Some Properties of Sotetsu (Cycas revoluta Thunb.) Trunk Starch

Some chemical and physical properties of starch prepared from trunks of sotetsu (Cycas revoluta Thunb.) (sotetsu A) were compared with starches prepared from seeds of sotetsu (Sotetsu B) and ginkgo (Ginkgo biloba L.) seeds. The results obtained were as follows 1) The mean particle size of sotetsu A, sotetsu B and ginkgo starches were 13.2pm, 9.5 pm and 12.4 pm, respectively. 2) The susceptibility of sotetsu A starch granules to hog pancreatin was similar to that of sweet potato starch granules having relatively high susceptibility. By scanning electron microscopy (SEM), the appearance on the surface of sotetsu A starch granules attacked by pancreatin was quite similar to the case of normal maize starch granules, for which the enzymatic attack usually started with small pits on the surface of the granules and then the pits increased in number and in size during the subsequent enzyme attack. 3) The initiation temperature for gelatinization of sotetsu A starch, by photopastegraphy and differential scanning calorimetry (DSC) were 58.5 and 63. it, respectively. The enthalpy change, 4H, determined by DSC was 3.7 cal/g, which was relatively lower than that of the other two starches. The maximum viscosity and breakdown of sotetsu A, determined by Brabender's amylography (6%), were 460 BU and 30 BU, respectively. Breakdown was low like sotetsu B and ginkgo starches. 4) The amylose contents of sotetsu A starch, determined by amperometric titration and enzyme-chromatographic method, were 25.2, 23.2%, respectively. 5) Texture of 6% starch gels was determined by curdmeter and a Rheoner; sotetsu A formed gel having low hardness and breaking force and relatively high cohesiveness.