Effect of Ball Milling Modification on Physicochemical Properties of Foxtail Millet Flour and Noodle Quality

In order to improve the added value of foxtail millet and the processing quality of foxtail millet noodles, the effect of different periods (0.5, 1, 2, 4, 6, and 8 h) of ball milling on the nutritional components, hydration properties, gelatinization properties, rheological properties and crystalline structure of foxtail millet flour and the quality of the resulting noodles was investigated. The correlation between some physicochemical properties and noodle quality was analyzed. The results showed that the crystalline structure of foxtail millet flour was damaged obviously, and the damaged starch content increased significantly with an increase in milling time. It was also found that the amylose content decreased continuously (except for 8 h), and the L* value rose from 77.27 to 81.37. The peak viscosity, trough viscosity, and final viscosity of foxtail millet flour increased from 1478, 665 and 1384 Pa·s to 3271 (ball milling 1 h), 982 (ball milling 2 h) and 2199 (ball milling 2 h) Pa·s (P < 0.05), respectively, and the hydration properties (water-holding capacity and swelling capacity) improved (P < 0.05). Ball milling for 4 h made the gel network structure of dough more compact and resulted in noodles with the best texture and cooking quality. Correlation analysis showed that noodle texture properties (elasticity, stickiness and chewiness) and sensory quality (color, appearance and stickiness) were significantly negatively correlated with amylose content (P < 0.01), but significantly positively correlated with damaged starch and amylopectin contents (P < 0.01). The cooking quality (breakage rate) of noodles was positively correlated with amylose content (P < 0.01), but significantly negatively correlated with damaged starch and amylopectin contents (P < 0.01) and gelatinization viscosity was also strongly correlated with noodle quality. Taken together, the modification of foxtail millet flour by ball milling can be used to produce high-quality foxtail millet noodles.