Impact of Wheat Tempering Conditions on Flour Particle Size and Thermo-Mechanical Properties

Abstract

Background and Objective: In the baking and milling sectors, the rheological qualities of wheat flour and dough are crucial since they determine the flour's quality and processing characteristics. Tempering conditions influence particle sizes and milling yield, which affect flour properties. This study evaluates the impact of tempering conditions-temperature (20-60EC) and time (6-18 hrs)-on flour particle size and thermo-mechanical properties. Materials and Methods: The study analyzed flour samples obtained from wheat grains tempered at different conditions. Particle size distribution was measured using standard sieving techniques, with values recorded for D10, D50, D90, D(3,2) and D(4,3). Mixolab analysis was conducted to assess the rheological properties of flour, including protein weakening (torque C2) and starch behavior. Dough stability was evaluated based on deformation resistance over time. Data were analyzed using ANOVA and mean differences were assessed via Tukey's test at p<0.05. Results: Results indicated that particle size decreased as tempering time and temperature decreased. The average particle size of wheat flour samples ranged from 14.05-8.65 µm (D10), 60.00-63.50 µm (D50), 113.50-96.50 µm (D90), 28.75-5.95 µm (D(3,2)) and 61.55-66.50 µm (D(4,3)). Torque C2, an indicator of protein weakening, varied between 0.44 and 0.56 Nm, demonstrating that tempering conditions influenced flour protein properties. The Mixolab analysis showed that starch properties of conditioned wheat resulted in slightly lower rheological performance than standard flour. Dough stability was highest in the control sample, improving deformation resistance by 9.42 min, while wheat conditioned at 60EC for 12 hrs (T3T2 sample) exhibited the lowest dough stability (6.51 min). Conclusion: Tempering conditions significantly affected flour particle size and thermo-mechanical properties. Lower tempering temperatures and shorter durations resulted in finer flour particle sizes. Additionally, flour from conditioned wheat showed variations in dough stability and protein weakening, with higher tempering temperatures leading to reduced dough stability. Understanding these effects can help optimize tempering conditions for improved flour quality.