Revealing the Structural Organization of Starch From Native Potatoes Using Polarization-Resolved Second Harmonic Generation Microscopy.

Abstract

Starch from a single botanical source can exhibit variations in physicochemical properties in both its native and hydrolyzed forms. This study examined the structural and functional characteristics of starch from five potato varieties of India. In vitro enzymatic hydrolysis was employed to determine the dextrose equivalent profile of each starch type. The amylose content among the five potato varieties ranged from 17.5 and 25%. Optical microscopy revealed that the native starch granules were ovoid or elliptical in shape. X-ray diffraction analysis confirmed the presence of starch crystallinity and identified spectral peaks characteristic of A-type starch crystals in the native form. Fourier transform infrared spectra indicated common stretching and deformation of bonds in all native starches. Differential scanning calorimeter endotherms showed the highest and lowest gelatinization peak temperatures among the starch varieties. Additionally, polarization-resolved second harmonic generation microscopy was employed to image the starch granules and obtain high-resolution structural insights, revealing distinctive patterns of starch crystallinity. The findings of this study can help to optimize the usage of potato starch in food and nonfood industries. Additionally, understanding the control points of starch digestion and genetically tailoring potato varieties with different digestibility profiles could be beneficial for nutraceutical applications.