Effects of various thermal processing methods on the gel properties of hulless barley β-glucan

Thermal processing of barley grains is a useful technique for modelling the physicochemical properties of β-glucans and their food applications. This study investigated the impacts of different thermal processing techniques-including flaking-roasting (FR), stir-frying (SF), steam flash-explosion (SFE), and popping expansion (PE)-on the gelation properties of hulless barley β-glucan. Results showed that PE-β-glucan showed the highest molecular weight (M_w 5243.6 ± 0.3 kDa), water holding capacity, solubility, zeta potential, gel stability, and texture properties, followed by native, SF-, and FR-β-glucan. However, SFE-β-glucan (lowest M_w, 89.9 ± 0.2 kDa) failed to gel even at 60 mg/mL. Microstructure observations by atomic force microscope (AFM), confocal laser scanning microscope (CLSM), and transmission electron microscopy (TEM) indicated that PE-induced chain conformation changes primarily augmented cluster stability of β-glucan, strengthening gelation. Hence, β-glucan gel performance is jointly governed by molecular weight and chain conformation, both significantly altered by thermal processing.