Natural additives as functional modifiers in protein–polysaccharide films for food and biomedical applications: A systematic review

Background Growing environmental concerns caused by synthetic polymers and the increasing demand for sustainable, biodegradable materials have led to the expanded use of protein–polysaccharide composite films in food packaging and biomedical applications. Despite their biological advantages, pure protein- or polysaccharide-based films often exhibit limitations in mechanical strength, moisture resistance, and barrier performance. In recent years, the incorporation of natural additives derived from plant, mineral, or biological sources has emerged as an effective strategy to enhance the performance of these films. Such additives can improve tensile strength, flexibility, thermal stability, antioxidant capacity, and antimicrobial activity through hydrogen bonding, electrostatic interactions, or covalent linkages. Objective The objective of this systematic review is to provide a comprehensive overview of recent advancements in the development of protein–polysaccharide films reinforced with natural additives. This paper analyzes the functional mechanisms, types of additives, natural sources, and the effects of these on the physical and biological characteristics of protein–polysaccharide films. Methods This systematic review involved a comprehensive literature search that described protein–polysaccharide films and their properties, natural additives (including plant extracts, essential oils, polyphenols, bio-based nano-fillers, peptides, and mineral fillers), and applications involving food packaging or biomedical uses were included. Results The studies in this literature review provided strong evidence to support the efficacy of natural additive ingredients in comparison to synthetic alternatives. These natural additives have been proven to be effective at improving the following mechanical properties: tensile strength; thermal stability; moisture resistance; antioxidant activity; antimicrobial properties; and biocompatibility. The findings indicate that integrating natural additives can bridge the gap between biostability and industrial performance. Conclusion Protein–polysaccharide composite films functionalized with natural additives represent a promising class of sustainable materials with significant potential in food packaging and biomedical applications. The development of this generation of composite films could mark a significant milestone in achieving sustainable packaging and smart scaffolds in both the food and medical industries. Overall, the development of multifunctional films offers a promising pathway to produce active, intelligent, and eco-friendly materials for the food and biomedical industries.