Preparation of V-type granular starch in natural deep eutectic solvent and its physicochemical properties and in...

To address stringent operating conditions and reagent toxicity in conventional preparation methods, a new methodology employing natural deep eutectic solvent (choline chloride/malic acid) as media was developed to produce V-type granular starch. Analyses were conducted on the structure, hydration characteristics and in vitro digestibility of the obtained V-type granular starch. When corn starch was heated in the natural deep eutectic solvent at 100 °C (boiling water bath) for 45 min, its granular morphology was maintained, but volume average particle size increased and average molecular weight decreased significantly. The A-type crystalline structure of corn starch transformed completely into V-type, confirmed by X-ray diffraction and differential scanning calorimetry analysis. The obtained V-type granular starch had better swelling capacity, water holding capacity and cold water solubility than native corn starch, and it also showed better antidigestive characteristic. Incorporating decanoic acid in the V-type granular starch preparation produced starch-decanoic acid inclusion complexes with a complex index of 15.08%. The formation of these complexes not only endowed the product with a more typical V-type crystalline structure and higher relative crystallinity, but also enhanced its swelling capacity and water holding capacity, additionally the digestion rate of the product decreased further. These findings provide information for the application of natural deep eutectic solvent in V-type granular starch preparation.