Distinct viscosity and gel hardness obtained by ball-milled konjac flour: Insights into physicochemical properties, structure and gel properties

Ball-milling, a sustainable mechanical processing technique, was employed to modify konjac flour to obtain distinct viscosity and gel hardness. Additionally, structural alterations were mechanistically linked to the distinct viscosity and gel hardness of four types of ball-milled flour. The results showed that the decline in viscosity was correlated with the reduction in molecular weight (M_w) (p < 0.05). The enhancement of gel hardness was associated with particle size distribution (D₉₀, p < 0.05). Optimal gel hardness (8.02-fold) after ball-milling resulted from synergistic effects of optimized dimensions (D₉₀ = 125.6 μm), combined with a high specific surface area (212.38 m²/g), low M_w (8.57 × 10⁶ g/mol) and preserved ordered structures with an unchanged crystallinity index (1.72). Notably, differential scanning calorimetry significantly improved thermo-stability of ball-milled flour. Ball-milling induced depolymerization through frictional, collisional, impact and shear forces, leading to mechanical fragmentation and particle size reduction with surface microcracks and pronounced agglomeration of fine particulates.