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The aim of the present study was to prepare whey protein isolate (WPI)‐based films containing Citrus sinensis peel essential oil (CSEO) loaded emulsions and nanoemulsions (2.5% and 5% of WPI), as an active packaging system. The fabricated films were characterized by Fourier transform infrared spectroscopy, Filed Emission Scanning Electron Microscopy, X‐ray diffraction, and tensile analyses. The obtained results approved the appropriate interactions between WPI matrix and CSEO emulsion and nanoemulsion due to their good compatibility. The incorporation of nanoemulsion significantly improved the water barrier properties of the film samples. Additionally, the antioxidant and antimicrobial activities of the CSEO nanoemulsion incorporated films were significantly higher than those of the emulsion incorporated films. As a result, the developed active WPI‐based film containing CSEO nanoemulsion can be suggested as a suitable food packaging system for the preservation of foodstuffs against oxidation and microbial spoilage. Practical applications Biodegradable active packaging is an alternative new technology for preserving the quality and safety of food products, often achieved by the incorporation of antibacterial and antioxidant ingredients into the biopolymer‐based packaging system. The application of whey protein isolate‐based active films containing orange peel essential oil nanoemulsions, as an active packaging system, would be a positive step in improving shelf life and quality of foodstuffs.

The aim of this research was synthesizing of bacterial cellulose (BC) nanohybrids by incorporation of CuO‐NPs and evaluation of their ability in the removing of microbial, heavy metals, and dyes pollutants from water. CuO‐BC nanohybrids were synthesized by two in situ (sonochemical and precipitation) methods and compared with ex situ synthesized nanohybrid. FE‐SEM images revealed that the growth of CuO‐NPs in the sonochemically synthesized in situ substrate is better. The ex situ nanohybrid had the highest loading capacity (27.17 μg/cm2) but the migration of CuO‐NPs from this substrate was higher than in situ ones. According to antimicrobial tests, 80% and 90% of initial population of E. coli and S. aureus, respectively, were removed after 6 hr contact of substrates with water. The potential of the substrates in the adsorption of lead and arsenic was about 60% after 24 hr. About 75% of methylene blue and methyl orange dyes were adsorbed into substrates after 6 hr. CuO doped substrates had the photocatalytic activity and caused to decrease the oxygen content about 4%–7% during 6 hr. In general, the reusability of ex situ synthesized substrate was lower than in situ nanohybrids. Sonochemically synthesized substrate was suggested as the best nanohybrid for water purification applications in terms of morphological properties and reusability. Practitioner points CuO‐BC nanohybrids were prepared by in‐situ and ex‐situ methods. Well distribution of NPs and slower release was achieved by in‐situ methods. Antimicrobial and photocatalytic activity of ex‐situ nanohybrid was higher than in‐situ ones. Dyes and heavy metals were removed successfully with nanohybrid substrates. Sonochemical in‐situ nanohybrid exhibited the best water purification performance.