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

Rice starch was debranched with the debranching enzyme pullulanase. Anion-e xchange chromatography with pulsed amperometric detection (AEC-PAD) was use d to study effect of time on the degree of enzyme catalyzed debranching. Th e stability of starch sample in different starch solvents during extended s torage was evaluated. Lyphylized, non-debranched starch samples were prepar ed in 0.0375 M HCl, 0.0375 M NaOH and water, followed by heating at 121 deg reesC for 30 min. Samples were stored for 21 days. HCl hydrolyzed the starc h. Starch samples prepared in water were also unstable with progressively i ncreasing peak areas up to 21 days. Starch samples prepared in NaOH are most stable on storage. Lower concentra tion (0.009, 0.0046, 0.0023, and 0.0012 M) of HCl hydrolyzed freshly prepar ed non-debranched starch autoclaved at 121 degreesC for 30 min in respectiv e concentration of HCl to different degrees dependent on the concentration of HCl used. Starch samples prepared in water from freshly cooked or lyphol ized 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 w ere removed at various time intervals and analyzed immediately after sampli ng using water as the solvent.