What is "colour retention agent"

n. any compound added to a food product in order to retain or enhance its colour during storage or cooking

Colour retention agents are food additives that are added to food to prevent the colour from changing. Many of them work by absorbing or binding to oxygen before it can damage food ( antioxidants). For example, ascorbic acid ( vitamin C) is often added to brightly coloured fruits such as peaches during canning.