Physicochemical, Antioxidant and Food‐Freshness Indicating Properties of Hibiscus rosa‐sinensis Extract‐Enriched Partially Deacetylated Chitin Nanofibrils/κ‐Carrageenan Films

The escalating environmental concerns over petroleum‐derived plastics are driving demand for renewable, biodegradable alternatives that offer active functionalities beyond passive containment. Active packaging that combines antioxidant protection with visual freshness indication is particularly promising, as they can simultaneously extend food shelf‐life while enabling real‐time quality monitoring. In this study, bionanocomposite films were fabricated via facile solution casting, combining partially deacetylated chitin nanofibrils (Ch) and κ‐carrageenan (κC) as the biopolymeric matrix, enriched with 0%, 2%, 4% and 8% Hibiscus rosa‐sinensis extract (HBE), an anthocyanin‐rich, natural bioactive and pH‐responsive colourant. The effect of HBE concentration on the physicochemical (structural, thermal, mechanical, barrier, optical) and antioxidant properties was systematically investigated. Preliminary practical applicability of the films was demonstrated through colorimetric response during raw cow‐meat storage, and shelf‐life extension of bell peppers under ambient storage conditions. HBE incorporation significantly ( p < 0.05) enhanced films flexibility, water vapour and oxygen permeability, opacity, UV/light barrier, water resistance and antioxidant activity in a concentration‐dependent manner, albeit at the expense of tensile strength and thermal stability. The Ch/κC/HBE 8 formulation exhibited the strongest antioxidant performance, with DPPH‐radical‐scavenging activity of up to 69%, total phenolic content (TPC) of up to 4.7 ± 0.10 mg GAE/g and ferric reducing antioxidant power (FRAP) of up to 3.58 ± 0.12 mg GAE/g. During meat application trial, Ch/κC/HBE 8 produced pronounced visible colour changes, indicating potential for freshness monitoring. Moreover, in a preliminary ambient‐condition storage trial, bell peppers wrapped in Ch/κC/HBE 8 retained their fresh appearance and showed lower weight loss and higher firmness than unpacked controls over 14 days. Overall, these findings demonstrate that HBE‐enriched Ch/κC films show promise as antioxidant, pH‐responsive indicator films food‐packaging materials with preliminary freshness‐indicating functionality and produce shelf‐life extension.