Study on the Effect of Vacuum Microwave Drying on Quality of Okra

Abstract

The purpose of this paper is to investigate the impact of vacuum microwave drying on the quality of okra. The curves of colour, fracture resistance, rehydration ratio and the content of vitaminC were obtained at various drying times, vacuum degrees and microwave powers. Results showed that an increase in drying time and microwave power resulted in serious colour change when compare the dry product to fresh okra. However, the higher the vacuum, the slighter the colour changed. The fracture resistance decreased and the brittleness was good when drying time was increased to high level of 14min and 16min. Increasing vacuum degree also made fracture resistance decreased; rehydration ratio increased with the time and microwave power increased, but decreased if the time exceeds 14min. The rehydration ratio of okra is also affected by the vacuum degree, increasing which led the rehydration ratio increased significantly at the beginning of drying and then slowly; the greater the drying time and microwave power, the more lost of vitaminC, however, higher vacuum degree was found to be beneficial to save the vitaminC.