Effect of Photosensitization on Inactivation of Aspergillus flavus in Maize ^†

Abstract

Mycotoxins are naturally occurring toxins produced by certain types of fungi that contaminate food and feed, posing serious health risks to human and livestock. Photosensitization is a light-based technique, which has emerged as a novel and promising green technology to control microbial growth in food and feed. This study aimed to evaluate the effect of solvent medium including ethanol (EtOH), 50% (v/v) propylene glycol (PG), 20 % (v/v) tween 20 (TW-20), and 20 % (v/v) tween 80 (TW-80), on curcumin-mediated photosensitization to inactivate Aspergillus flavus spores in vitro and on the surface of yellow and white maize kernel and flour. Results showed a reduction in the phototoxic activity of curcumin in TW-20 and TW-80. However, curcumin-based photosensitization using EtOH and PG as solvents led to a significant decrease in the colony forming ability of A. flavus spores in vitro, up to 2.04 and 3.33 log colony-forming unit (CFU), respectively. Interestingly, fungal growth was delayed in photosensitized maize kernel and flour for 14 and 7 days, respectively, which were stored at 25 °C. Consequently, no Aflatoxin B1 (AFB1) was detected in maize kernels after 20 days of storage at 25 °C, whereas accumulation of the toxin was reduced by 91% in photosensitized flour. Thus, photosensitization showed to be a potential alternative to reduce A. flavus contamination on maize kernel and flour, giving rise to low concentrations of AFB1. This technique has the potential for use in feed applications resulting in the reduction of post-harvest losses in maize.