超声波喷雾干燥壶瓶枣多糖及其对产品品质的影响

以干燥后多糖的羟基自由基清除能力、含水量和平均粒径为指标,对壶瓶枣多糖的超声波喷雾干燥工艺进行了优化,并对比分析了超声波喷雾干燥、二流体喷雾干燥和真空冷冻干燥对壶瓶枣多糖品质的影响。结果表明,超声波喷雾干燥的最佳工艺条件为:进风温度135℃,进料量16 m L/min,进气压力0.10 MPa,此时出风温度89℃,壶瓶枣多糖产品含水量4.91%,羟基自由基清除率为50.83%,平均粒径9.14μm。羟基自由基清除能力、单糖组成和红外光谱分析表明,3种干燥方式对多糖的活性、单糖组成和官能团没有影响,且多糖主要由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖组成,其物质的量之比为1∶11∶2∶1∶38∶5,羟基自由基清除率为50%左右。通过对多糖产品的微观形态及粒度分布分析可知,冷冻干燥产品以块状和棒针状为主,超声波和二流体喷雾干燥产品均成颗粒状,但是超声波喷雾干燥的产品粒径分布较窄,粒径在2~20μm范围内呈正态分布,优于其他2种干燥技术。

Ultrasonic Spray Drying of Polysaccharides from Ziziphus jujuba Mill. cv. Hupingzao and Its Effect on Product Quality

Taking the hydroxyl radical scavenging capacity, moisture content and particle size distribution of product as indexes, the ultrasonic spray drying( USD) of polysaccharides from Ziziphus jujuba Mill. cv. Hupingzao and the effect of different drying methods, i. e. USD, two-fluid spray drying and vacuum freeze drying, on product qualities were studied. The results showed that the optimum technological conditions of USD were inlet air temperature 135 ℃, feed rate 16 mL/min and intake pressure 0. 10 MPa. Under these conditions, the outlet air temperature, ·OH scavenging rate, moisture content and particle size distribution of the product were 89℃, 50. 83%, 4. 91% and 9. 14μm, respectively. By means of IR spectra, hydroxyl radical scavenging capacity and monosaccharide composition analysis, three drying methods had no effect on the activity, functional group and monosaccharide composition of the product, and the scavenging capacities were all about 50%. The polysaccharide was composed of rhamnose, arabinose, xylose, mannose, glucose and galactose, and their molar ratio was 1∶11∶2∶1∶38∶5. By means of SEM, moisture content and particle size distribution analysis, the products by ultrasonic spray drying and two-fluid spray drying were granular, but the products by vacuum freeze drying were showed in block, bar and needle shape. The particle size distribution of the product of USD was normal distribution with narrow range of 2-20μm. The powder product produced by USD was better than the others.