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United States Department of Agriculture

Agricultural Research Service

Research Project: Pre and Postharvest Treatment of Tropical and Other Commodities for Quarantine Security, Quality Maintenance, and Value Enhancement

Location: Tropical Crop and Commodity Protection Research

Title: Radiosensitization of Aspergillus niger and Penicillium chrysogenum using basil essential oil and ionizing radiation for food decontamination.

Authors
item Houssain, F. -
item Follett, Peter
item Senoussi, C. -
item Lacroix, M. -

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 15, 2014
Publication Date: May 2, 2014
Citation: Houssain, F., Follett, P.A., Senoussi, C., Lacroix, M. 2014. Radiosensitization of Aspergillus niger and Penicillium chrysogenum using basil essential oil and ionizing radiation for food decontamination. Food Control. 45:156-162.

Interpretive Summary: Fungi can cause postharvest losses in stored rice. Fumigation with plant essential oils or irradiation treatment can reduce losses. The antifungal activity of the basil oil in combination with ionising radiation was investigated to determine if basil oil caused radiosensitization . Radiosensitization of A.niger and P. chrysogenum in the presence of 1% or 2% basil oil was evaluated in vitro and in packaged rice. Results showed a MIC of 0.1% basil oil for both fungal species after 48 hr. Combined treatments of basil oil and irradiation showed increased efficacy with increasing basil oil concentration. The in vitro D10 value was 0.40 and 0.31 kGy for 1 and 2% of basil oil respectively against A.niger, and 0.44 and 0.33 kGy for 1 and 2% of basil oil respectively for P. chrysogenum. A significant decrease in D10 was observed as basil oil concentration increased to 2% as compared to control for both fungi indicating an increase of the relative sensitivity. In inoculated rice, D10 values for controls (sample without basil oil) were 0.67 and 0.63 kGy for A.niger and P.chrysogenum respectively, and decreased as the concentration of basil oil increased. For A.niger, 2% basil oil alone caused a 0.42 to 1.18 log reduction in mold during 14 days in packaged rice, whereas treatment with 2 kGy radiation dose alone caused a 2.18 log reduction. Combining the two treatments resulted in a 4.69 log reduction during the same time period. For P.chrysogenum, 2% basil oil alone caused a 0.76 log reduction mold during 14 days in packaged rice, whereas a 2 kGy of radiation dose caused a 2.41 log reduction. Combining the two treatments resulted in a 4.09 log reduction in P.chysogenum after day 1. These findings demonstrate that basil oil has potential as a natural antifungal agent to control mold growth in rice, and can also serve as an agent to increase the relative radiosensitivity of A.niger and P. chrysogenum.

Technical Abstract: The Minimum Inhibitory Concentration (MIC) of basil oil, was determined for two pathogenic fungi of rice, Aspergillus niger and Penicillium chrysogenum. The antifungal activity of the basil oil in combination with ionising radiation was then investigated to determine if basil oil caused radiosensitization . Radiosensitization of A.niger and P.chrysogenum in the presence of 1% or 2% basil oil was evaluated in vitro and in packaged rice. Results showed a MIC of 0.1% basil oil for both fungal species after 48 hr. Combined treatments of basil oil and irradiation showed increased efficacy with increasing basil oil concentration. The in vitro D10 value was 0.40 and 0.31 kGy for 1 and 2% of basil oil respectively against A.niger, and 0.44 and 0.33 kGy for 1 and 2% of basil oil respectively for P.chrysogenum. A significant decrease in D10 was observed as basil oil concentration increased to 2% as compared to control for both fungi indicating an increase of the relative sensitivity. In inoculated rice, D10 values for controls (sample without basil oil) were 0.67 and 0.63 kGy for A. niger and P.chrysogenum respectively, and decreased as the concentration of basil oil increased. For A.niger, 2% basil oil alone caused a 0.42 to 1.18 log reduction in mold during 14 days in packaged rice, whereas treatment with 2 kGy radiation dose alone caused a 2.18 log reduction. Combining the two treatments resulted in a 4.69 log reduction during the same time period. For P.chrysogenum, 2% basil oil alone caused a 0.76 log reduction mold during 14 days in packaged rice, whereas a 2 kGy of radiation dose caused a 2.41 log reduction. Combining the two treatments resulted in a 4.09 log reduction in P. chysogenum after day 1. These findings demonstrate that basil oil has the potential as a natural antifungal agent to control mold growth in rice, and can also serve as an agent to increase the relative radiosensitivity of A. niger and P.chrysogenum.

Last Modified: 11/28/2014
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