Assessment of Nutritional and Physicochemical Characteristics of Unmodified and Chemically Modified Water Yam(Dioscorea alata) Starches

Abstract Starch is a polymeric carbohydrate which is made up of several glucose units connected by glycosidic linkages. It can be sourced from plant tubers and grains. With the increase of new food and non-food industries, more starch is needed as a raw material and there is the need to look for alternative sources of commercial starch. In this study, starch was extracted from water yams (Dioscorea alata), which is considered as lesser yam and thereafter, modified chemically via acetylation, oxidation, and a combination of acetylation and oxidation processes. Using established techniques, the physicochemical characteristics and nutritional makeup of the unmodified and chemically modified water yam starches were assessed, and the outcomes were compared. Assessment using a Fourier Transform Infrared spectrophotometer (FTIR) was carried out to ascertain how the functional properties of both unmodified and modified starch had changed. The moisture content of modified starches was higher, while the ash, fat, and protein contents were lower in comparison with the unmodified. Compared to other starch samples, acetylated/oxidized starch exhibited a higher swelling power, a better ability to absorb water and oil, and a higher content of crude fiber. Compared to unmodified starch, oxidized starch was more soluble. When comparing unmodified starch to modified starch, FTIR analysis showed differences in the absorption bands of the former at 3389 cm− 1 (O-H), 2932 cm− 1 (C-H), and primary, secondary, and tertiary amide moiety at 1079, 1643, and 1205 cm− 1, respectively. The physicochemical and nutritional properties of the starch were generally affected by modification making them a potential excellent material for industrial applications.