FOOD SCIENCE ›› 2020, Vol. 41 ›› Issue (7): 117-123.doi: 10.7506/spkx1002-6630-20190403-045

• Food Engineering • Previous Articles     Next Articles

Effects of Radio Frequency Treatment on Short- and Medium-Wavelength Infrared Drying Kinetics and Quality Characteristics of Red Jujubes

WANG Kunhua, LI Jiamei, PENG Fei, LIU Yudi, MA Qi, LI Mei, XU Huaide   

  1. (College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China)
  • Online:2020-04-15 Published:2020-04-20

Abstract: Radio frequency (RF) technology was applied as a pretreatment for drying to shorten the drying process and improve the quality of dried red jujubes. Specifically, short- and medium-wavelength infrared drying was performed at 50, 60 or 70 ℃ to explore the drying kinetics and the quality characteristics of the dried red jujubes. In addition, the experimental results were fitted to eight common thin-layer drying models by nonlinear regression analysis and the optimum model was selected from these models. The results indicated that the drying time was shortened by 21.2%-29.3%; the effective diffusion coefficient of moisture was increased by 16.7%-49.6%; the activation energy of drying was reduced by 13.13% after RF treatment. In terms of correlation coefficient (R2), root-mean-square error (RMSE), and chi-square values (χ2), Weibull distribution was found to be the best model for describing and forecasting the short- and medium-wave infrared drying process following RF treatment of red jujubes. Comparatively, the color difference (ΔE) of dried jujubes after RF treatment decreased by 19.3%-31.4%, total phenol content increased by 14.9%-19.1%, and cyclic adenosine monophosphate content increased by 27.5%-31.9%. Compared with untreated jujubes, RF treated jujubes showed higher drying efficiency and better quality of dried products, indicating that RF is a promising pretreatment for dried jujube processing.

Key words: Ziziphus jujuba Mill., radio frequency treatment, short- and medium-wavelength infrared radiation drying, drying dynamics, quality, mathematical model

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