Transesterification, GC-MS profiling, and in vitro antimicrobial potential of oil obtained from seeds of Citrus maxima (Burm.) Merr

Oil-producing crop plants are vital not only for biodiesel production but also for their pharmacological benefits. In this research, the prime focus was on identifying oils and evaluating antimicrobial activity obtained from seeds of Citrus maxima (Burm.) Merr. for forestry biorefinery and bio-based product development. Extraction with n-Hexane solvent gave a 36.04% oil yield from the seeds. Method optimization studies were also carried out to get the highest yield of transesterified biodiesel by adjusting the alcohol/solvent, catalyst type concentration, temperature, and time. The physicochemical properties include density, specific gravity, kinematic viscosity, refractive index, acid value, and saponification value. Other than the above the cloud point, pour point, and flash point of the crude and transesterified oil were performed as per the ASTM standard procedures. Gas Chromatography-Mass Spectroscopy (GC-MS) analysis was performed to identify phytoconstituents. The in vitro antimicrobial studies of seed oil (CM-SO) and transesterified oil (CM-FAME) were conducted with bacterial and fungal strains. Morphological changes were evaluated by field emission scanning electron microscopy (FESEM). As determined by GC-MS, 36 constituents were identified, and the total fatty acid was observed to be 95.16% which includes saturated fat (66.72%), monounsaturated fatty acid (27.84%) in seed oil was higher than the polyunsaturated fatty acid (0.60%) present, along with trans-fatty acid (22.58%). Among the total phytoconstituents, hexadecanoic acid methyl esters content (32.85%) was found to be the highest following 9-Octadecenoic acid, methyl ester, (Z)- (21.82%). According to the antimicrobial assay, CM-SO and CM-FAME both showed significant activities against the selected microorganisms. The present investigation suggested using Citrus maxima seed oil not only in crop and forestry biorefinery but also in pharmaceutical industries.