Effects of Three Drying Methods on Drying Quality of Mu-jujube at Different Harvest Periods

Abstract

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 VC, 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 (P0.05). 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.

Keywords

• mu-jujube
• harvest time
• dry
• quality