DRYING CHARACTERISTICS AND QUALITY ANALYSIS OF HOT AIR-ASSISTED RADIO FREQUENCY AND HOT-AIR DRYING OF JUJUBE ( Zizyphus jujube Miller cv. Jinsixiaozao )

Abstract

Radio frequency (RF) drying is a rapid dehydration technique that reduces water activity and extends the shelf life of agricultural products. In this study, the drying characteristics of jujube during HARF and hot air (HA) were investigated, and quality analyses, such as color, vitamin C (VC) and total flavonoid content (TFC), of jujube were performed. The drying curves revealed that the drying time used to reduce the moisture content from 81.7 to 6.0% on a dry basis was 360 and 1320 min using HARF drying and hot air (HA) drying, respectively. The logarithmic model was the best to describe the HARF drying process with R 2 , RMSE and SSE values of 0.998, 0.00508 and 0.000306, respectively. Quality analysis demonstrated significant differences in color, VC content and total flavonoid content between the HARF and HA treatments during the drying process and storage periods (P > 0.5), and the HARF-dried jujube product performed much better than that dried by HA. Compared with HA drying, HARF drying showed a shorter drying time, higher drying efficiency and better product quality, indicating that HARF drying was a more promising drying method for jujube with acceptable product quality.

Hepatoprotective Effect of Dried Red Jujube Fruit Extract Against Acetaminophen-Induced Acute Hepatotoxicity

“…The product storage factors, such as temperature and duration, also have a significant role in the reduction of bioactive compound levels in jujube fruit extract. TPC and TFC levels decreased faster at higher product storage temperatures and longer duration of product storage [ 13 , 14 ].…”

Microstructure Analysis and Quality Evaluation of Jujube Slices Dried by Hot Air Combined with Radio Frequency Heat Treatment at Different Drying Stages

“…For example, the investigation of drying characteristics of inshell hazelnuts dried by combined radio frequency (RF) and hot air (HA), the results showed that when RF heating was applied during or before HA drying, energy efficiency, drying efficacy, and nut quality were enhanced, the anisidine content is higher than the HA ones [9]. As for the jujube, a recent study showed that compared with HA drying, HARF drying showed a shorter drying time, higher drying efficiency and better product quality, that is, higher vitamin C content, smaller color difference and higher total flavonoid content [10].…”