Polycaprolactone/cutin blends for the improvement of moisture barrier and grease resistance of paper for food use

The increasing demand for sustainable food packaging has driven interest in biodegradable coatings to enhance the functional properties of paper-based materials, whose poor moisture barrier and grease resistance limit direct application in food packaging. This study investigates the potential of polycaprolactone (PCL)/cutin blend-based coatings at improving the functional properties of paper intended for food packaging applications. Two different PCL:cutin ratios (1:0.6 and 1:1) were applied on paper, with and without glycerol, as single and double-layer using the bar coating technique. The coated samples were evaluated for water vapor transmission rate (WVTR), grease resistance, contact angle, mechanical strength and seal strength. The findings indicate that the coatings significantly enhanced the moisture barrier, achieving a reduction of about 90 % of the WVTR with a double-layer coating made with PCL:cutin ratio of 1:0.6 (405 ± 12 g·day⁻¹·m⁻²), compared to uncoated paper (4348 ± 69 g·day⁻¹·m⁻²). Grease resistance tests confirmed that all coated samples exhibited maximum oil repellency, maintaining effectiveness even after mechanical folding. These results highlight the functionality of cutin, a naturally derived biopolymer, in enhancing PCL-based coatings as an effective and eco-friendly alternative for food packaging. The optimal formulation (PCL:cutin 1:0.6, double-layer coating) ensures moisture and grease resistance, good mechanical properties , making it a promising sustainable solution for the packaging industry. • PCL/cutin coatings reduced WVTR by 90 %, enhancing moisture resistance and improving barrier properties of paper. • Coated samples achieved maximum grease resistance, maintaining oil repellency even after mechanical folding. • Double-layer coatings demonstrated to be heat saleable, making the coated paper suitable for hermetic packaging. • PCL/cutin blends provide a biodegradable and eco-friendly coating for compostable packaging. • The use of cutin obtained from tomato by-products is an example of agricultural side stream valorization or upcycling, according to principles of circular economy.