Enhancing gelatin-based films and coatings for food packaging: The role of novel technologies in extending shelf life

Gelatin-based films and coatings, derived from animal bones and skins such as beef, pork, and fish, have attracted remarkable attention as sustainable alternatives to petroleum-based plastics in food packaging due to their biodegradable, polymer-processable, and edible properties. Gelatin based films and coatings demonstrate promising features including transparency, elasticity, and moderate mechanical strength with high gas barrier properties. However, in comparison to synthetic films, gelatin-based films and coatings possess inferior water vapour barrier, mechanical, and thermal properties, which limit their practical application. To overcome these limitations, novel technologies have been explored to enhance the resulting physicochemical characteristics of gelatin-based films. This review focuses on the recent advancements in film modification techniques, including cold plasma, microwave, ultrasound, irradiation, UV treatment, ohmic heating, and high-pressure processing. These novel methods aim to tailor the interfacial and structural properties of gelatin films to meet the functional demands of food packaging applications. The application of novel processing technologies has led to significant improvements in the mechanical (e.g., Young's modulus, tensile strength), thermal, and surface properties of gelatin films, along with enhanced water vapour barrier characteristics and structural integrity. Evaluation of fundamental mechanisms across novel technologies reveals that free radical generation within gelatin polymers promotes covalent bonding and chemical structure modification depending on the applications. These cross-linkings occurring within the molecular structure alter the hydrophilic character of the gelatin polymer, thereby improving the weak properties of gelatin films and coatings. Among novel technologies, UV radiation has been particularly highlighted due to its heat-free nature, low cost, and environmentally friendly characteristics. UV-induced cross-linking in gelatin films is a noteworthy technology as it offers an alternative to traditional chemical cross-linking agents. Although the number of studies addressing this issue in the literature is limited, it is reported that film samples tested on food products after the application of novel technologies have the potential to extend the shelf life of food products and, accordingly, contribute to the improvement of packaging performance. Given these improvements, along with the sustainable, bio-based, and biodegradable nature of gelatin-based films, they present a promising eco-friendly alternative to petroleum-based plastic packaging, supporting the global transition toward sustainable materials in the food industry.