Microwave, Air and Combined Microwave-Air Drying of Grape Leaves (Vitis vinifera L.) and the Determination of Some Quality Parameters


Alibas I.

INTERNATIONAL JOURNAL OF FOOD ENGINEERING, vol.10, no.1, pp.69-88, 2014 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 10 Issue: 1
  • Publication Date: 2014
  • Doi Number: 10.1515/ijfe-2012-0037
  • Title of Journal : INTERNATIONAL JOURNAL OF FOOD ENGINEERING
  • Page Numbers: pp.69-88
  • Keywords: air drying, ascorbic acid, color, combined drying, grape leaves, microwave drying, LAYER, KINETICS, DEHYDRATION, APPLE, MODEL

Abstract

Grape leaves (Vitis vinifera L.) weighing 50 g (+/- 0.08) with a moisture of 4.08 kg((moisture)) kg((dry matter))(-1) (75.35% wb) were dried using three different drying methods: microwave, air and combined microwave- air. Drying continued until the leaf moisture decreased to 0.14 (+/- 0.01) kg((moisture)) kg((dry matter))(-1) (9.07% (+/- 0.20) wb). Drying periods lasted 5-11, 30-70 and 1.5-6 min for microwave, air and combined microwave-air drying, respectively, depending on the drying level. In this study, measured values of moisture were compared with values of predicted obtained from several thin-layer equations; the Alibas Model was found to have the best fit. The optimum drying period, color and ascorbic acid content were obtained by using the combined microwave-air drying method with the optimum combination of 500 W of microwave power at a temperature of 75 degrees C.