木枣多糖的理化特性研究

为充分利用红枣资源，挖掘不同采收期枣果的加工利用价值，以木枣为试材，对比分析白熟期、半红期、全红期三个采收期木枣经自然晾干、热风干燥、真空冷冻干燥后营养、色泽、质地品质指标的变化。结果表明：相同干制方式下白熟期木枣V_C、粗纤维、黄酮、三萜类化合物的含量高于半红期，半红期的高于全红期；白熟期木枣可溶性糖和多糖含量显著（P<0.05）低于半红期，半红期的显著（P<0.05）低于全红期；除了可溶性糖外，三个采收期木枣真空冷冻干燥后营养功能成分含量最高，但白熟期和半红期木枣自然晾干或热风干燥后可获得较全红期枣果真空冷冻干燥后高的粗纤维、黄酮、三萜类化合物含量。三个采收期木枣果肉颜色均为绿白色，白熟期木枣质地相对偏硬，半红期和全红期没有显著（P>0.05）差异，真空冷冻干燥较好的保持了木枣原有的色泽品质和质构特性，而自然晾干和热风干燥则促使白熟期和半红期木枣果皮果肉均由绿转红，色差增大，硬度升高，接近甚至高于全红期木枣。由此可得，提前采收的白熟期和半红期木枣具备较好的加工利用特性，真空冷冻干燥为木枣高值化加工的首选干燥方法。研究结果为木枣提前采收加工利用提供了理论依据。

Quantitative assessment of bioactive compounds and the antioxidant activity of 15 jujube cultivars

In order to make full use of jujube resources and further explore the processing and utilization value of jujube fruit, the changes of jujube nutrition, color and quality indexes after natural drying, hot air drying and vacuum freeze-drying in different harvesting stages were compared and analyzed using mu-jujube fruit as the test material. The results showed that the contents of V_C, crude fiber, flavonoids and triterpenoids of white ripe dates were higher than those of semi-red dates, and those of semi-red dates were higher than those of all-red dates under the same drying methods. The contents of soluble sugars and polysaccharides of white ripe dates were significantly (P<0.05) lower than those of semi-red dates and the semi-red dates were significantly (P<0.05) lower than those all-red dates. Except for soluble sugars, all three harvesting stages of jujube had the highest content of functional nutrients after vacuum freeze-drying, but the content of crude fiber, flavonoids and triterpenoids after natural drying or hot air drying were higher at the white ripening stage and the semi-red stage than that of all-red stage of jujube fruit after vacuum freeze-drying. Flesh color of jujube during three harvest stages were green and white. The jujube texture at white ripe period was relatively hard, there was no significant difference between half red period and full red period (P>0.05). The original color, quality and texture of jujube were kept by vacuum freeze drying, while the flesh of white ripe period and half red stage jujube turned green to red, and the color difference and hardness increased after natural drying and hot air drying, which were close to or even higher than that of full red stage jujube. It could be concluded that the early harvested white and semi-red jujube fruit had better processing characteristics, and vacuum freeze-drying was the best drying method for high-value drying process. The results would provide a theoretical basis for early harvesting and processing of jujube fruit.