Leveraging pH-dependent coacervation process for preparing sustainable biomimetic colloidal suspensions

In recent years, the demand for meat processing has grown significantly, driven by population growth and rising consumer needs. Canadian meat processing plants are striving to meet these demands whilst ensuring compliance with environmental regulations to maintain safe, sustainable, and cost-effective practices. Herein, pH-responsive chitosan-carboxymethylcellulose (CTS-CMC) coacervate hydrocolloids were developed as stable colloidal suspensions of aggregated soft polyelectrolyte complexes (PECs) for potential use as protective surface coatings. CTS-CMC hydrocolloids were prepared via aqueous ionic gelation and systematically tuned by pH, CTS:CMC mass ratio, and biopolymer concentration. Colloidal stability and self-assembly behavior were characterized using turbidity, particle size distribution, zeta potential, viscosity measurements, and transmission electron microscopy. We hypothesize that, by reducing hydrophobic interactions between the coating and meat surfaces, these hydrocolloid systems may decrease adhesion and antimicrobial activity at solid interfaces during food processing. Antibacterial performance against Escherichia coli and Staphylococcus aureus was evaluated using minimum inhibitory concentration (MIC) and disc diffusion method, revealing strong pH-dependent antimicrobial activity in CTS-rich suspensions, especially at pH 5 with 4:1 CTS:CMC ratios with MIC values of 0.91 ± 0.24 mg/mL for E. coli and 0.38 ± 0.17 mg/mL for S. aureus . These positively charged hydrocolloids likely contribute to antibacterial activity by interacting with and entrapping bacterial cells within the colloidal aggregates, enhancing contact and inhibiting bacterial growth. Overall, this study demonstrates that CTS-CMC coacervate hydrocolloids offer a versatile, biodegradable platform with tunable colloidal stability, rheology, and antimicrobial functionality, supporting their potential application as sustainable hydrocolloid coatings in food-processing environments.