Preparation and structure characterization of linear long-chain dextrin obtained from pullulanase debranching of cassava starch

A relatively simple and economical method to prepare linear long-chain dextrin (LLD) was created, with a resulting product that could act as a high-amylose starch for a variety of downstream applications. Native cassava starch was chosen as the starting material due to its inexpensive price and low-gelatinization temperature. A pretreatment with NaOH solution was applied to increase the susceptibility of cassava starch to pullulanase attack. The apparent amylose content of the final LLD product was extremely high (above 90%), as determined by the iodine binding colorimetric method. Using HPLC, the optimum amount of enzyme was determined to be 25U pullulanase per gram of starch. The structure of the LLD was found to be a V6I crystalline type, and this was confirmed by multiple physical techniques, including X-ray powder diffraction, solid-state nuclear magnetic resonance, and Fourier transform infrared. Overall, this study could promote further investigations into the efficient preparation and characterization of amylose products.