Optimization of Whey Protein-Based Films Incorporating Foeniculum vulgare Mill. Essential Oil

Petroleum-based plastics used in food packaging are not biodegradable. They accumulate in the environment in large amounts, causing a decrease in soil fertility, jeopardizing marine habitats, and causing serious problems to human health. Whey protein has been studied for applications in food packaging, either because of its abundant availability or because it confers transparency, flexibility, and good barrier properties to packaging materials. Taking advantage of whey protein to produce new food packaging materials is a clear example of the so-called circular economy. The present work focuses on optimizing the formulation of whey protein concentrate-based films to enhance their general mechanical properties applying the Box–Behnken experimental design. Foeniculum vulgare Mill. (fennel) essential oil (EO) was incorporated into the optimized films, which were then further characterized. The incorporation of fennel EO in the films leads to a significant increase (p < 0.05) in peak elongation (from 14.03 to 31.61%) and tensile index (from 0.40 to 0.50 N.m/g). The optimized whey protein films were yellowish and very transparent (>90%). The results of the bioactive activities of the optimized films showed their ability to be applied as active materials for food packaging to improve the shelf-life of food products and also to prevent foodborne diseases associated with the growth of pathogenic microorganisms.