Microwave (MW)-related (MW-assisted or MW-enhanced) combination drying is a rapid dehydration technique that can be applied to specific foods, particularly to fruits and vegetables. Increasing concerns over product quality and production costs have motivated the researchers to investigate and the industry to adopt combination drying technologies. The advantages of MW-related combination drying include the following: shorter drying time, improved product quality, and flexibility in producing a wide variety of dried products. But current applications are limited to small categories of fruits and vegetables due to high start-up costs and relatively complicated technology as compared to conventional convection drying. MW-related combination drying takes advantages of conventional drying methods and microwave heating, leading to better processes than MW drying alone. This paper presents a comprehensive review of recent progresses in MW-related combined drying research and recommendations for future research to bridge the gap between laboratory research and industrial applications.

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Trends in microwave- related drying of fruits and vegetables

Microwave-assisted freeze drying (MFD) can be accomplished in two distinct ways: freeze drying assisted concurrently with microwave application (MFD-1) and freeze drying and assisted microwave/vacu...

Trends in Microwave-Assisted Freeze Drying of Foods

Summary

To obtain dehydrated bamboo shoot slices of high quality, a two-stage hybrid method of drying was tested to see if it could be cost-effective. While freeze-drying provides the best quality bamboo shoot it is a very expensive process. In this study, the drying techniques (a) hot airflow drying followed by vacuum freeze drying and (b) the reverse of the process (a) were examined. The quality of bamboo shoots dried by process (b) was found to be approximately equal to that of freeze-dried bamboo shoots but at a significantly lower cost. This paper reports results comparing the two processes in terms of energy consumption and the physico-chemical properties of the dried bamboo.

A two‐stage convective air and vacuum freeze‐drying technique for bamboo shoots

Summary To obtain dehydrated bamboo shoot slices of high quality, a two-stage hybrid method of drying was tested to see if it could be cost-effective. While freeze-drying provides the best quality bamboo shoot it is a very expensive process. In this study, the drying techniques (a) hot airflow drying followed by vacuum freeze drying and (b) the reverse of the process (a) were examined. The quality of bamboo shoots dried by process (b) was found to be approximately equal to that of freeze-dried bamboo shoots but at a significantly lower cost. This paper reports results comparing the two processes in terms of energy consumption and the physico-chemical properties of the dried bamboo.

Original article A two-stage convective air and vacuum freeze-drying technique for bamboo shoots

In this study, the fresh Moringa oleifera pods (Drumsticks) were dehydrated by microwave-assisted hot air drying (MAHD) and conventional hot air drying methods. The samples were dried at three different temperatures, viz. 50, 60, and 70°C, with and without the application of microwaves. Microwave power density of 1 W/g was used for the MAHD. The final moisture content was targeted as 13% wb. The drying curves and drying rate curves were plotted and compared. The kinetics of drying obtained experimentally were correlated with the Page equation. The constants K and N of the Page equation were determined to predict the drying kinetics for varying conditions. The quality attributes, namely, color, rehydration ratio, and volatile compounds, were analyzed and compared with that of the fresh Moringa pods. The volatile compounds were analyzed using z-Nose (an electronic nose; Electronic Sensor Technology, Newbury Park, CA) and bioactive molecules were analyzed using gas chromatography–mass spectrometry. The resul...

Effects of Microwave-Assisted Hot Air Drying and Conventional Hot Air Drying on the Drying Kinetics, Color, Rehydration, and Volatiles of Moringa oleifera

The definition and technological characteristic of combination drying were formulated in this workMeanwhile,this study introduced current research ad application for various combination drying methods inland and outlandFinally,existent problems and application prospects in the drying processing of Fruits fand Vegetables were discussed for the technology

Zhang Min

Papers

Research developments of combination drying technology for fruits and vegetables at home and abroad