Browsing by Author "Amonsou, Eric"
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Item Effect of high-pressure homogenization on the structural, thermal and rheological properties of bambara starch complexed with different fatty acids(Royal Society of Chemistry, 2016-08-17) Oyeyinka, Samson; Singh, Suren; Ying, Ma; Amonsou, EricThe effect of high-pressure homogenization (HPH) on the degree of complexation of different fatty acids with bambara starch was studied. HPH significantly increased the complexation of bambara starch with palmitic, stearic, oleic and linoleic acids. However, saturated fatty acids generally showed higher complexing ability than unsaturated ones. For all fatty acids, bambara starch showed a higher complex index than corn and potato starches, which could be associated with the variation in amylose contents (22.5–31.5%). The formation of V-amylose crystalline materials was confirmed by XRD with peaks at 2q ¼ 7.4, 12.9 and 19.9. Bambara starch–fatty acid complexes displayed significantly higher melting temperatures (95.74–103.82 C) compared to native uncomplexed starch (77.32 C). Homogenized bambara starch complexes were non-gelling while unhomogenized complexes produced weak gels, with G0 > G00 in the range of 0.1–10 Hz. Complexation of bambara starch with fatty acids using HPH may be employed in the production of modified starch with non-gelling properties and higher thermal stability suitable for certain industrial applications.Item Effect of lipid types on complexation and some physicochemical properties of bambara groundnut starch(Wiley, 2016-06-04) Oyeyinka, Samson; Singh, Suren; Venter, Sonja; Amonsou, EricThis study investigated the effect of stearic acid, linoleic acid, and lysophosphatidylcholine on complex formation and physicochemical properties of bambara starch in comparison with potato starch. The complexation index reached maximum at 2% lipid concentration. Bambara starch complexed better with stearic acid than with linoleic acid and lysophosphatidylcholine. A similar trend was observed for potato starch but to a lesser extent. All lipids significantly reduced the peak and setback viscosities of bambara starch, but increased the final viscosity. Pasting of bambara and potato starches with lipids resulted in the formation of type-I V-amylose complexes, with melting temperatures ranging from 98 to 102°C. X-ray diffraction of these complexes showed the crystalline V-amylose pattern with a major peak at 2Q ¼ 19.9° and minor peaks at 2Q ¼ 7.4° and 12.9°. Modification of bambara starch with lipids resulted in reduced digestibility, suggesting their potential application in formulating foods for the management of diabetes.Item In vitro digestibility and some physicochemical properties of starch from wild and cultivated amadumbe corms.(Elsevier, 2015) Naidoo, K; Amonsou, Eric; Oyeyinka, SamsonAmadumbe, commonly known as taro, is an indigenous underutilised tuber to Southern Africa. In this study, starch functional properties and in vitro starch digestibility of processed products from wild and cultivated amadumbe were determined. Starch extracts from both amadumbe types had similar contents of total starch (approx. 95%). Wild and cultivated amadumbe starch granules were polygonal and very small in size (2.7 ± 0.9 m). Amylose content of wild amadumbe (20%) was about double that of cultivated (12%). By DSC, the peak gelatinisation temperatures of wild and cultivated amadumbe starches were 81 and 85 ◦C, respectively. The slowly digestible starch (SDS); 20% and resistant starch (RS); 64% contents of wild amadumbe appeared slightly higher than those of cultivated. Processing amadumbe into boiled and baked products did not substantially affect SDS and RS contents. Estimated glycaemic index of processed products ranged from 40 to 44%. Thus, amadumbe, both wild and cultivated, present some potential in the formulation of products for diabetics and weight managementItem Physicochemical and mechanical properties of bambara groundnut starch films modified with stearic acid.(Institute of Food Technologies, USA., 2016-10-23) Oyeyinka, Samson; Singh, Suren; Amonsou, EricThe physicochemical and mechanical properties of biofilm prepared from bambara starch modified with varying concentrations of stearic acid (0%, 2.5%, 3.5%, 5%, 7%, and 10%) were studied. By scanning electron microscopy, bambara starch films modified with stearic acid (3.5%) showed a progressively rough surface compared to those with 2.5% stearic acid and the control. Fourier transform infrared spectroscopy spectra revealed a peak shift of approximately 31 cm−1, suggesting the promotion of hydrogen bond formation between hydroxyl groups of starch and stearic acid. The addition of 2.5% stearic acid to bambara starch film reduced water vapor permeability by approximately 17%. Bambara starch films modified with higher concentration of stearic acid were more opaque and showed significantly high melting temperatures. However, mechanical properties of starch films were generally negatively affected by stearic acid. Bambara starch film may be modified with 2.5% stearic acid for improved water vapor permeability and thermal stability with minimal effect on tensile strength