Thin Layer Drying Kinetics of Henna Leaves

Abstract

Henna leaves are well known for their cosmetic agent with anti-carcinogenic, anti-inflammatory, analgesic and antipyretic properties. To investigate the effect of different drying conditions on kinetics of henna leaves, the laboratory models of tunnel dryer was employed and the leaves were dried at 40, 45, 50, 55, 60 and 65°C. Drying of henna leaves prominently occurred in falling rate period and drying was faster at higher temperature. Twelve thin layer-drying models were fitted to the experimental moisture ratio data. Among the mathematical models investigated, the Midilli-Kucuk model satisfactorily described the drying behavior with highest r2 values. The effective moisture diffusivity (Deff) of basil leaves increased with the increase in drying air temperature. Effective moisture diffusivity of henna leaves ranged from 2.24•10-10 to 4.31•10-10 m2•s-1 and activation energy was 27.03 kJ•mol-1. The dried leaves were ground to make the powder and the powder had average particle size of 0.2069 mm with a fineness modulus of 1.3685.

Listovi kane su dobro poznati po svojim kozmetičkim agensima sa anti-kancerogenim, anti-inflamatornim, analgetskim i anti-piretičkim svojstvima. Laboratorijski modeli tunelske sušare su korišćeni za sušenje listova na 40, 45, 50, 55, 60 i 65°C i ispitivanje uticaja različitih uslova kinetiku sušenja listova kane. Period sušenja listova kane se skraćivao i sušenje je bilo brže pri višoj temperature. Dvanaest modela sušenja tankog sloja je poređeno sa eksperimentalnim podacima o odnosima vlage. Među matematičkim modelima koji su ispitivani, model Midilli-Kucuk je na zadovoljavajući način opisao ponašanje pri sušenju sa najvišim vrednostima r2. Efektivna difuzija vlage (Deff) listova povećala se sa povećanjem temperature vazduha za sušenje. Efektivna difuzija vlage listova kane iznosila je od 2.24•10-10 do 4.31•10-10 m2•s-1, a energija aktivacije 27.03 kJ•mol-1. Osušeni listovi su mleveni u prah sa prosečnim dimenzijama čestica od 0.2069 mm i modulom finoće 1.3685.