Nanocellulose from passion fruit peel for starch-xanthan gum films and cherry tomato coatings

Postharvest losses of fruits and vegetables are a key challenge for food sustainability, creating a demand for biodegradable films and coatings to prolong shelf life. Passion fruit peel (PFP), an abundant agricultural by-product contains significant amount of cellulose and holds great potential as a raw material for value-added applications. This study focuses on the valorization of PFP through the extraction of cellulose using microwave-assisted alkali treatment, followed by bleaching and acid hydrolysis to obtain nanocellulose for film preparation. The optimized extraction conditions were microwave power of 561.86 W, irradiation time of 4.33 min and NaOH concentration of 7.61% achieved 71.55% delignification yield. Nanocellulose was obtained via sulfuric acid (35%) hydrolysis, yielding 23.20 ± 3.03% with a whiteness index of 31.561 ± 0.912%. Fourier transform infrared (FTIR) analysis confirmed successful cellulose isolation, while crystallinity increased from 59.48% (cellulose) to 68.51% (nanocellulose). Further, nanocellulose (5-20% w/w) was incorporated into starch-xanthan gum-based film. The film containing 15% nanocellulose (NC3) showed a tensile strength of 2.858 ± 0.145 MPa, solubility of 34.81 ± 3.42% and water vapour permeability (WVP) of 6.473 × 10^-6 g/Pa-m-h. This film was further applied as a coating on cherry tomatoes and its effect was studied. Coated tomatoes showed significantly lower weight loss, higher firmness and minimal changes in total soluble solids while maintaining stable pH compared to uncoated samples indicating reduced respiration and moisture loss, delayed senescence and microbial growth. Overall, this study demonstrates the potential of converting PFP waste into value-added nanocellulose-based films and coatings, thus offering a sustainable alternative to reduce postharvest losses.