喷雾干燥与真空冷冻干燥对核桃粕红枣复合粉品质的影响

以核桃粕、红枣为原料,采用喷雾干燥、真空冷冻干燥2种方式制备核桃粕红枣复合粉,对其集粉率、水分含量、蛋白质含量、堆积密度、流动性、溶解性、色差值、微观结构、蛋白质体外模拟消化、热稳定性进行探究。结果表明:真空冷冻干燥集粉率明显高于喷雾干燥,但是耗时长,水分含量和堆积密度高于喷雾干燥,休止角低于喷雾干燥,说明真空冷冻干燥核桃粕红枣复合粉不易贮藏、溶解性较差,但是流动性好;喷雾干燥所得复合粉颜色比较鲜亮。2种复合粉热稳定性相似,但从整体来看,喷雾干燥复合粉蛋白质营养价值更高。观察复合粉微观结构,喷雾干燥复合粉呈球状,有利于颗粒与水分接触;真空冷冻干燥复合粉形状不规则,颗粒之间出现黏结,不利于颗粒与水分接触。

Effects of spray drying and vacuum freeze-drying on the quality of walnut meal and jujube compound powder

The compound powder of walnut meal and jujube was prepared by spray drying and vacuum freezing drying with walnut meal and jujube as raw materials. Investigated the powder yield, moisture content, protein content, bulk density, fluidity, solubility, color difference value, microstructure, simulated digestion of protein in vitro and thermal stability. The results showed that the powder yield of vacuum freeze-drying was significantly higher than that of spray drying, but the time was longer, the moisture content and bulk density were higher than spray drying, and the rest angle was lower than spray drying. It shows that vacuum freeze-drying of compound powder was not easy to store and had poor solubility, but had good fluidity. The compound powder obtained by spray drying is brighter in color. There was no significant difference in the thermal stability of the two powders, but on the whole, the value of protein nutrition was higher. The surface microstructure of the two kinds of composite powders was observed. The results showed that the spray drying composite powder was spherical, which was beneficial to the contact between particles and water. The vacuum freeze-drying composite powder is irregular in shape, and there is adhesive between particles, which is not conducive to the contact between particles and water.