微波处理时间对大豆高温脱脂豆粕品质的影响

为了改善生产大豆蛋白质粉的原料高温脱脂豆粕的品质，提高工艺控制的稳定性，可靠性。本文分析了在微波功率20 kW，风速2.5 m/s，物料厚度20 mm情况下，微波处理4~6 min的过程对高温脱脂豆粕的含水率、温度、菌落总数、溶水后的颜色及其大豆蛋白的二级结构的影响，进而指导用于大豆蛋白粉生产的高温脱脂豆粕的生产及应用。结果表明:微波处理时间4~6 min时，含水率降低速度为1.51%/min；微波处理5.45 min时，温度能够控制在103 ℃，微生物的杀灭率达到96.8%，菌落总数达到100 CFU/g；微波处理时间在4.62~5.45 min之间时，水溶液红色值比较稳定，亮度和黄色值略有变化，色泽较好；微波时间≥5 min时，脲酶活性达到阴性，满足婴幼儿食品的要求；微波处理对蛋白二级结构有显著的影响，在4.29~5.45 min之间时，α螺旋向β转角转化，进而消失，β转角量快速增加；微波时间在5.45~6 min之间时，β转角迅速向α螺旋转化；整个微波处理过程中，β折叠只有小幅度的变化，相对稳定。通过微波处理可有效地控制高温脱脂豆粕的水分、颜色、菌落总数、脲酶活性、改善大豆蛋白的二级结构，对提高大豆高温脱脂豆粕的品质，扩大应用领域具有积极意义。

Effects of Microwave Treatment Time on the Quality of Soybean High-temperature Defatted Soybean Meal

In order to improve the quality of high-temperature defatted soybean meal, which is the raw material for producing soybean protein powder, and improve the stability and reliability of process control. Under the condition of microwave power of 20 kW, wind speed of 2.5 m/s, and material thickness of 20 mm, the effects of microwave treatment for 4 to 6 min on the moisture content, temperature, total number of colonies, color after water-dissolving and the secondary structure of soybean protein in high-temperature defatted soybean meal were analyzed. It could be used to guide the production and application of high temperature defatted soybean meal for soybean protein powder production. The results showed that: When the microwave treatment time was between 4 and 6 min, the water content decreased at a rate of 1.51%/min; when the microwave treatment time was 5.45 min, the temperature could be controlled at 103 ℃, the killing rate of microorganisms reached 96.8%, and the total number of colonies reached 100 CFU/g; when the microwave treatment time was between 4.62 and 5.45 min, the red value of the aqueous solution were relatively stable, the brightness and yellow value changed slightly, and the color was good; when the microwave time was ≥5 min, the urease activity was negative, which met the requirements of food for infants and children; microwave treatment had a significant effect on the secondary structure of the protein. When the microwave time was between 4.29 and 5.45 min, the α-helix transformed to the β-turn and then disappeared, and the amount of the β-turn increased rapidly; when the microwave time was between 5.45 and 6 min, the β-turn was rapidly transformed to the α-helix; the β-sheet changed only in small amplitudes and was relatively stable during the entire microwave treatment process. Microwave treatment can effectively control the moisture, color, total number of colonies, urease activity of high-temperature defatted soybean meal, and improve the secondary structure of soybean protein, which is of positive significance for improving the quality of high-temperature defatted soybean meal and expanding the application field.