2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Most amylose quantification methods are difficult to perform and are subject to uncertainties. Despite years of use, a systematic study of the most popular techniques has not been performed. Pure amylose and amylopectin fractions were purified from four starch sources: potato, rice, wheat and corn. Amylose and amylopectin fractions from each source were mixed (dry weight basis) to obtain samples with 10, 20, 30, 50, 80% amylose contents. Four amylose determination methods were performed, including iodine binding, Megazyme(^TM) amylose/amylopectin, high performance size exclusion chromatography (HPSEC) and differential scanning calorimetry (DSC). For the DSC procedure, L-alpha-Lysophosphatidylcholine (LPC) was used to specifically form a complex with amylose during the cooling phase. Results from DSC are reproducible; the overall C.V. was approximately 4.7%. The slopes of standard curves from the different starch sources didn't vary significantly (P<0.05). HPSEC analysis was improved by maximizing starch dispersion, without depolymerization, by using urea-DMSO. Amylose dispersion was increased approximately 10% (over DMSO alone), and amylopectin dispersion was increased 33%. The limitation and benefits of each method will also be outlined.