eng Enviro Research Publishers Current Research in Nutrition and Food Science Journal 2347-467X 2322-0007 2026-07-01 14 2 26486 article Urmila Gupta Phutela 2 Yashika Aggarwal 1 Harmandeep Kaur 1 Department of Microbiology, Punjab Agricultural University, Ludhiana, India Department of Renewable Energy Engineering, Punjab Agricultural University, Ludhiana, India Horticultural crops post-harvest processing waste offers a sustainable pathway for developing low-cost biocatalysts that can improve the bioconversion efficiency of agricultural residues. This study investigated the production and application of Citrus limetta and Citrus × sinensis peel derived bioenzyme in 5-L PET containers as a biological pretreatment for enhancing the biodegradability of Oryza sativa straw for biogas production. Bioenzymes were prepared by fermentation of peels and analysed for physicochemical and enzymatic attributes, and were found to be acidic in nature and possessing high lignocellulolytic activity, with Citrus limetta peel bioenzyme being more potent in terms of enzymatic activities, including 679.63 U/mL amylase enzyme activity, endoglucanase activity of 1121.10 U/mL, β-glucosidase activity of 2223.76 U/mL, exoglucanase activity of 169.69 U/mL, and laccase activity of 0.91 U/mL, compared to the relatively lower activities of Citrus × sinensis peel bioenzyme. Bioenzymes thus optimized and analyzed were used for application at various concentrations (1-10%) for Oryza sativa straw pretreatment before anaerobic digestion and induced significant modifications in the chemical and proximate composition of straw, improving substrate accessibility during anaerobic digestion. Biogas production increased in a concentration-dependent manner for both bioenzymes. The highest cumulative biogas yield was obtained with 10% Citrus limetta peel bioenzyme pre-treatment, achieving 980.6 L/kg VS which is about 1.16-fold higher than the corresponding Citrus × sinensis treatment and 5-fold higher than the untreated straw. Overall, citrus peel bioenzymes derived formulations, will offer a sustainable and effective biological pretreatment strategy for improving the anaerobic digestion of agro-industrial wastes. https://www.foodandnutritionjournal.org/volume14number2/comparative-conversion-of-citrus-peel-waste-citrus-limetta-and-citrus-x-sinensis-into-functional-bioenzymes-for-pre-treatment-of-oryza-sativa-straw-to-enhance-biogas-yield/ Biogas Bioenzyme Citrus limetta Citrus × sinensis Oryza sativa straw Pretreatment