Controlled Release of β-CD-Encapsulated Thyme Essential Oil from Whey Protein Edible Packaging

Abstract

Whey edible films (EFs) functionalized with essential oils have a high potential to be used on various foods due to their antimicrobial and antioxidant activities. Encapsulation is applied for a better retention of volatiles in EFs; however, the functional properties of EFs are modified. The properties of EFs containing thyme essential oil (TEO) encapsulated by co-precipitation in β-CD, developed in three formulae, with inclusion complexes (EF/IC1, EF/IC2, and EF/IC3, respectively) in 15:85, 26:74, and 35:65 mass ratios were studied. Thymol is the main volatile in the ICs with TEO/β-CD (50%–60% of the total volatiles). In comparison with EF/TEO, all three formulae with EF/ICs had better, but similar, WVPs (p > 0.05). The EF/IC2 displayed a different FTIR profile than EF/IC1 and EF/IC3, suggesting a smaller number of free functional groups. The EF/IC2 showed better transparency in comparison with EF/IC1 and EF/IC3. All EF/ICs moderately inhibited R. glutinis, with the strongest activity registered by EF/IC3 (p < 0.05), but did not inhibit G. candidum, while showing a strong antibacterial activity against B. cereus. All EF/ICs inhibited 65%–70% of the total free radicals. The EF/ICs ensured a gradual release of VOCs in food simulants, with a higher rate in 95% ethanol than in water. These results have demonstrated the properties of EF/ICs with TEO/β-CD as bioactive packaging systems for foods.