DETERMINATION OF DRYING PARAMETERS, ASCORBIC ACID CONTENTS AND COLOR CHARACTERISTICS OF NETTLE LEAVES DURING MICROWAVE-, AIR- AND COMBINED MICROWAVE-AIR-DRYING


Alibas İ.

JOURNAL OF FOOD PROCESS ENGINEERING, vol.33, no.2, pp.213-233, 2010 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 33 Issue: 2
  • Publication Date: 2010
  • Doi Number: 10.1111/j.1745-4530.2008.00268.x
  • Title of Journal : JOURNAL OF FOOD PROCESS ENGINEERING
  • Page Numbers: pp.213-233

Abstract

Nettle leaves (Urtica dioica L.), with a moisture of 4.41 (dry basis [d.b .]), were dried using three drying methods: microwave, air and combined microwave-air. Drying continued until leaf moisture decreased to 0.1 (d.b .). Three different microwave output powers, 160, 350 and 500 W, were used in the microwave-drying. Drying treatments in air-drying were 50, 75 and 100C, and 1 m/s fan speed. The combination drying, in which microwave- and air-drying were applied together, was nine different combination levels. Drying periods lasted for 6-14, 40-120 and 2-12 min for microwave-, air- and combined microwave-air-drying, respectively, depending on the drying level. Energy consumption was 0.07-0.10, 0.25-0.34 and 0.08-0.16 kWh, respectively. In this study, measured values were compared with the predicted values obtained from Page's semiempirical equation. Optimum drying period, color and energy consumption were obtained when microwave- and air-drying were applied simultaneously and the optimum combination level was 500-W microwave applications at 50C.