Active bio-packaging with PHBHHx-ZnO bionanocomposites: advancing food safety and shelf-life.

Food loss and waste remain major global challenges. Perishables like fish, fruits, and vegetables show the highest post-harvest losses. Conventional petroleum-based packaging offers limited preservation while adding long-term pollution, and recent assessments indicate that more than one billion tons of food were wasted in 2022, reinforcing the need for improved preservation strategies. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) films reinforced with ZnO nanoparticles provide flexibility, biodegradability, and reliable processing. ZnO increases mechanical stiffness and thermal stability, strengthens oxygen-barrier and antimicrobial functions, and delivers strong UV shielding. These combined properties define the active-preservation behavior of PHBHHx-ZnO films and support their relevance for chilled food systems. ZnO acts as a nucleating agent, with PHBHHx-ZnO films typically showing crystallinity in the 53-56% range without loss of flexibility. Studies with ZnO-enabled active films extend refrigerated shelf life. Storage periods of 6-8 days rise to 12-16 days in seafood models, with similar improvements for meat and dairy products. These gains arise from nanoparticle-polymer interactions that increase crystallinity, restrict polymer mobility, and stabilize film microstructures. PHBHHx-ZnO bionanocomposites offer a promising route toward safe, active, and sustainable packaging systems. This review outlines further directions, including migration-compliant ZnO placement, lower-impact ZnO preparation routes, and multifunctional designs aligned with more circular-economy goals.