Integrated biovalorization of Pongamia pinnata seeds for sustainable biodiesel and bioethanol production

Abstract Biofuels represent a sustainable alternative to fossil fuels, with non-food feedstock offering particular promise. This study evaluated Pongamia pinnata seeds as a dual feedstock for biodiesel and bioethanol production. Moisture content was determined at 8.0%, favorably lower than most lignocellulosic biomasses. FTIR analysis confirmed the presence of cellulose, hemicellulose, and lignin, indicating its suitability for biofuel production. Biodiesel was produced via alkaline transesterification, with the highest conversion (70%) obtained at a 5:1 alcohol-to-oil ratio. The de-oiled seed cake, rich in carbohydrates and low in lignin, was optimized for glucose release through Response Surface Methodology. Optimal conditions (100°C, 2.5 g substrate, 1.75% H 2 SO 4 , 60 min) yielded 429 mg g −1 glucose. Enzymatic hydrolysis further enhanced sugar release, with maximum glucose (118.21 mg g −1 ) achieved at 72 h with a 2.0 mL enzyme load. Subsequent fermentation with Saccharomyces cerevisiae produced 6.71% ethanol. These findings highlight the potential of P. pinnata as a feedstock for integrated biorefineries, supporting sustainable biofuel production.