Deep Coloration of Wool Fibers Using Oxides of Reducing Sugars

Abstract

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.

In the fields of food chemistry, it was well known that oson compounds, such as glucoson and glycoson, are one of important intermediates of the Maillard reaction. However, these oson compounds are usually produced via the slow air oxidation of the reducing sugars. In this paper, shortening of the coloration time of the wool fibers was investigated by use of a mixture of the sugar oxides including the oson compounds, where the sugar oxides could be easily produced by their chemical oxidation using Fenton reaction. Predictably, the reactions of the wool fibers with sugar oxides could afford both their quick and deep coloration; they became dark brown within only 2 hours in the present of glucose oxides.