湿法研磨结合喷雾干燥制备苦荞麸皮超微粉工艺优化

研究苦荞麸皮超微粉的制备工艺，以总黄酮含量为考察指标，采用单因素-正交试验优化确定湿法研磨最佳工艺条件；以集粉率为考察指标，采用单因素-响应面试验对喷雾干燥工艺进行优化。结果表明，研磨转速2 600 r/min，研磨时间1.0 h，料液比1:7（g/mL）时，测得麸皮粉的总黄酮含量为8.55 g/100 g，高于对照组的4.93g/100g。采用响应面优化后的干燥工艺进行验证试验，即进口温度164℃、进风量0.43 m3/min、料液浓度5.85%和进样流量620 mL/h，苦荞麸皮粉的集粉率为68.72%。扫描电镜结果显示最佳制备工艺制备的超微粉粒径更小，组织结构受到严重破坏，淀粉、蛋白质等小颗粒得到释放。湿法研磨结合喷雾干燥制备苦荞麸皮超微粉，集粉率较高，总黄酮含量有显著增加，超微粉微观结构发生明显变化。

Preparation Process Conditions Optimization of Tartary Buckwheat Bran Ultrafine Powder by Wet Grinding combined with Spray Drying

In this investigation, the preparation process of tartary buckwheat bran ultrafine powder was investigated. Firstly, taking the total flavonoid content as the evaluation index, the optimal wet grinding process conditions were optimized by using the single factor-orthogonal experiment. Then, using the powder collection rate as the evaluation index, the spray drying process conditions were optimized through the single factor-response surface test. Results indicated that the highest total flavonoid content (8.55 g/100 g) of the bran powder was obtained under the conditions including the grinding speed of 2600 r/min, the grinding time of 1.0 h, and the material-to-liquid ratio of 1:7 (g/mL). While, the content of total flavonoid content of control sample was only 4.93g/100g. Moreover, the drying process conditions optimized by the response surface were used for the verification test. The obtained best conditions included the inlet temperature of 164°C, the air flow rate of 0.43 m3/min, the material liquid concentration of 5.85%, and the sample flow rate of 620 mL/h. Under this process conditions, the powder collection rate of the actual tartary buckwheat bran powder is 68.72%, which is highest among all the treatments. Scanning electron microscopy results indicated that the ultrafine powder prepared by the best preparation process exhibited the smaller particle size than that of other treated particles. It also observed that the tissue structure of these particles was severely damaged, and the release of small particles such as starch and protein was also found. In conclusion, using the technology of wet grinding combined with spray drying, the high powder collection rate and ideal total flavonoid content were found, and significant change of the particles microstructure was observed.