<![CDATA[Background: The use of natural ingredients in hair care products can provide an alternative approach to developing more environmentally friendly formulations. Quinoa (Chenopodium quinoa Willd.) extract contains compounds with potential as a natural biosurfactant. Objective: This study aimed to evaluate the biosurfactant activity of quinoa extract and determine the shampoo formula with optimal physical characteristics and stability. Methods: Quinoa extract was obtained by maceration and evaluated for biosurfactant activity based on surface tension and emulsification index (E24). Three shampoo formulas containing different concentrations of quinoa extract were prepared and evaluated for pH, viscosity, foam volume, homogeneity, and organoleptic properties during storage using the cycling test method.Results: Quinoa extract reduced the surface tension of water from 72 mN/m to 37.77 mN/m and showed an emulsification index of 36.66%. All shampoo formulas exhibited stable physical characteristics during the testing period and met the requirements of the Indonesian National Standard (SNI). Formula 2, containing 10% (w/v) quinoa extract and 3.75% (w/v) Cocamide MEA, demonstrated the most optimal overall physical characteristics and stability.Conclusion: Quinoa extract has potential as a natural biosurfactant in shampoo formulations. Formula 2 demonstrated optimal physical characteristics and stability during storage and may be further developed as a natural ingredient-based shampoo.]]>
