Title : Chlorophyllin-based photosensitization for microbial control of fresh produce
Despite tremendous progress in biomedical science, the number of reported food-borne diseases continues to rise. Health experts estimate that every year food-borne illnesses in USA cost 86 billion dollars. Obviously, existing antibacterial technologies for microbial control of foods are not enough effective. Photosensitization is a treatment involving the interaction of the two non-toxic factors, photosensitizer and light, which in the presence of oxygen results in the destruction of the target cell without leakage of harmful by-products in the environment. According to our results, chlorophyllin (food additive E140) exhibits perfect photosensitizing properties. After excitation with light (405 nm) it inactivates food pathogens, their spores and biofilms, yeasts/microfungi. ROS-induced oxidative stress and following membrane damage was the main reason of photosensitization- based inactivation of microorganisms. Afterwards we applied photosensitization for microbial control of fresh produce. Obtained results indicate that this treatment significantly (2-3 log CFU/g) reduces microbial load on fruits (strawberries, apricots, plums), vegetables (cauliflower, cucumber, lettuce, basil) and sprouts without thermal effects on food matrix. Moreover, this treatment extended the shelf-life of treated produce by 2-4 days what is economically very important. No reduction of nutritional value (antioxidant activity, chlorophyll content) or organoleptic properties (color, texture, taste) of treated produce has been observed. In order to decontaminate fresh produce from Gram (+) and Gram (-) pathogens in uniform way, chlorophyllin was conjugated with chitosan. Obtained data reveal that such photoactivated conjugate is very effective against all pathogens and can be applied for coating of fresh produce. Therefore, a photosensitization phenomenon might open a new avenue for the development of non-thermal, effective and ecologically friendly antimicrobial technology for preservation of fresh produce.