solutions to mycotoxicoses is in advance.