Modification of maize starch by thermal processing in glacial acetic acid

Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods were used to determine if corn starch¯glacial acetic acid mixtures can be melted and thermally processed at reasonable temperatures. DSC studies showed that the melting temperature of dry starch was reduced from about 280 to 180°C in the presence of >30% acetic acid. Glass transition temperatures varied from 110 to 40°C at 15 and 45% acetic acid, respectively. XRD showed the loss of native starch crystallinity and the formation of V-type complexes. Addition of 10% water decreased the melting temperatures to 140¯150°C while addition of a base (sodium acetate) had little effect. Some possible applications of processing starch in glacial acetic acid will be discussed.