195: Development of a Rosemary Oil-Incorporated, L-Arginine-Crosslinked Carboxymethyl Cellulose Antimicrobial Edible Coating Against Listeria Monocytogenes and Escherichia Coli

Introduction

The growing demand for environmentally sustainable food preservation methods has fueled interest in developing edible coatings with antimicrobial properties. Amino acid-polysaccharide hybrid biodegradable coating materials offer a stable structure for incorporating bioactive compounds. This study aims to develop a rosemary oil-incorporated, LA-CMC antimicrobial edible coating targeting Listeria monocytogenes and Escherichia coli.

Methods

The LA-CMC solution was prepared by dissolving 0.5 g of CMC in 100 mL of deionized water at 70°C, stirring at 400 rpm until clump-free. L-arginine (0.25 g) was added, and heated to 90–100°C and stirred for 1 hour before cooling to 25 ± 1°C. Tween 80 (1–5% v/v) was incorporated and stirred at 400 rpm for 15 minutes, followed by the addition of rosemary oil (1.5–4.5% v/v) and ultrasonication at 20 kHz, 80% amplitude, for 5–25 minutes. Response surface methodology was used to optimize rosemary oil (RO), Tween 80 (T-80), and ultrasound treatment time (UST), with inhibition zones of Listeria innocua and Escherichia coli determined via disc diffusion assay, and coating stability assessed gravimetrically as dependent variables. Data were fitted to a second-order polynomial equation, and optimal conditions were identified using the desirability function. The coating solution was analyzed for rheology.

Results

The quadratic model (response surface methodology) demonstrated significant predictive capability (p<0.01) for all responses, with R² values 79.27% for Listeria innocua, 87.95% for Escherichia coli, and 99.64% for coating stability. The optimal conditions were 4.4% (v/v) RO, 1.6% (v/v) T-80, and 5 minutes of UST, resulting in a desirability score of 0.7139. Model validation showed close agreement between experimental values for inhibition zones of Listeria innocua (11.07 ± 0.92 mm), Escherichia coli (9.75 ± 0.83 mm), and stability (83.55 ± 1.03%). The model's predictions 11.24 mm for Listeria innocua, 10.38 mm for Escherichia coli, and 84.16% stability. The coating exhibited shear thinning flow behavior (n<1) at 25°C.

Significance

The rosemary oil-incorporated, LA-CMC antimicrobial edible coating demonstrated significant antimicrobial activity against Listeria innocua and Escherichia coli. This coating offers a promising preservation method for fresh produce, such as melons, which are known as carriers of these pathogens, playing a key role in foodborne outbreaks.

Authors: Chien-I Hsu, Tharindu Trishan Dapana Durage, Kaushalya Wickramasinghe, Mariel Benigno, Mario Melendez, Sathivel Subramaniam