Extraction and Characterization of Starch from Sweet Potato (Ipomea batatas) Peels

Abstract

Sweet potato peels are abundant by-products of sweet potato processing and their utilization has gained interest due to their high starch content. This research is focused on the extraction and characterization of starch from sweet potato peels using sodium acetate buffer solution as extraction medium. The percent yield and moisture contents were determined to be 70.0 % and 9.5 % respectively. The extracted starch was characterized via X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The TGA curve gave three degradation stages with the initial stage which starts instantly when there is temperature rise and ends at about 300 °C retaining about 95.8 % of the total material. The second stage is the main degradation stage which ends at around 470 °C with only about 5.40 % of material left. The last step ends with the formation of carbon black between 470 - 600 °C. The XRD profile of the starch exhibited weak peaks at 2θ = 12.0 °, 15.0 °, 17.0 ° and 22.2 ° characteristic of amorphous B-type starch. The starch granules observed by SEM showed a densely packed material with notable porous surface. The properties of the studied starch showed promising potential as a material from which products such as drugs carriers, adsorbates and ion resin exchangers can be made.