Title: Antimicrobial Performance of Cold-Process Soap Formulated from Neem Seed Oil and Palm Kernel Oil Blends
Authors: TIMOTHY OJOAROME YAHAYA, JIMESHIO JOSEPH GBERINDYER.
Volume: 10
Issue: 9
Pages: 188-193
Publication Date: 2026/09/28
Abstract:
: This study evaluated the antimicrobial performance of bar soaps produced by cold-process saponification of neem seed oil (Azadirachta indica) and palm kernel oil. Five formulations were prepared: 100% neem oil (S1), 100% palm kernel oil (S2), 50:50 neem/palm kernel oil (S3), 70:30 neem/palm kernel oil (S4), and 30:70 neem/palm kernel oil (S5), with a commercial Tura soap as control. Antibacterial activity was assessed by agar-well diffusion against Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa at 100, 50, 25 and 12.5 mg/mL. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were evaluated by broth dilution and subculture. The study showed formulation- and organism-dependent activity. S2 produced the largest experimental inhibition zone against S. aureus at 100 mg/mL (22 mm), whereas S5 produced the largest zones against B. subtilis (26 mm) and P. aeruginosa (17 mm). The commercial control remained more active against S. aureus and generally had lower MIC/MBC values, although S2 and S5 compared favorably with it against B. subtilis. The findings support further development of locally sourced vegetable-oil soaps, but they also show that an in-vitro antimicrobial effect should not automatically be equated with regulated antiseptic performance or clinical efficacy.