Background and objectives: The commonly used afrosimetric foam-height method for quantifying saponins in quinoa is rapid but imprecise. A rapid UV/Vis method, utilizing the Liebermann-Burchard (LB) color reaction, was compared to the foam method across a range of saponin levels in washed and unwashed seed. Findings: A 6 min UV/Vis method provided greater precision and accuracy than the afrosimetric method at the lower saponin levels found in washed quinoa. The afrosimetric method did not differentiate saponin levels below 0.6 mg/mL but allows for useful relative comparisons of saponin content in unwashed quinoa where the foam height is large. Conclusions: The UV/Vis method is superior for analyzing saponins present on washed quinoa seed, while the foam method is adequate for saponin measurements in unwashed seed. Significance and novelty: The UV/Vis assay provides a new tool that can be used for in-process quality control in large-scale processing facilities, allowing for rapid, accurate determination of completion of the desaponization step.