MICRO-TECHNIQUE FOR THE IDENTIFICATION OF FOOD HYDROCOLLOIDS

A simple technique is described for the identification of 13 hydrocolloid powders including pectin, seed gums, gum exudates, seaweed extracts, gelatin and pre-gelled starch. The method is based on the microscopical appearance of the different hydrocolloid particles when treated with aqueous Toluidine Blue under neutral and acid conditions. The reaction with iodine solution provided a confirmatory test for eight of the hydrocolloids. The technique relies on the combined physical and chemical properties of the individual hydrocolloids and gives results that are easy to interpret even for workers with limited experience of optical microscopy.