Abstract
Starch obtained from matured potato was air classified into small granule fraction (<10pm) and large granule fraction (>μm). The structural, rheological and chemical properties were studied in order to elucidate the difference of the fractionated starches. There was no difference in the gelatinization temperature determined by amylography and photopastegraphy between small fraction and large fraction. The small starch fraction showed a typical two step swelling pattern by amylography. There was also no difference in iodine binding capacity, β-amylolysis limit, chain length distribution, amylose content, structure of Nageli amylodextrin between two starch samples. Regarding to digestibility of the starch fractions bysulfuric acid and enzymes, small granule starch was attacked much faster than larger one at the stage of the initial reaction. These seemed to be attributed to the larger surface area of small granule starch compared with the larger one. The main difference observed in the small and large starch granule was the content of phos phorus. The phosphorus content of small granule fraction was as high as 140% compared with the larger one. This seemed to be the main reason in the difference of the shape of amylogram and solubility curve of the starch samples. Here, we would like to conclude that there was no essential difference in starch structure between large- and small-granule starch obtained from matured potato, except rather big difference in phosphorus content which seemed to affect greatly some rheological properties.
