Strategy for Enhancing Wheat Drying Efficiency and Flour Quality: Hybridization of Tempering and Hot Air Drying

The moderate processing of wheat is increasingly valued. One of the technological means to achieve moderate processing is the hybridization of tempering and hot air drying for postharvest wheat. The initial moisture content at onset of tempering (IMCOT) of wheat significantly influences the efficiency of hot air drying as well as the yield and quality of wheat flour. This study investigates the effects of varying IMCOT and tempering durations on the drying characteristics of wheat, the flour yield, the flour properties, and the properties of flour slurries. The findings revealed that tempering treatments reduced the drying time and altered the pasting characteristics of the flour slurries. This phenomenon could be attributed to the alteration of the kernel structure and starch destruction caused by tempering treatment. Tempering significantly (P < 0.05) affected the protein content and wet gluten content of wheat flour (WF). For the effect of IMCOT, the shortest drying time (35 min) was observed at an IMCOT of 0.17 g/g d.b., while the highest wet gluten content of WF was achieved when it was 0.19 g/g d.b. The lowest breakdown value (908.00 Brabender Units, BU) and highest setback value (811.50 BU) of WF were observed at an IMCOT of 0.19 g/g d.b. For the effect of tempering duration, the shortest drying time (35 min) was achieved at a tempering duration of 40 min. Tempering duration improved the whiteness and brightness of the flour, as well as increased its protein content. Considering the drying efficiency and the quality attribute, the optimal tempering condition was the IMCOT of 0.19 g/g d.b. and a tempering duration of 40 min.