New horizons in microbiological food safety: Photodynamic Decontamination based on a curcumin derivative

Outbreaks of foodborne diseases are regularly reported worldwide. In particular, uncooked plant food is considered risky in terms of microbiological safety. Food is also the most important transmission route for resistant microorganisms from animals to humans. Photodynamic Decontamination (PDc) of foodstuff was recently introduced as a novel approach for increasing microbiological food safety. We investigated the efficiency of PDc on plant food with different geometries (flat, spherical and complex) using a two-dimensional LED array as a light source (435 nm, 33.8 J cm −2 ) and the cationic curcumin derivative SACUR-3 as a photosensitiser. A photoantibacterial effect (>3 log 10 CFU reduction) was achieved on all flat substrates (slices of cucumber, tomato and lettuce) with 10 pM, 50 pM or 100 pM SACUR-3. The maximal photokilling with a relative inactivation of 5.6log 10 was measured on lettuce using 50 pM of the photoactive compound. Phototreatment of non-germinated fenugreek seeds and mung beans was successful if the spherical objects were rotated while under illumination (antibacterial effect at 100 pM SACUR-3). The decontamination of mung bean germlings with a more complex geometry using the PDc approach was inefective with the two-dimensional light source. In conclusion, PDc based on the cationic curcumin derivative SACUR-3 is very efective at improving the microbiological safety of plant food with a flat or spherical geometry. More complex objects will require the development of novel illumination devices.