Physicochemical Comparison of Soaps Produced from Fresh, Cooked, and Naturally Treated Oils

Background and Objectives: Green chemistry plays a vital role in the pharmaceutical industry. Utilizing herbs to reduce rancidity and oxidation in various cooked oils is a cost-effective and environmentally friendly approach. Cooked oil significantly impacts environmental pollution, affecting aquatic life and soil quality. This research aims to create high-quality soap using herb-infused oils to treat waste oils exhausted from restaurants, offering a practical solution to sustainable waste management. In addition, it provides various skin benefits, such as moisturizing, and cleaning. Method: A simple small-scale cold process method was used to formulate three types of soaps with different oils within. One formulation uses cooking oil from a fast food restaurant; named as soap (W), another uses fresh oil; named as Soap (F), and the third Soap (T) uses greenly treated oils with turmeric powder, peppermint, and rosemary powder in a certain concentration. Different physicochemical tests assessed the physicochemical quality of soap through various tests, including organoleptic evaluation, hardness, pH measurement, moisture content, matter insoluble in alcohol, foam stability, cleaning ability, free fatty acid or alkali content, and total fatty matter. The economic feasibility was evaluated by analyzing production costs and environmental impact, emphasizing the benefits of using waste oils for sustainable and cost-effective soap production. Results: Soap (T) exhibited a refined yellow color, smooth texture, and met ASTM and ISO standards across all parameters. Notably, Soap (T) showed the longest foam stability (9 minutes, Kd=0.077) and the lowest free fatty acid content (0.751%), indicating superior quality and skin safety. Soap (W) and Soap (F) also met the standards but with lower performance metrics. Soap (T) is identified as the optimal formulation, balancing quality, sustainability, and practical performance. Conclusion: Soap (T) met all ASTM and ISO standards, showing superior quality and performance. Its green, eco-friendly components help balance skin moisture, Soap (T) stands out as the best option for practical use and sustainability. Further studies on reducing wrinkles, and preventing acne are recommended.