Selected chemical and physico-chemical properties of microwave-convective dried herbs

The purpose of the presented study was to describe kinetics of microwave-convection drying of basil (Ocimum basilicum), lovage (Levisticum officinale), mint (Mentha sp.), oregano (Origanum vulgare), parsley (Petroselinum crispum), and rocket (Eruca vesicaria) by means of different mathematical models, as well as to describe changes of polyphenols content, color and sorption properties after drying. The analyzed leaves were dried using microwaves power level of 300 W, in a temperature of 40 degrees C. Logistic model provided best fit to the experimental data. No significant differences in the drying kinetics could be discerned, while significant influence of herbs species on polyphenols contents, color and sorption properties was noted. The highest retention of phenolic compound, good resistance to color degradation and the highest water vapor adsorption concerned Apiaceae family (lovage, parsley), while worse properties in terms of these parameters were noted in Lamiaceae (basil, oregano, mint) and Brassicaceae (rocket). (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.