European Young Cereal Scientists and Technologists Workshop edition:13 location:Freising, Germany date:May 14-16
Starches of enhanced cold-water swelling capacity can be used in instant and convenience foods like puddings, pie fillings, gravies, soups and sauces. Since traditionally produced pre-gelatinized starches have poor properties due to loss of granular integrity, efforts have been made to develop granular cold-water swelling starches. This can generally be achieved by heating starch in the presence of aqueous alcohol, during which the native double helical order is transformed into single helical order. Presumably, this happens by complex formation between both amylose and amylopectin with the alcohol. Amylose is essential for retaining granular integrity. Removal of the residual alcohol from the single helix cavity is alleged to render cold-water swelling starch.
This study aimed at further understanding the conversion of native into granular cold-water swelling starch. First, a laboratory scale aqueous ethanol procedure was successfully used to gradually convert native maize starch to granular cold-water swelling starch by varying ethanol concentration and treatment temperature. Swelling power increased concomitant with starches showing an increased level of VH-type crystallinity. A waxy maize starch was included as well to study the role of amylopectin in the formation of V-type crystals. Removal of alcohol by high temperature drying resulted in a VA-type X-ray diffraction pattern. However, this transition was reversible and it was shown that high temperature drying is not necessary to confer upon starch its cold-water swelling characteristics. Finally, beyond-state-of-the-art time-temperature resolved X-ray measurements during the conversion of native to cold-water swelling starch provided insights in the structural transitions taking place.