Controlling microbial contamination in foods using effective clean and green technologies is important in producing food with less contaminants. This study investigates the effect of photosensitization treatment using naturally occurring curcumin on inactivating Aspergillus flavus spores on peanuts. Light dosages of 76.4 J/cm² and 114.5 J/cm² at 420 nm were employed in combination with curcumin concentrations from 25 to 100 μM. The inactivation efficiency of the treatment towards spores in suspension achieved a maximum 2 log CFU/mL reduction in viable spores with 75 μM of curcumin at a light dosage of 114.5 J/cm² (p < 0.05). The in vivo study was then designed using the optimum conditions from the in vitro experiment. The photosensitization treatment at three different curcumin concentrations (50, 75, 100 μM) extended the shelf-life of raw peanuts by 7 days when treated with 75 μM of curcumin combined with a 114.5 J/cm² light dosage and stored at 25 °C. The treatment effectively reduced average levels of aflatoxin B1 (AF-B1) on peanuts stored for 7 days at 25 °C from 9.65 mg/kg of untreated samples to 0.007 and 0.006 mg/kg for 75 and 100 μM curcumin (p < 0.05) respectively. The results show the potential use of curcumin-based photosensitization treatment in inactivating fungal growth and reducing AF-B1 concentration on raw peanuts.

The aim of this study was to investigate the efficiency of curcumin-based photosensitization (CUR-PS) in inactivating Aspergillus flavus spores and in turn reducing the aflatoxin B1 production and extending the shelf-life of raw peanuts. The inoculated peanuts with A. flavus spores were illuminated for 15 min at 420 nm (Xenon Arc light source) using three different curcumin concentrations of 50, 75, and 100 μM. The highest reduction in A. flavus spores on peanuts (1.7 log CFU) was obtained by 50 μM curcumin (p > 0.05). Interestingly, shelf life of treated peanuts with 75 μM curcumin was extended by 7 days. In order to evaluate the influence of CUR-PS treatment on aflatoxin B1 generation, treated and untreated peanuts were analysed after 20 days of storage 25 °C. Results showed that the average level of aflatoxin B1 in untreated (control) peanuts was 800 mg/kg, while light treatment of peanuts reduced the aflatoxin production to the level of 296 mg/kg. A significant reduction in aflatoxin production was observed in curcumin (75 μM) treated peanuts, where 38.3 and 41.1 mg/kg aflatoxin were detected in illuminated and not-illuminated peanuts, respectively. Moreover, 59.2 and 58.1 mg/kg aflatoxin were detected in CUR-PS treated peanuts with 50 and 100 μM curcumin, respectively. However, not illuminating curcumin treated peanuts with 50 and 100 μM showed higher levels of aflatoxin, 108.8 and 105.3 mg/kg, respectively (p > 0.05). This study demonstrated the efficiency of CUR-PS treatment as a safe and green technology to control fungal growth and mycotoxin production in agro-food sector.