Application of aerosol‐spray deposition for determination of fine structure of barley starch using atomic force microscopy

Abstract

Abstract Starch samples extracted from barley cultivars with varying AM concentrations were imaged by AFM using intermittent contact mode. Two different deposition methods were used: a simple solution drop and an aerosol spray deposition. Using the drop deposition method, starch appeared mainly as small particles and aggregated globules, with average heights of 1.8 ± 0.2, 2.7 ± 0.7, and 5.5 ± 1.0 nm, for starch solutions containing increased (38%), normal (25.8%), and undetectable (0%) AM, respectively. The aerosol spray deposition method allowed analysis of individual biopolymer chains of AM and biopolymer fibrils of AP. The image of normal starch showed individual AM chains with an average height of 0.8 ± 0.2 nm, and an average contour length of 178 ± 127 nm. For increased AM starch, the height of individual AM chains was similar to normal starch, but the average contour length was shorter (140 ± 70 nm). All barley starches showed fibril bundles of AP with average heights of 1.9 to 2.9 nm and lengths in the micron size range.