A particulate glucomannan gel is produced by dissolving glucomannan-rich flour in water, precipitating glucomannan from the solution with ethanol, treating the precipitated glucomannan with an alkali to transform to water-insoluble, irreversible hydrogel particles, recovering and drying the hydrogel particles, and milling dried particles to a desired particle size. The resulting gel particles are incorporated into hygienic or cosmetic preparations as a deposit-cleaning agent.