2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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hypertension) and promotes the sleepiness. Fortunately,
germination of mature paddy can enhance huge quantity
of GABA in rice kernel. Thus the GABA rice is a good
product for conferring a health benefit [2] and a food diet.
Additionally, Oh & Oh, 2004 [3] reported germinated
brown rice (GBR) extracted containing GABA inhibited
cancer cell proliferation. To investigate a novel method of
processing 11 germinated brown rice (GBR) varieties,
Norikoet.al, 2007 [4] processed grain of cultivars with a
large germ by soaking and gaseous treatment. After
soaking for 3 h and gaseous treatment for 21 h at 35
q
C,
the content of GABA in GBR was higher than that by the
conventional soaking method. Although the number of
microorganisms on the surface of the GBR increased
during soaking, steaming for 20 min and ethanol
discharge treatment for 3 min completely sterilized the
GBR and did not reduce the amount of GABA. However,
the geographical indication (GI) rice in Thailand was a
few variety and has a few research focusing on its
thermo-physical property and its moisture transfer during
drying such as convention solar drying, hot air drying and
so on. A GI is generally understood as a sign used on
goods that have a specific geographical origin and
possess qualities or a reputation that is due to that place
of origin [5].
Even some parameters can be comparatively related to
the other rice kernel in Thailand such as the safe moisture
content for long storage period below 16±1% dry-basis
[6], bulk density of rice kernel of 500-650 kg/m
3
depending on moisture content [7] etc.
Thus the main objectives of this study were to
investigate various thermo-physical properties in terms of
equilibrium moisture content (EMC), apparent density
(
U
), void fraction (
H
), specific heat capacity (c
p
) and
moisture diffusion coefficient (D). In addition, the drying
kinetic simulation was carried on under the conditions of
impingement drying and Infrared drying techniques.
III. M
ATERIAL AND
M
ETHOD
A. Sample Preparation
The fresh paddy (Sungyod) provided by the Rice
Research Institute at Phatthalung Province, Thailand. To
achieve uniform moisture content of paddy sample, the
fresh paddy was rewetted, well-mixed and kept in a cold
storage at temperature ranging of 4-6
q
C for a week.
Before doing experiment, the paddy was placed in
surrounding until the grain temperature was close to the
ambient temperature. The moisture content of the grain
sample was determined using AOAC 1995[8].
The paddy was washed in water to remove immature
grains and impurities. The paddy samples were soaked in
water at room temperature for 24-48 hours and soaked
water was drained and rinsed 4 hours per each. During
this soaking period rice kernel germination was evident
and let the paddy be GABA rice which endosperm
germination is around 1-2 mm length. Then, the paddies
were steamed at 95±5
q
C for 30 min and place in the
ambient for a period of 3 hours before drying [9].
B. Methodology
(a) Determination of equilibrium moisture content (EMC)
The five saturated salt solutions for achieving an
equilibrium moisture content stage used in this
experiments consists of KNO
3
, NaCl, Mg(NO
3
)
2
•6H
2
O,
MgCl
2
•6H
2
O and LiCl. These saturated salt solutions
provided relative humidity values of 10-90% relating to
their surrounding temperatures of 40-60
q
C. Then the
paddy samples put in stainless steel basket hanging on
each saturated salt solution were put in airtight vials. The
vials were placed in an incubator at temperatures of 40-
60
q
C to obtain final dry matter weight. The moisture
content was determined when the sample weight
remained unchanged after 3 consecutive weight
measurements (0.01 g). The samples were then taken and
weighed to determine the final moisture content (can be
so-called equilibrium moisture content, M
eq
) following
the AOAC method (AOAC, 1995).
The sample weight was evaluated by means of
triplication. Then, the isotherm models for predicting
EMC values were chosen to fitting the experimental data
are shown in Table 1.
TABLE I
MATHERMATICAL MODEL FOR PREDICT EQUILIBRIUM
MOISTURE CONTENT OF GABA SUNGYOD RICE [10]
The EMC was shown as a function of temperature and
relative humidity. The parameters of these models were
solved using the non-linear regression analysis. The
coefficient of determination (R
2
) and root mean square
error (RMSE) values were used as the primary criterion
for selecting the best equation to describe the
experimental data. The parameter was defined as shown
in Eq. (1) and (2) as below:
2 n
1i
iy
n
1i
2
iy n
2 n
1i
ix
n
1i
2
ix n
n
1i
iy
n
1i
ix
n
1i
iyix n
2
R
¦
¦
¦
¦
¦
¦
¦
(1)
Model name
Model equation
Oswin (1946)
B
RH)
(1
RH
A eqM
»
¼
º
«
¬
ª
Henderson (1952)
1/B
AT
RH)
ln(1
eqM
»¼
º
«¬
ª
Halsey (1948)
1/B]
C)
A/R(T -
ln(RH)
[
eqM
Modified Oswin
(1946)
C
RH)
(1
RH
BT)
(A eqM
»¼
º
«¬
ª
Modified GAB
(1985)
)B(RH)]
T
C
(
B(RH)
B(RH)][1
[1
)RH
T
C
AB(
eq
M
