Comprehensive characterization of biodegradable edible films activated with rose and marigold extracts and application of active edible coatings to extend the postharvest storage life of guava.

This study investigated the physical, mechanical, optical, thermal, and biochemical characters of carboxy methyl cellulose (CMC) and gum arabic (GA) based active edible films activated with rose leaf (RL) and marigold petal (MP) extracts, their impact on the shelf life and postharvest quality of guava fruits when stored under cold condition (10 ± 1 °C). Physical, mechanical and optical characteristics were enhanced by the incorporation of plant extracts. Water solubility of films decreased upon addition of plant extracts, with MP extract films showing the lowest solubility. Water vapor transmission rate (WVTR) lowered when plant extracts were added, lowest for RL extract incorporation (50.35, 8.78 g/m/day) when compared to pure forms (66.58, 15.97 g/m/day) for CMC and GA, respectively. Thermogravimetric analysis results revealed increased residue content in CMC + MP films and lower residue in CMC + RL films above 300 °C. FTIR analysis demonstrated interactions between CMC hydroxyl groups and plant extract components, with broad OH and CH stretching peaks. When applied to guava fruits, the shelf life was extended up to 18 days for GA + RL, CMC + MP, and CMC + RL coatings. CMC + RL coated fruits retained higher weight retention percentage (91.03 %) and showed lower ethylene production rates along with enhanced biochemical properties. Antioxidant activity (DPPH) was better preserved in coated fruits, with CMC + RL being the most effective. PME and APX enzyme activities were lower in active-coated fruits. CMC + RL coatings outperformed all other coating formulations in maximizing storage life (18 days) and maintaining quality attributes with lowest ripening index (35.93) and total colour difference (82.80).