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High amylose corn starch (HACS)-oat β-glucan (OBG) complex was prepared by ball milling treatment. The morphology and structure of the samples were characterized, and the digestibility of the samples was studied. SEM analysis showed that the grain structure of oat β-glucan-starch after ball milling showed an irregular aggregate shape. The rheological results indicated that the apparent viscosity of the solution of HACS-OBG complex prepared by ball milling, with the values of both G′ and G″ decreasing on the increase of OBG addition. Multi-scale structure analysis showed that the disorder of the crystal structure and short-range structure of the HACS-OBG complex would lead to the decrease of the double helix structure content. In terms of digestibility, the RDS of the complex decreased from 75.88 % to 66.26 %, which suppressed the digestibility of starch. Molecular docking and quantum chemistry techniques further demonstrated the strong hydrogen bond interaction between HACS and OBG and the inhibition rate of OBG on the enzyme, which was conducive to the slow digestion of HACS-OBG complex. Therefore, ball milling treatment can promote the binding of OBG to starch, which may be an effective method for postprandial blood glucose control. • Starch - Oat-β-glucan complexes were prepared by ball milling treatment. • High amylose corn starch - Oat-β-glucan complexes cannot form distinct crystallites. • Oat-β-glucan accelerated the disorder of starch short-range ordered structure. • Complexation with Oat-β-glucan can decrease the digestibility of starch. [ABSTRACT FROM AUTHOR]

The digestibility of starch-based foods is receiving increased attention. To date, the full understanding of how including L-theanine (THE) can modify the structural and digestive properties of starch has not been fully achieved. Here, we investigated the multi-scale structure and digestibility of maize starch (MS) regulated by THE in ultrasound field and the molecular interactions. Ultrasound disrupted the structure of starch granules and opened the molecular chains of starch, promoting increased THE binding and producing more low-order or disordered crystal structures. In this case, the aggregation of starch molecules, especially amylose, was reduced, leading to increased mobility of the systems. As a result, the apparent viscosity, G', and G" were significantly decreased, which retarded the starch regeneration. Density functional theory calculations indicated that there were mainly non-covalent interactions between THE and MS, such as hydrogen bonding and van der Waals forces. These interactions were the main factors contributing to the decrease in the short-range ordering, the helical structure, and the enthalpy change (ΔH) of MS. Interestingly, the rapidly digestible starch (RDS) content of THE modified MS (MS-THE-30) decreased by 17.89 %, while the resistant starch increased to 26.65 %. These results provide new strategies for the safe production of resistant starch. • Ultrasonication opened the double helix structure of maize starch and facilitated interbinding with L-theanin. • During ultrasound treatment, L-theanin accelerated the disorder of the short-range ordered structure of starch. • Hydrogen bonding and van der Waals forces were the main non-covalent bonds between maize starch and L-theanin. • The interaction of maize starch with L-theanin decreased the digestibility of starch. [ABSTRACT FROM AUTHOR]

In this study, high amylose maize starch(HAMS)was treated by Hydrothermal-alkali. SEM, SAXS, XRD, FTIR, LC-Raman, 13C CP/MAS NMR, GPC and TGA were used to study the changes in the granules and structure of HAMS. The results show that the granule morphology, lamellar structure, and birefringence of HAMS remained intact at 30 °C and 45 °C. With increasing temperature, the starch granules are fragmented, and the crystallinity, DD, FWHM values, molecular weight, and thermal stability of HAMS decrease. The double helical structure dissociated, and the content of amorphous regions increased, indicating the from order to the disorder of the HAMS structure. A similar annealing behavior occurred in HAMS at 45 °C, with the rearrangement of amylose and amylopectin occurring. At 75 °C and 90 °C, the short-chain starch produced by chain breakage regroups to form an ordered double helix structure. In general, the granule structure level of HAMS was damaged to different degrees at varying temperatures. HAMS showed gelatinization behavior in alkaline solutions when the temperature is 60 °C. This study expects to provide a model for the gelatinization theory of HAMS systems. [Display omitted] [ABSTRACT FROM AUTHOR]