Conditional sustainability in lignocellulosic packaging systems through a multi-gate barrier design framework

Lignocellulosic materials have emerged as promising alternatives to petroleum-based packaging due to their renewability, biodegradability, and dry-state oxygen barrier properties. However, barrier performance in these systems is highly dependent on conditions. Elevated humidity, mechanical fatigue, variability in industrial processing, and end-of-life constraints frequently compromise functionality and sustainability, revealing limitations of approaches that evaluate barrier metrics in isolation. This review proposes a Multi-Gate Framework to conceptualize lignocellulosic packaging performance as an integrated and condition-dependent system. The framework organizes determinants into five interdependent Gates: (1) the Molecular Gate, governing functional group chemistry, hydrogen bonding density, and free volume regulation; (2) the Microstructural Gate, defining porosity, tortuosity, and phase continuity; (3) the Environmental Gate, addressing humidity plasticization, temperature effects, mechanical damage, and photo-oxidative aging; (4) the Processing and Scalability Gate, integrating rheology, drying efficiency, and industrial reproducibility; and (5) the Circularity and Sustainability Gate, validating recyclability, compost ability standards, and life-cycle impacts. Rather than treating sustainability as a central material attribute, the multi-gate model positions it as a conditional outcome emerging from coordinated optimization across molecular design, structural organization, environmental stability, scalable manufacturing, and circular compatibility. This systems-level roadmap provides a structured pathway to translate laboratory-scale lignocellulosic barriers into commercially viable, environmentally validated packaging solutions.