Reducing Pseudomonas fluorescens in milk through photodynamic inactivation using riboflavin and curcumin with 450 nm blue light-emitting diode

This study determined the phototoxic potential of riboflavin (RIB) and curcumin (CUR) against Pseudomonas fluorescens (P. fluorescens) in vitro and in fluid milk using factorial arrangements. Photodamage was investigated by transmission electron microscopy. The milk was illuminated by thin layers or constant agitation to verify its efficiency in practical industrial situations, as well as to monitor changes in food quality. High loads of P. fluorescens were photoinactivated through cell membrane disruption with extravasation of intracellular content. CUR was more efficient than RIB. The milky matrix hinders the absorption of light by photosensitising molecules (PSs), but there was still a reduction in the number of bacteria. The different lighting methods were not significant. The macronutrient composition and protein oxidation levels were not altered. Light induced lipid peroxidation. PSs changed the milk's colour. Therefore, photodynamic inactivation (PDI) is an alternative to reduce contaminating microorganisms in food while preserving quality.