Molecular structure, morphological, and physicochemical properties of highlands barley starch as affected by natural fermentation.

The influence of natural fermentation on the highlands barley starch chemical structure, morphological, physicochemical, and thermal properties was studied. The findings showed that fermentation had no impact on starch fine structure but it decreased the molecular-weight from 2.26 to 1.04 × 108 g/mol in native highlands barley and after 72 h fermentation (FHB72) respectively. Also, it decreased amylopectin long-chains (B1 and B2) while increased short-chains. The intensity ratio of FT-IR at 995/1022 and 1047/1022 bands were found to be higher as the time of fermentation progressed, and the highest absorption-intensity at 3000-3600 cm-1 and higher swelling capacity were noticed in the starch of FHB72. During fermentation, pasting peak, final and setback viscosities were decreased. Microscopically, granules with more pores, damaged, cracked, and no growth rings were found in starches isolated after 48 h and 72 h of fermentation. This study indicated that fermentation up to 72 h is an effective method to modify highlands barley starch.