Research on the quality characteristics of low-gluten wheat front-end heart mill flour and the in vitro protein digestibility for infants

This study investigated eleven first-pass heart-milled flours within the low-gluten wheat flour milling system. The quality characteristics of these flours were evaluated, including protein content, wet gluten content, particle size, processing precision, whiteness, farinograph properties, and gelatinization properties. Additionally, the in vitro protein digestibility of these flours for infants was assessed. The objective was to compare the properties and digestibility of the first heart-milled flours, and using digestibility as the primary criterion while considering flour quality characteristics, identify wheat flour raw materials suitable for infant cereal complementary foods. The results indicated that the ash, protein, and gluten contents of the flours obtained from the front - end heart milling process were relatively low. For 1M₁, 1M₂, 2M₁, and 2M₂, both damaged starch content and brightness decreased. Solvent retention capacity and particle size gradually declined as the milling process advanced. Water absorption and weakening degree were higher in 1M₁ and 2M₁ compared to 1M₂ and 2M₂. Peak viscosity, minimum viscosity, and final viscosity for both 1M and 2M exhibited an upward trend. In terms of in vitro static digestion rates for infants, flours from the 1M₁ and 2M₁ systems demonstrated higher rates than those from the 1M₂ and 2M₂ systems. Notably, the upstream flour of 2M₁ exhibited a relatively high protein content, a high protein digestion rate, and significantly lower breakdown and setback values. Compared to the upstream flour of 1M₁, which had a similar digestion rate, the 2M₁ upstream flour demonstrated superior flour quality characteristics. Therefore, among the flours obtained from the front - end heart milling process, the 2M₁ upstream flour is more suitable as a raw material for easily digestible infant flour.