Development and Optimization of UV-C Treated Chitosan-Gallic Acid Edible Coating on Salmonella Typhimurium Inactivation

Abstract

Foodborne pathogens such as Salmonella pose a significant threat to public health and an economic burden to manufacturers. Edible coating solutions, made from edible materials, have emerged as an alternative approach in controlling food spoilage as well as extending food shelf life. This study aimed to develop and optimize a novel edible coating solution based on UV-C treated chitosan (CH) and gallic acid (GA) to inactivate Salmonella Typhimurium. A Box–Behnken Design was used to generate formulations by varying chitosan, gallic acid concentrations, and pH. The coatings underwent UV-C treatment, and their microbial inactivation and water vapor permeability were analyzed. One formulation (higher response condition) (1.5% chitosan, 1% gallic acid, pH 3.4) achieved a 5.6 log CFU reduction in S. Typhimurium in planktonic form and exhibited superior moisture barrier properties (WVP of 9.57 × 10⁻¹² g/s.m.Pa). Later, this higher response coating formulation inactivated over 6.5 log CFU of S. Typhimurium on agar media surface, and on cherry tomatoes and pork, it reduced S. Typhimurium counts by 3.4 and 1.4 log CFU, respectively, demonstrating the potential for food industry applications. The combined effect of chitosan, gallic acid, and pH played a major role in inactivating Salmonella in planktonic and on food surfaces.