Study on sugar profile of rice during ageing by capillary electrophoresis with electrochemical detection

A simple, reliable and reproducible method based on capillary electrophoresis with electrochemical detection, for the determination of sucrose, maltose, glucose and fructose in rice flour was described in this work. Operated in a wall-jet configuration, a 140 μm diameter copper-disk electrode was used as working electrode, which exhibits good response at +650 mV (vs. SCE) for sucrose, maltose, glucose and fructose. Under the optimum conditions, four analytes in 50 mmol/l sodium hydroxide buffer were base-line separated within 15 min. The response was linear over two orders of magnitude, and the detection limit (S/N=3) is 9 × 10−7 g/l, 1.4 × 10−6 g/l, 6 × 10−7 g/l and 1.3 × 10−7 g/l for sucrose, maltose, glucose and fructose, respectively. With this method, a sugar profile study of rice flour was conducted to determine changes produced during ageing. It is observed that there were decreases in the sucrose and maltose contents, and increases in glucose and fructose contents in rice during storage.