Abstract
AbstractThe effect of some physical and chemical treatments on the functional and pasting characteristics of native tigernut starch (TNNS), native sweet potato starch (SPNS) and blends of tigernut-sweet potato starch were studied. Native tigernut and sweet potato starches were subjected to physical (annealing and heat-moisture) and chemical (acetylation) modifications and compared to tigernut (T)-sweet potato (S) starches blends (T75:S25, T50:S50, T25:S75). Only heat-moisture treatment (THMT) significantly (p ≤ 0.05) increased water absorption capacity of the TNNS while only acetylation significantly (p ≤ 0.05) increased the oil absorption capacity of the native tigernut starch. The bulk density was significantly (p ≤ 0.05) reduced by annealing and acetylation. In addition, TNAS, mixture of blends and SPNS had higher swelling capacity than TNNS. The final and peak viscosities of TNNS, SPNS and all the starch blends were between (217–280 RVU) and (214–395.3 RVU) respectively with SPNS having the highest va...
Highlights
Starch is a glucose polymer comprising amylose and amylopectin macromolecules (Obanni & Bemiller, 1997)
Material Sweet potatoes and tigernut tubers were purchased from the local Oba market in Akure, Ondo State, Nigeria
Extraction of starches Tigernut and sweet potato native starches were extracted by the modified method of Umerie, Obi, and Okafor (1997)
Summary
Starch is a glucose polymer comprising amylose and amylopectin macromolecules (Obanni & Bemiller, 1997). It is widely available in nature and produced in all green plants. It has been extracted from several raw sources including tubers, cereals and legumes and utilized to influence food characteristics such as aesthetics, moisture, consistency, and shelf life (Adebowale, Sanni, & Fadahunsi, 2011). When native starch granule is heated in the presence of water, it gelatinizes but later retrogrades during storage. This behaviour, in addition to its low shear stress resistance and thermal decomposition, high retrogradation and syneresis, makes native starches to have limited industrial application. Modification (chemical, physical and enzymatic) treatments and mixture of blends of starches of different sources have evolved to reduce, if not totally remove the negative attributes of native starches (Adebowale et al, 2011; Awolu & Olofinlae, 2016; Ortega-Ojeda & Eliasson, 2001)
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