A Novel Method for Calculating Crystallinity of V‐Type Crystalline Starch by X‐Ray Diffraction

ABSTRACT The crystallinity of V‐type crystalline starch has a significant impact on its functionalities. However, current methods exhibited varying degrees of accuracy in determining the crystallinity, each with their own cons and pros. This study aimed to develop a novel method using x‐ray diffraction (XRD) patterns to precisely calculate the crystallinity of V‐type crystalline starch in three steps: (i) normalizing the XRD intensity of V‐type crystalline starch and amorphous starch at a specific point, (ii) subtracting the normalized XRD patterns of amorphous starch from V‐type crystalline starch to obtain the crystalline subpattern, and (iii) calculating the crystallinity by assessing the area ratio of the crystalline subpattern to the normalized pattern of V‐type crystalline starch. The results found that certain points in the XRD patterns, such as 10°, 15°, 24°, and 25° (2θ), could not be used for the normalization as they resulted in negative peaks in crystalline subpatterns. Notably, the point at 16° (2θ) could be used for the normalization to generate crystalline subpatterns without negative peaks. Furthermore, the crystallinity of V‐type crystalline starch, which was calculated using the proposed method with the point at 16° (2θ) for the normalization, showed a high correlation with the complex index of V‐type crystalline starch (Pearson's coefficient of 0.997), confirming the accuracy of this measurement approach. Findings will provide a feasible pathway to accurately calculate the crystallinity of V‐type crystalline starch.