Evaluation of debranched rice starch sample preparation methods for anion-exchange chromatography with pulsed amperometric detector

摘要

Rice starch was debranched with the debranching enzyme pullulanase. Anion-exchange chromatography with pulsed amperometric detection (AEC-PAD) was used to study effect of time on the degree of enzyme catalyzed debranching. The stability of starch sample in different starch solvents during extended storage was evaluated. Lyphylized, non-debranched starch samples were prepared in 0.0375 M HCl, 0.0375 M NaOH and water, followed by heating at 120deg C for 30 min. Samples were stored for 21 days. HCl hydrolyzed the starch. Starch samples prepared in water were also unstable with progressively increasing peak areas up to 21 days. Starch samples prepared in NaOH are most stable on storage. Lower concentration (0.009, 0.0046, 0.0023, and 0.0012 M) of HCl hydrolyzed freshly prepared non-debranched starch autoclaved at 121deg C for 30 min in respective concentration of HCl to different degrees dependent on the concentration of HCl used. Starch samples prepared in water from freshly cooked or lypholized non-waxy and waxy starch samples were also unstable with progressively increasing peak areas up to 7 days of storage. To determine the effect of time on degree of enzyme catalyzed debranching, debranched starch samples were removed at various time intervals and analyzed immediately after sampling using water as the solvent.