Fungal decontamination and enhancement of shelf life of edible split beans of wild legume Canavalia maritima by the electron beam irradiation

• Ripened split beans of coastal sand dune legume Canavalia maritima serve as nutritional source of coastal dwellers of Southwest India.
• Dry split beans were electron beam irradiated (0, 2.5, 5, 10, 15 kGy) to control storage molds.
• Unirradiated split beans consist of Aspergillus niger in the highest incidence (33–50%) followed by A. flavus (14–20%) and Penicillium chrysogenum (7–13%).
• Irradiation showed dose-dependent decrease in fungal contaminants and irradiated beans (10 and 15 kGy) devoid of aflatoxins (B1 and B2).
• Irradiated split beans (10 kGy) showed improved shelf life up to six months without deterioration under normal laboratory conditions.

Ripened split beans of the coastal sand dune wild legume Canavalia maritima serve as one of the traditional nutritional sources of the coastal dwellers in Southwest coast of India. Nine fungi were isolated from the unirradiated dry beans by plating on the potato dextrose agar medium. Toxigenic fungus Aspergillus niger showed the highest incidence (33–50%) followed by Aspergillus flavus (14–20%) and Penicillium chrysogenum (7–13%). Unirradiated dry beans and irradiated dry beans with electron beam doses 2.5, 5, 10 and 15 kGy were monitored for occurrence of fungal species and their incidence during 0, 3 and 6 months storage period under laboratory conditions. Irradiation resulted in dose-dependent decrease in fungal species (5–7, 4–6, 3–6 and 0 on irradiation at 0, 2.5, 5 and 10 or 15 kGy, respectively) as well as incidence (80–99, 19–46, 13–21 and 0%, respectively). Although aflatoxins (B1 and B2) were found below detectable level (<2 ng/g) in 0, 3 and 6 months stored unirradiated and irradiated beans (2.5 and 5 kGy), they were not present in beans irradiated with 10 and 15 kGy. In spite of occurrence of toxigenic fungus Aspergillus ochraceus in unirradiated and irradiated beans (2.5 and 5 kGy) stored for 3 and 6 months, the beans were devoid of ochratoxin-A. Electron beam irradiation dose 10 kGy could be recommended for fungal decontamination and improvement of shelf life of C. maritima ripened dry split beans.