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The 5th PSU-UNS International Conference on Engineering and
Technology (ICET-2011), Phuket, May 2-3, 2011 Prince of Songkla University, Faculty of Engineering
Hat Yai, Songkhla, Thailand 90112
Abstract: Ethanol production from the weak skin of jelly
seeds of Palmyra Palm using Loog-Pang Kao Mhark
(Rice Cake starter) was investigated in this work. The
seed skin was crushed and boiled in a pretreatment step
to study the influence of: pretreatment temperature of 75
– 90 °C, pretreatment times of 15 – 60 min. Then ethanol
fermentation of the boiled seed skin was carried out to
study the influence of: fermentation times of 1 – 9 days
and Loog-Pang amount of 2 – 5%wt. The optimum
condition for the batch production that operated in 250
ml air-locked flasks was boiled at 80 ºC for 45 min in
pretreatment step, 5%wt of Loog-Pang for 7 days with
initial pH 5.5 at a room temperature. Under this
condition, it could provide 9.6%v/v purify of ethanol
product.
Key Words: Palmyra palm / Ethanol /Loog-Pang
1. INTRODUCTION
Ethanol (or bio-fuel) is defined as the ethyl alcohol
made from biomass (agricultural products and waste).
This renewable source is as efficient as petroleum fuel. It
releases less pollution into the air than the petroleum,
especially SO2. Using fuel from the plants is definitely a
way to preserve the environment by helping to reduce the
greenhouse effect as CO2 and NOX [1]. Thailand is one
of the countries that have a large quantity of fuel imports.
The alternative energy source, especially from
agricultural residue, will both increase farming incomes
and decrease our currency loss to foreign countries.
Ethanol can be used directly as fuel or blended with
benzene and diesel, and used as additive to gasoline
instead of methyl tertiary butyl ether (MTBE) [2].
Chemical and biological technology can be used for
producing ethanol. For the biological production, raw
materials can be divided into 3 major types: (1) sugar-
sugarcane and molasses, (2) starch-potato and rice, and
(3) fiber-wood and fruit skin [3]. The research of ethanol
production is focused on reducing production costs and
increasing energy efficiency of plant process.
Loog-Pang is a microorganism source (Yeast). It is
isolated and characterized by its morphological, genetic,
physiological and fermentation properties. It is a
traditional starter culture of alcoholic production for food
and drink industries [4]. Moreover, Loog-Pang can be
used to produce ethanol. The ethanol production from
Cassava starch was studied by using yeasts isolated from
Loog-Pang. The optimum condition was 5% (w/v)
cassava starch, 3% Saccharomycopsis sp. YCY1 at 37 ºC
with 100 rpm shaking rate. It could provide 5.72 g/l
ethanol product [5]. The ethanol fermentation of Sato for
14 days gave 11.58% and 10.66% purity of ethanol
products by using the pure culture microorganism,
Saccharomyces cereviceae TISTR 5049, and yeast cake,
respectively [6]. The ethanol production from shredded
cassava was carried out with 8 g. of Chinese yeast cake
and fermentation time of 31 days. The obtained highest
ethanol was 9.32% (v/v) [7]. The studying of ethanol
production from Cassava starch by using the selected
fungi from Tan-Koji (Loog-Pang) and Saccaromycetes
cereviseae were carried out with 6% Cassava starch. The
highest ethanol product content was achieved at 14.36 g/l
after 24 h of saccharification process (SFF) [8].
The main purpose of this work is to investigate the
possibility of ethanol production from the weak skin of
edible jelly seeds of Palmyra Palm (agricultural waste)
and to find the optimum condition for the production
using Loog-Pang Kao Mhark.
2. MATERIAL AND METHOD
2.1. Materials
The weak skin of edible jelly seeds of Palmyra palm
was obtained from agriculturist group that transforms the
Palmyra Palm product in Sathing Phra, Songkhla
province. The seed skin composition is given in table 1.
Loog-Pang was bought from a local market in
Narathiwat province, Thailand.
Ethanol production from the weak skin of
jelly seeds of Palmyra Palm by Loog-Pang
Asma Mardla1*, Sininart Chongkhong
1, Pakamas Chetpattananondh
1
1Prince of Songkla University, Faculty of Engineering, Thailand
*Authors to correspondence should be addressed via email: [email protected]
43
Table 1.The composition of the weak skin of edible jelly
seeds of Palmyra Palm.
Component Palmyra palm
Protein 1.47%
Crude Fat 0.15%
Moisture 92.78%
Ash 0.52%
Crude Fiber 0.44%
Total Carbohydrate 5.08%
energy 27.55 kcal
2.2. Pretreatment
The seed skin was crushed to be 1 mm particle size
and it was boiled for the physical pretreatments.
Operating parameters of the pretreatments were included
the boiling time in the range of 15 – 60 min and
temperatures in the range of 75 – 90°C with a water to
the seed skin ratio of 60%wt. Then it was cooled down
until it reached at room temperature.
2.3. Fermentation
The ethanol fermentation was carried out in 250 ml
air-locked flasks. The pretreated seed skin was poured
into the flasks following by Loog-Pang powder and
nitrogen gas for helping to scavenge the air or oxygen in
the flasks. The ethanol fermentation should be the
process without oxygen. The studied operating
parameters were the quantity of Loog-Pang in the range
of 2 – 5 %wt and fermentation times in the range of 1 – 9
days under a room temperature with an initial pH 5.5.
The fermented products were passed into a fabric filter to
separate a solid phase. Then a liquid phase was
centrifuged at 5000 rpm for 15 min to obtain the clear
liquid product before ethanol content analysis by a
refractometer.
2.4 Analytical Methods
Reducing sugar was measured by DNS
(Dinitrosalicylic Acid) Method using a double beam UV-
Vis Spectrophotometer by UV-Visible ChemStation
Software (Model: HP 8453) [9].
A standard curve of glucose solution (reducing sugar)
was prepared. One gram of the pure glucose was
dissolved in distilled water to obtain the 100 ml solution.
This stock solution (10.0 g/l) was used to make seven
appropriate glucose dilutions from 0.5 – 10.0 g/l that was
added DNS reagent into each tube at 1:1 volume ratio.
The blank solution was prepared similarly to stock
solution by using distilled water. The solutions in the
tubes were boiled at 85 °C for 30 min. Then they were
cooled until reach to a room temperature and diluted to
10.0 ml with distilled water. The transmittance value was
measured at 570 nm on a spectrophotometer.
Ethanol content was determined by the Refractometer
(ATAGO-Japan, model DR-A1 Digital ABBE). It can
read the ethanol content value by eye measurement. A
standard curve of ethanol in distilled water solution was
prepared with difference eight appropriate ethanol
solutions (0 – 45 %v/v).
3. RESULTS AND DISCUSSION
3.1 Standard curves
The standard curve of reducing sugar was shown in
Fig. 1.
Fig. 1. The standard curve of reducing sugar.
The standard curve of ethanol solution was shown in
Fig. 2.
Fig. 2. The standard curve of ethanol concentration.
3.2 Pretreatment
The partial components of the thermal pretreated
products as fiber and carbohydrate are transformed into
the sugars (smaller molecules). They can be assayed in a
term of glucose (reducing sugar).
3.2.1 Effect of boiling time
Fig. 3 shows the effect of boiling time on reducing
sugar content at a boiling temperature of 85°C. It can be
seen that the boiling time at 45 min and 60 min gives the
optimum reducing sugar amount. Therefore, the boiling
time for 45 min was enough to break down the starch
44
molecule into fermentable sugars for economic reason.
Moreover, it was found that a short-time of boiling was
not enough to reduce the size of molecule in the weak
skin reasonably.
Fig. 3. The effect of boiling time on reducing sugar
content.
3.2.2 Effect of boiling temperature
Fig. 4. The effect of boiling temperature on reducing
sugar content.
Fig. 4 shows the effect of boiling temperature on
reducing sugar content for a boiling time of 45 min. The
suitable boiling temperature was 80°C that molecular
structure was readily break down into fermentable
sugars.
The pretreated product was a higher viscosity
because the pretreatment process could change the
molecule structure of carbohydrate to be an active
molecule that was easier to be hydrolyzed. This process
could be called gelatinization.
The results (Fig. 3 and 4) show that the optimum
gelatinization condition was 80°C for 45 min.
3.3 Fermentation
3.3.1 Effect of Loog-Pang amount
Fig. 5 shows the effect of Loog-Pang amount on
ethanol content. For fermentation time of 7 days, the
rapid formation of ethanol was observed when Loog-
Pang amount was higher (2-5%). However, the
maximum ethanol content could be obtained by using
5%wt of Loog-Pang.
Fig. 5. The effect of Loog-Pang amount on ethanol
content.
3.3.2 Effect of fermentation time
It can be seen in Fig. 6 that for using 5%wt Loog-
pang, the ethanol conversion was raised when the
fermentation time was increased. The fermentation time
of 7 days was suitable for this process.
Fig. 6. The effect of fermentation time on ethanol
content.
4. CONCLUSION
The ethanol production from the seed skin of Palmyra
Palm by using microorganisms from Loog-Pang Kao
Mhark could provide 9.6%v/v ethanol product. The
optimum condition was 5%wt Loog-Pang amount for 7
days with pH-5.5 at a room temperature. The ethanol
products could be purified by a distillation or
evaporation.
5. ACKNOWLEDGEMENTS
The author gratefully acknowledges the financial
support from the Graduate School of Prince of Songkla
University.
45
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[6] W. Kheowrod, “Comparative study on the
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[7] P.Dumrongmanee, “Comparison of the amounts of
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46