Color Change in and Soil Removal from Cocoa Soiled Cloth in Hard Water

IEC 60456 declared the cocoa soiled cloth to be one of the standard soiled test cloths for measuring the performance of the clothes washing machines. Researchers for textile washing have known that cocoa soiled cloth has shown unpredictable washing performance. The color of cocoa mainly comes from flavonoids, and flavonoids reversibly change color with alkalinity from pH 1 to pH 7 as food colorants. The color change of flavonoids under various washing conditions, in the alkali solution, has not yet been confirmed. In this study, we have investigated the color change and the soil removal of the cocoa soiled cloth which were washed with alkaline washing liquids of various hardnesses. The cocoa soiled cloth which was washed in the water which was 60ppm or higher became darker than the soiled cloth. When the cloth was washed in the detergent solution, the cloth was slightly darker only when the washing condition was $20^{\circ}$ and 250ppm. As the water hardness increased, the soil removal decreased and the higher washing temperature was more effective.