Morphological and structural studies of thermally treated starch-fatty acid systems

A series of starch-fatty acid samples were prepared using three types of starches differing in their amylose content i.e. maize, pea and amylomaize and three fatty acids differing in their chain length; i.e. myristic, palmitic and stearic. Two different modes of heating the starch systems were employed; i.e. either prior to the addition of the acid to starch aqueous dispersions or after heating the dispersions at the predetermined temperatures 75, 85 or 98 °C. Light and SEM microscopic examination indicated that amylose-fatty acid interactions taken place during starch gelatinization retarded the destruction of the granules depending on the heating temperature. XRD studies revealed that the degree of crystallinity exhibited by the starch samples was dependent on the amylose content, the fatty acid chain length and the modes of heating employed.

► Starch-fatty acid systems heated from 75 to 98 °C, differed in their morphological and structural characteristics.
► These characteristics were dependent on the amylose content, the fatty acid length and the mode of the thermal treatment.
► The presence of fatty acid molecules retarded fairly effectively the gelatinization process to all types of starch examined.
► The degree of crystallinity exhibited by the samples was proportional to the temperature of heating the samples.