Formulation and Quality Evaluation of Goat Milk Cosmetic Soap Using Different Vegetable Oil Compositions

Abstract

This study endeavors to produce and scrutinize goat milk bar soap, given that it assimilates depleted cooking oil that constitutes refined effluent oil, in relation to the standard demands for bar soap (SNI 3532:2021) plus pristine milk criteria (SNI 3141.1-2011), while accentuating ecological matters. Domestic palm and coconut waste oils constitute the chief components, purified through a basic mechanical operation. These components merge using olive oil, goat milk, and NaOH. For production of the soap, temperatures under 50 °C were employed, via the cold process method, followed by curing for 30 days. Subsequent to curing, the soap was assessed in terms of pH, hardness, as well as antibacterial resistance. The pH existed in a span from 9 to 10, with hardness assessed at 2.5–4 kg/cm². Antibacterial tests suppressed Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, exhibiting zones from 0.05 to 1.2 mm, which remain inside the SNI quality limits. These discoveries reveal that utilizing domestic refuse cooking oil to fabricate goat milk bar soap presents an environmentally sound option for waste disposal. Kitchen refuse is thus converted to practical everyday commodities like bath soap.