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In this work, granular cold-water soluble waxy corn starch (N-GCWS) and granular cold-water soluble porous waxy corn starch (P-GCWS) were prepared by waxy corn starch (WS) treated with alcohol-alkali. Starch morphologies, crystal structures, turbidity, cold water viscosity, freeze-thaw stability and oil absorption capacity of N-GCWS and P-GCWS starches were compared. The results showed porous waxy corn starch (PS) was easier to prepare P-GCWS starch than WS to prepare N-GCWS. SEM showed that PS and WS became dent-twisted and tended to flatten with the increase of CWS. After alcohol-alkali treatment, the X-ray diffraction pattern of PS and WS changed from A type to amorphous and pores were remained on the surface of P-GCWS starches granular. Turbidity, freeze-thaw stability, viscosity, oil absorption capacity of N-GCWS and P-GCWS starches was shown higher than that of WS and PS. The oil absorption capacity of P-GCWS was higher than that of N-GCWS. • Granular cold-water soluble porous starch was prepared from porous waxy corn starch. • PS was easier to prepare P-GCWS than WS prepared N-GCWS. • The surface area of P-GCWS was higher than that of N-GCWS. • The oil absorption capacity of P-GCWS was higher than that of N-GCWS. [ABSTRACT FROM AUTHOR]

Abstract: Waxy maize starch was treated by pullulanase debranching and retrogradation at room temperature to produce resistant starch (RS). Physicochemical properties, crystalline structure and in-vitro digestibility of starch samples with different RS content were investigated. Compared with native starch, apparent amylose content of RS products increased. Based on Gel Permeation Chromatography (GPC) the Molecular Weight Distribution (MWD) of resistant starches significantly changed. Scanning Electron Microscopy (SEM) showed that upon pullulanase debranching and retrogradation treatment the granular structure of native starch was destroyed and all RS samples exhibited irregular shaped fragments. Crystal structure of samples changed from A–type to a mixture of B and V–type. The crystallinity of resistant starch also improved as compared with native starch. Moreover, samples with higher resistant starch showed higher relative crystallinity. Differential Scanning Calorimetry (DSC) determination showed that To、Tp、Tc and ΔH all increased which was in agreement with RS content. The resistance of waxy maize starch with Pullulanase treatment to α-amylase digestibility also increased, while the in-vitro digestibility of products decreased. [Copyright &y& Elsevier]

In this work, waxy maize starch nanocrystals were prepared by mixed acid of sulfuric acid and hydrochloric acid for the first time. Physicochemical properties, crystalline structure, and particle size of starch nanocrystals prepared by mixed acid (HSNC) were measured. The results showed that there was no difference in particle morphology, group structure, and surface elements of HSNC and starch nanocrystals prepared by sulfuric acid (SNC), which was a conventional preparation method. The yield of HSNC was lower than that of SNC. However, the preparation time of HSNC was greatly shortened to 1 h which is only 0.83 % of the time (5 d) to prepare SNC by the sulfuric acid, and HSNC showed higher relative crystallinity and smaller size than those of SNC. In addition, when the ratio of sulfuric acid and hydrochloric acid to provide H ion concentration was 1:1 to hydrolyze starch for >1 h, the crystal pattern of HSNC would be changed to V-typed, while the crystal pattern of SNC was still A-typed. Thus, this work provided efficient method for preparing starch nanocrystals is provided, which can replace sulfuric acid hydrolysis to prepare SNC. • Mixed acid were used to prepare starch nanocrystals (HSNC) in 1 h • Starch nanocrystals prepared by mixed acid shortened than conventional preparation • HSNC prepared by mixed acid had higher relative crystallinity and smaller size • The crystal pattern of HSNC prepared >1 h would change to V-typed [ABSTRACT FROM AUTHOR]