Recent Advances in the Development of Active and Intelligent Packaging Films Using Fruit Peel Powders.

Fruit peels, a primary fruit processing by-product, are rich in biodegradable polymers (e.g., dietary fibers and proteins) and bioactive substances (e.g., polyphenols, essential oils, and pigments) that are suitable for producing active and intelligent packaging films. In recent years, there is a new trend to utilize fruit peels in the form of powders for film production, which aligns with circular economy principles. In general, fruit peel powders (FPPs) can function as rigid fillers and the polymer matrix in packaging films, forming FPP-filled and FPP-based films, respectively. These two film types exhibit distinct characteristics: FPP-filled films typically have a compact structure with strong molecular interactions, leading to superior mechanical and barrier properties. Conversely, FPP-based films often display a cracked structure with weaker molecular interactions, resulting in inferior mechanical and barrier properties. Despite these differences, both film types demonstrate excellent antioxidant and antimicrobial activities, pH sensitivity, and biodegradability, as well as considerable promise for active and intelligent packaging. This review comprehensively summarizes the preparation methods, structural characteristics, physical and functional properties, and active and intelligent packaging potential of both film types. It also features a multi-dimensional comparison of FPP-filled and FPP-based films' performance and a discussion of their current challenges and future directions.