Rice husk and lemongrass-derived eco-enzymes as potential food contact surface disinfectants against biofilm-forming foodborne pathogens

This study aims to evaluate the rice husk (EE-R) and lemongrass (EE-L) derived-eco-enzymes (EE) as alternatives to chemical-based disinfectants. The EE-R and EE-L's antimicrobial activity were tested against Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus using a broth microdilution method. The antibiofilm activities of EE were determined using crystal violet staining. Lastly, the minimal contact time of EE for effectively reducing biofilm-forming pathogens (<25 CFU/mL) was assessed on various food contact surfaces (wood, glass, plastic, stainless steel, and marble). The results show that EE-R at 25-50% concentration significantly inhibited P. aeruginosa and S. aureus while reducing the initial biofilm formation by 61% and 58%, respectively. Contrarily, EE-L inhibited S. Typhimurium at 12.5-50% and P. aeruginosa at 25-50% concentration, with a strong preformed biofilm inhibition noticed for S. Typhimurium (70%). For the minimal contact time, EE-R superiorly inhibited P. aeruginosa (60 s) and S. aureus (120 s) on all contact surfaces, and contrarily, EE-L needed 120 s to reduce P. aeruginosa and S. Typhimurium. These outcomes were comparable to sodium hypochlorite (NaOCl-2.5%). The study's outcomes implicate the potential application of EE-R and EE-L as surface disinfectants against biofilm-forming bacteria, thus promoting safer food processing practices while minimising environmental impacts.