Effect of acid hydrolysis on the physicochemical properties of cola starch

摘要

Cola starch fromCola nitida (rubra)was isolated using 1% (w/v) sodium metabisulphite solution and was treated with 0.1 and 0.2 M HCl solution differently at 80 and 100°C, pH (6 to 7.9) and reaction time (30 min to 3 h). The physicochemical and functional properties of the hydrolyzed starch were studied. The hydrolysis reaction presented important changes in the pasting, thermal transition and morphology of the native starch. Reaction time, temperature and concentration of the acid were observed to influence the reactions. The acid modified starch has the following properties; swelling 6.13 to 7.21% solubility 14.83 to 16.65% and amylose content 17.28 to 21.69%, while the corresponding values for the native cola starch were swelling 8.85%, solubility 7.48% and amylose 24.76%. The rapid visco analysis (RVA) of the acid modified starch demonstrated low peak viscosity ranging from 52.71 to 197.22 as against 314.42 reported for the native starch. Breakdown viscosity and the setback values also exhibited the same decreasing trend; 30.24 to 73.17 and 10.18 to 34.91 respectively, as against that of native cola starch that has a breakdown and setback viscosity of 179.25 and 74.42 respectively. The observed trends are consistent with other modified starches that have found useful applications in pharmaceutical, food and confectionary industries.