`
Determination of Overall Mass Transfer Coefficient for 6-Gingerol and
6-Shagoal in Subcritical Water Extraction.
MD SARIP Mohd Sharizan
1, a
and MORAD Noor Azian
1,b
1
Centre of lipid Engineering Applied Research, Univerisiti Teknologi Malaysia, International
Campus, 54100, Kuala Lumpur, Malaysia.
a
mohd_sharizan@yahoo.com,
b
azian@ic.utm.my
Keywords: Subcritical Water Extraction, Mass Transfer Coefficient, 6-Gingerol, 6-Shagoal.
Abstract. Subcritical water extraction (SWE) is introduced in the extraction of ginger bioactive
compounds, namely 6-gingerol and 6-shagoal. The extraction mechanism is identified using mass
transfer coefficient model. The overall mass transfer coefficient, k or driving force for each
compound is measured through experimental determination. Compound identification and analysis
iss conducted using High Performance Liquid Chromatography (HPLC). The k value for 6-gingerol
and 6-shagoal under optimized condition (130
o
C, 3.5MPa) of 28:3 (ml:g) solvent to sample ratio are
0.02849 cm/min and 0.04873 cm/min, respectively.
Introduction
Subcritical water extraction (SWE) is a green extraction technique which involves the utilization
of water at its subcritical region. In this study, SWE mechanism is tested and measured for the
extraction of ginger’s main bioactive compound namely 6-gingerol and 6-shagoal. Mechanisms of
extraction of the bioactive compounds are explained through a mass transfer model. The model can
be expressed based on the mass balance for the process with the assumption that the amount
transferred is proportional to the concentration different and the interfacial area as illustrated in Eq.
1 and 2 [1].
Amount of
mass transferred
=k
Interfacial
area
Concentration
difference
V
dc
dt
= kA
c
sat − c
Where k is the overall mass transfer coefficient or driving force, V
L
is the bed volume, A
T
is the
surface area for the particles while c
1
is the species concentration in the bulk liquid and c
1
(sat) is
the initial species concentration at its core particle measured using ethanol extraction. The bed
volume and surface area for the particles is calculated using Eq. 3 and 4 respectively [2]. Equation 2
can be integrated into Eq. 5 for the experimental determination of overall mass transfer coefficient,
k.
!
=
6#
∅
%
&’
(
)
*
=
+
4
’
-
h
Where m = Particle mass, g.
Ø
s
= Particle sphericity, equivalent to 1.0.
ρ = Particles density, g/cm
3
D
p
= Particle diameter, cm.
D = Bed diameter, cm.
h = Bed height, cm.
− lnc
sat − c
= kAt
(1)
(2)
(3)
(4)
(5)
Advanced Materials Research Vols. 550-553 (2012) pp 1900-1903
Online available since 2012/Jul/26 at www.scientific.net
© (2012) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMR.550-553.1900
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
www.ttp.net. (ID: 161.139.152.237, Universiti Teknologi Malaysia UTM, Johor Bahru, Johor, Malaysia-03/09/13,08:26:28)