Deep Coloration of Wool Fibers Using Oxides of Reducing Sugars

It was well experienced in our daily living that foods including both reducing sugar, such as glucose,and amino compound, such as amino acid and protein, become yellow or brown after the heating process or long storage such as the fermentation process. These coloration reactions are called the Maillard reaction,melanoidin reaction, or browning reaction. The natural coloration of foods such as beer, soy sauce, and miso are well-known examples of the melanoidin colorants caused by the Maillard reaction. In our previous works, it was clarified that protein fibers such as wool, silk, and leather were colored yellow or brown by reactions with reducing sugars. However, it was clear that their coloration speed was very slow compared with usual synthetic dyes. For example, brown coloration of the wool fibers was required 24 hours or over, where xylose was used as one of reactive reducing sugars.