EFFECT OF MICROWAVE VACUUM DRYING ON PROTEIN AND CHLOROPHYLL CONTENTS OF BLIND NETTLE (Urtica urens L.)

Abstract

The effects of time, energy, and operational mode of microwave drying on the protein and chlorophyll contents of blind nettle extract were studied. Comparison of the modes showed that drying was faster in the normal than in the impulse mode. The kinetics of water loss followed a saturation-type behaviour. A virtual but significant increase in protein concentration was observed for the normal-mode, 300 W treatment. A constantly high energy input for a long time might damage proteins through the Maillard reaction. Normal-mode technique did destroy part of the chlorophyll content. It was concluded that the faster the drying, the more chlorophyll remained.