Abstract

Starfruit extract is used as a base for making natural soap that is more environmentally friendly and beneficial for health. The aim of this study is to identify the optimal conditions for adding starfruit extract to natural soap production, which involves citric acid and surfactant components. The method involves maceration and extraction of starfruit to obtain citric acid by immersing it in 80% ethanol. The soap is produced using a hot process at temperatures between 70-80 °C with three formulas: F1 (200:200:10), F2 (225:175:15), and F3 (250:150:20), representing different ratios of virgin coconut oil (VCO), olive oil, and starfruit extract, respectively. Potassium hydroxide (KOH) is used as an alkali at a concentration of 30%. After the soap is made, MES (Methyl Ester Sulfonate) (a plant-based surfactant), sodium citrate (Na3C6H5O7) as a preservative, and sodium bicarbonate (NaHCO3) as a cleanser are added. Testing of the three soap formulas showed they all meet Indonesian National Standards (SNI). Among 20 respondents, F1 was rated the highest in terms of color, scent, and softness. It had 83% foam stability, 0.85% moisture content, a pH of 8, and 0.001% free alkali content. These results suggest that consumer preference is influenced by the starfruit extract content.