Reduction of biofilm and pathogenic microorganisms using curcumin-mediated photodynamic inactivation to prolong food shelf-life.

Pathogenic microbial contamination (bacteria and fungi) in food products during production poses a significant global health risk, leading to food waste, greenhouse gas emissions, and aesthetic and financial losses. Bacteria and fungi, by forming solid biofilms, enhance their resistance to antimicrobial agents, thereby increasing the potential for cross-contamination of food products. Curcumin molecule-mediated photodynamic inactivation (Cur-m-PDI) technology has shown promising results in sterilizing microbial contaminants and their biofilms, significantly contributing to food preservation without compromising quality. Photosensitizers (curcumin) absorb light, leading to a chemical reaction with oxygen and producing reactive oxygen species (ROS) that effectively reduce bacteria, fungi, and biofilms. The mechanism of microorganism inhibition is caused by exposure to ROS generated via the type 1 pathway involving electron transfer (such as O 2 • - , H 2 O 2 , -OH•, and other radicals), the type 2 pathway involving energy transfer (such as 1 O 2 ), secondary ROS, and weakening of antioxidant enzymes. The effectiveness of the inactivation of microorganisms is influenced by the concentration of curcumin, light (source type and energy density), oxygen availability, and duration of exposure. This article reviews the mechanism of reducing microbial food contamination and inhibiting their biofilms through Cur-m-PDI. It also highlights future directions, challenges, and considerations related to the effects of ROS in oxidizing food, the toxicity of PDI to living cells and tissues, conditions/types of food products, and the stability and degradation of curcumin.