How to calculate starch lamellar features with improved accuracy by small angle X-ray scattering

Starch lamellar structures unraveled by small angle X-ray scattering (SAXS) have been critically correlated with its functionalities. However, the lamellar features calculated by the classical linear correlation function based on SAXS data are not well convincingly analyzed, because the thickness of amorphous lamellae calculated by previous studies is smaller than the smallest detectable size extrapolated from the selected data. The main reason causes this unconvincing result is the unsuitable data used. Appropriate data are selected in this study for better portraying the linear correlation function profile and then suitable principles are proposed to convincingly analyze starch lamellar features. For verifying the validity of selected data and calculated results, two criterions are established, i.e., (i) the thickness of amorphous lamellae evaluated from the correlation profiles should be larger than the smallest detectable size extrapolated from the selected data according to the Woolf-Bragg's equation and (ii) the value of the thickness of semi-crystalline lamellae calculated from the linear correlation function profile should close to that obtained from the original SAXS curve. Accordingly, the data of 0.10-2.75 nm^-1 are optionally selected for calculating starch lamellar parameters. The results of this study provide a promising pathway to unravel starch lamellar features with improved accuracy.