Elucidating the impact of barley β-glucans with different molecular weights on the retrogradation behavior of normal and waxy highland barley starches: Physicochemical and mechanistic insights.

Barley β-glucan could regulate the retrogradation behavior of highland barley starch (HBS). However, the mechanisms of barley β-glucan with distinct molecular characteristics in inhibiting starch retrogradation remain unclear. This study evaluated the effects of β-glucans with different molecular weights (179 kDa, 251 kDa, and 495 kDa) on the physicochemical properties of normal (NHBS) and waxy HBS (WHBS). Results indicated that all β-glucans inhibited HBS retrogradation during 14-day storage at 4 °C, and high molecular weight β-glucan (HBG) exerted the most profound inhibitory effect. Specifically, β-glucans delayed the water loss and the increase in hardness of starch gels during storage. Notably, NHBS-HBG and WHBS-HBG exhibited the lowest degree of retrogradation (9.28 and 3.07%) and relative crystallinity (10.53 and 14.71%) after 14 days of storage. In contrast, the control NHBS and WHBS showed higher retrogradation degree (13.11% and 3.65%) and relative crystallinities (14.10% and 16.21%). β-Glucans limited water migration in gels, which was attributed to the interactions between HBS and β-glucans. The complexing index and FTIR confirmed that the complexation between HBS and HBG was the strongest, mainly driven by hydrogen bonds. Furthermore, 1H NMR and SEM demonstrated that these interactions intensified over time, thereby effectively hindering the rearrangement of starch molecules. The study elucidates the underlying mechanism of HBG-mediated regulation of HBS retrogradation, which is crucial for extending the shelf-life of HBS-based products and expanding the application properties of HBG.