Waste Valorization of Passion Fruit Peel Hydrolysate for Bacterial Cellulose Production: Influence of Nitrogen Source on Yield and Functional Properties for Food Packaging

The valorization of agro-industrial residues represents a strategic approach to advancing sustainability and circular bioeconomy principles in the food sector. Although bacterial cellulose (BC) production from waste substrates has been widely explored, limited attention has been given to the role of nitrogen source modulation in complex fermentation systems. This study evaluated passion fruit peel hydrolysate (PFPH), a cellulose- and hemicellulose-rich by-product, as an alternative carbon source for BC production using a symbiotic culture of bacteria and yeast (SCOBY) under static conditions. Acid hydrolysis and detoxification were performed to obtain fermentable sugars while minimizing inhibitory compounds. Different nitrogen sources and purification strategies were comparatively assessed. The highest purified BC yield (81 g L^-1 of culture medium) was obtained using ammonium sulfate, whereas sodium nitrate promoted greater impurity removal (77.51% mass reduction). Structural and chemical analyses (FTIR, XPS, and XRD) confirmed effective delignification, enhanced surface purity, and increased crystallinity. SEM revealed a homogeneous nanofibrillar network, and thermogravimetric analysis indicated thermal stability up to approximately 300 °C. Soil burial assays showed 26% mass loss after 42 days, demonstrating controlled biodegradation consistent with food packaging requirements. Overall, PFPH proved to be an efficient and sustainable substrate for BC biosynthesis. The modulation of nitrogen source significantly influenced both production yield and structural properties, highlighting the potential of this system for developing environmentally responsible biopolymer materials for food packaging applications.