谷朊粉对冻干枣粉抑制吸湿作用研究

Study of wheat gluten on hygroscopicity inhibition of freeze-dried jujube powder

中文关键词:  枣粉  谷朊粉  水分迁移  吸湿等温线

英文关键词:jujube powder  wheat gluten  moisture migration  hygroscopic isotherm

中文摘要:

      目的 研究谷朊粉对冻干枣粉吸湿特性的影响。方法 将谷朊粉与枣浆按不同比例均匀混合, 真空冷冻干燥后粉粹, 过60目筛制备不同配比的冻干枣粉, 通过吸湿动力学曲线、吸湿等温线、接触角、低场核磁共振、宏观和扫描电镜图片等分析方法评价其湿特性。结果 谷朊粉显著降低了冻干枣粉的平衡含水率。吸湿等温结果表明, 红枣与谷朊粉为10:0、7:3、1:1、3:7 (m:m)样品的吸湿等温类型属“J”型增长, 而0:10 (m:m)样品的属“S”型增长, 表明谷朊粉的添加并未改变冻干枣粉吸湿等温类型; 接触角随着谷朊粉的添加量的增加, 其值从31.22°增大到80.33°, 说明谷朊粉可以减弱冻干枣粉的表面润湿性。从宏观和扫描电镜图中可知, 冻干枣粉结块现象随着谷朊粉的添加量的增大而逐渐减轻。低场核磁共振结果显示, 谷朊粉降低自由水的含量, 减少水分向高自由度方向的迁移程度。结论 一定量的谷朊粉能够有效抑制冻干枣粉的吸湿, 从而缓解结块的发生, 保持流动性和分散性, 进而提高冻干枣粉的品质。

英文摘要:

      Objective To study the effect of wheat gluten on hygroscopicity of freeze-dried jujube powder. Methods The wheat gluten and jujube pulp were mixed evenly in different proportions. Powder after vacuum freeze -drying, jujube powder with different proportions was prepared by passing through a 60-mesh sieve. The hygroscopicity were evaluated by analysis methods such as hygroscopic kinetic curve, hygroscopic isotherm, contact angle, low-field nuclear magnetic resonance , macroscopic and scanning electron microscope images, etc. Results Wheat gluten significantly reduced the equilibrium moisture content of freeze-dried jujube powder. Hygroscopic isotherm results showed that the hygroscopic isotherm type of jujube and wheat gluten at 10:0, 7:3, 1:1 and 3:7 (m:m) samples was “J” type growth, while the hygroscopic isotherm type of 0:10 (m:m) sample was “S” type growth. Thus, the addition of wheat gluten did not change the hygroscopic isotherm type of freeze-dried jujube powder; the contact angle increased from 31.22° to 80.33° with the addition of wheat gluten, indicating that wheat gluten could reduce the surface wettability of freeze-dried jujube powder. Macroscopical and scanning electron microscopy images showed that the aggregates of freeze-dried jujube powder was gradually reduced with the increase amount of wheat gluten. Low-field nuclear magnetic resonance results showed that wheat gluten reduced the content of free water and inhibited the water to migrate towards a high degree of freedom. Conclusion A certain amount of wheat gluten can inhibit the hygroscopicity of freeze-dried jujube powder effectively, thereby alleviating the occurrence of caking, maintaining its fluidity and dispersity, improved the quality of freeze-dried jujube powder.