Abstract

Modified rice flours were obtained by high-impact milling. A factorial design was performed in a planetary ball mill varying rotational speed (450–650 rpm) and milling time (10–40 min) while milling energy (0.3–4.3 kJ/g), particle size distribution (PSD) of rice flour, and changes in starch structure were recorded. The effect of rotational speed and time on milling energy was satisfactorily modeled by the Response Surface Methodology. Modified flours presented bimodal PSD unlike that of the control flour, which was monomodal with a lower size dispersion. A significant reduction of D[4,3] (mean diameter) was observed as the milling energy increased. However, the effect of milling energy on PSD was dependent on milling speed. Classical milling equations provided a satisfactory fit of energy-size records at low speed (450 rpm), but at higher speed, a poor adjustment was obtained due to the increasing relevance of heat dissipation. The empirical milling equation based on linear or exponential relationships between milling energy and size reduction ratio provided a good fit for experimental data. Significant correlations between milling energy and damaged starch, crystallinity, and gelatinization degree were found. The proposed mathematical models are a contribution to the milling process design for specific modifications of rice flour.

摘要

通过高冲击碾磨获得改性米粉。在行星球磨机中进行因子设计，改变转速（450-650 rpm）和研磨时间（10-40 min），同时研磨能量（0.3-4.3 kJ/g）、米粉的粒度分布（PSD）、并记录淀粉结构的变化。旋转速度和时间对铣削能量的影响通过响应面方法令人满意地建模。与对照面粉不同的是，改性面粉呈现双峰 PSD，对照面粉是具有较低尺寸分散的单峰。随着研磨能量的增加，观察到 D[4,3]（平均直径）显着降低。然而，研磨能量对 PSD 的影响取决于研磨速度。经典铣削方程在低速（450 rpm）下提供了令人满意的能量大小记录拟合，但在更高的速度下，由于散热的相关性越来越高，因此调整不佳。基于铣削能量和尺寸减小率之间的线性或指数关系的经验铣削方程为实验数据提供了良好的拟合。发现碾磨能量与受损淀粉、结晶度和糊化度之间存在显着相关性。所提出的数学模型有助于米粉特定改性的碾磨工艺设计。和糊化度。所提出的数学模型有助于米粉特定改性的碾磨工艺设计。和糊化度。所提出的数学模型有助于米粉特定改性的碾磨工艺设计。