Effect of vacuum microwave drying pretreatment on the production, characteristics, and quality of jujube powder

Abstract

The preparation of jujube powder is constrained by the phenomenon of sticky powder. Herein, vacuum microwave drying (MVD) pretreatment on the preparation of jujube powder was assessed using a one-factor combination response surface model and optimized the flow characteristics of the powder. Compared with hot air drying pretreatment, the optimized MVD-pretreated jujube powder reduced the tendency to aggregate, enhanced flowability, and increased powder indexes, including packing density, oil holding capacity, and the angle of repose, etc. Low-field nuclear magnetic resonance demonstrated that MVD pretreatment effectively removed most of the free water from the jujube powder. Additionally, relevant nutritional indicators were closer to those of the fresh sample. Electronic nose analysis indicated that the MVD jujube powder had a superior flavor profile. Thus, MVD pretreatment provides better retention of nutrients and flavor substances. These results provide a theoretical basis for the industrialized continuous production of high-quality jujube powder.