Fungi-derived chitosan as an emulsion stabilizer for the encapsulation of bioactives

Abstract

In recent years, an increasing number of industries have been embracing a more sustainable and environmentally friendly approach by adopting materials that are more eco-conscious compared to their previous choices. The food industry is at the forefront of this movement, striving to introduce novel biocompatible and biodegradable materials that can serve various purposes, such as protection agents, supplements, and carriers. Fungal chitosan (FC), has numerous characteristics, such as the lack of allergen animal proteins, consistency in physicochemical characteristics and easy production, while at the same time being an excellent emulsifier. This is why it has gained significant attention from scientists for various applications. In this study, FC particles were formulated using the pH-shifting method, while emulsions were prepared through high-shear homogenization. The emulsions were examined both macroscopically and microscopically. Their droplet size was determined using Static Light Scattering, revealing an average size of approximately 75 µm. Furthermore, α-tocopherol or squalene was successfully encapsulated in these emulsions. Cryogenic Scanning Electron Microscopy (Cryo-SEM) was utilized to visualize the surface of the droplets, and Confocal Laser Scanning Microscopy allowed for the observation of the droplet core. To assess their antioxidant properties, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetric assay was employed. Additionally, their antimicrobial potency was evaluated. In the presence of the bioactive compounds, both emulsions exhibited scavenging activity against the DPPH radical, with emulsions loaded with α-tocopherol demonstrating the highest antioxidant capacity. Most importantly, all tested samples led to a reduction in the bacterial population of pathogen target bacteria Escherichia coli C1845 (E. coli) and Staphylococcus aureus DSM 21705 (S. aureus) proving they possess antimicrobial properties.