Apr 2, 2018 -
International Journal of Science Engineering and Technology Vol. 2, No. 1,2009 ISSN: 1985-3785 Available online at: www.ijset.org C 2008 ILRAM Publisher
Process Improvement of Pharmaceutical Grade Ethanol Production Using Sweet Sorghum lNajiah Nadir, lMaizirwan Mel, lMohd Ismail Abdul Karim. 2Rosli Mohd Yunus 'Blopro9)-«linkages. MeanwMe, amylopectin is a highly branched component of slllrch formed through chains of a-D-gIucopyranosyi residues linked together mainly by (1--+4) linkages but with 5-6% of (1-+6) bonds at the branch points. It is a branched poJysaccharide composed of hundreds of· short (l--+4}-a-glucan chains, which are inlerliukcd by (1-+6}-a-1inkagcs [10, II]. In most common types of cereal endosperm slllrches, the relative weight
2.3. Enzymes
percentages of amylose range between 18-33% and amylopectin range between 72-82010 amylopectin [10). Starchy grains and effluent generated from starch processing uiIits are the cheap feedstocks and could be used as potential raw materials for ethanol fermentation [12). The sweet sorghum starch hydrolysis may be regarded as a first and important step in sorghwn processing for bioethanol production [II). Enzymatic hydrolysis is essential for the production of glucose syrups from starch because of the specificity of enzymes allows the sugar syrups production with well-defined physical and chemical ploperties and the milder enzymatic hydrolysis results in few side reactions and less "browning" [2). Conventional process for production of bioethanol from starch basically involved a tbree-stage process liquefilction of starch by a-amylase, saa:barifie:ation of liquefied starch by glucoamylase and followed by fermentation - of sugar to ethanol using Saccharomyces cerevlslfU [I I, 12). The aim of this study was to investigate the liquefaction and saccharification processes of sweet sorghum by commercially available a-amylase and g1ucoamyla3e and ethanol fermentation of the obtained hydrolyzates by Saccharomyces cerevlslfU yeasts. The c:onditiOftS of starch hydrolysis such as the substrate and enzyme concentration and the tempenltlae and time required for the enzymatic action were optimized laking into account both the effects of hydrolysis and the ethanol- fermentation. Then, the most significant factors that affect the hydrolysis and fermentation processes have been quantified from the Design-Expert 6.0.8 of Taguchi Orthogonal Artay Design for the maximum ethanol
Both a-amylase from Bacillus subtiJls and glucoamylase from Aspergillus niger were obtained from local market. The activities of the two enzymes were 90% each. U. Hydrolysis The two litres B-Braun biorcactor was tilled with 200 g of sweet sorghwn and 900 ml of distilled water. Then, 0.05% (v/w) of a-amylase (from the amount of sorghwn) was added and the mixture was cooked at 80 ·C and 500 IpiIl for one hour. After one hour, the mixture was cooled down to 50·C and 0.05% (vlw) of glucoamylase was added and the mixture was left for two hoUl$ with 250 IpiIl agitation. Next, the solution was cooled down to 35 OC and the pH was adjusted to pH 5.
2.5. Fermentation
In the meantime, 0.5% (w/w) of urea and 0.05% (w/w) ofNPK (nitrogen, phosphorus, and potassiwn) were added to the bioreactor. After 10 min, the activated yeast solution was added to the two liters biorcactor. The mixture was mixed well and left for 8 hours without agitation. Then, the agitation was changed to SO IpiIl unlJ1 72 hOUl$ ofincubation. 1.6. Analysis Data was collected for every 8 hours. The concentration of glucose and ctbanol were determined by centrifuging at 5000 IpiIl for 30 minutes to remove cells. The supernatant was aDaIyzed by HPLC using an SUPELCOGEL C-610H column equipped with a refractive index detector. Separations were performed at 30 ·C, eluted at 0.5 mUmin using 0.1% H,PO,.
yield 1. Materials ud Methods
Sweet sorghwn grains were obtained from Indonesian supplier and blended into small size of approximately 100 jlIIl to enhance the hydrolysis
1.7. ExperimClltal design and optimization Taguchi Orthogonal Artay Design was used to improve the hydrolysis process for maximum bioethanol prodnction. Amount of substrate (A, gram),liqucfilction temperature (B, .C), liquefaction time (C. hour), amount of a-amylase (0, % (vlw», saccharification temperature (E. OC), saccharification time (F, hours), and amount of gIucoamylase (G, % (vlw» were chosen for the independent variables as shown in Table I. Ethanol concentration (y, % (v/v» was used as the dependent output variable.
process. 1.1. MIcroorganisms
Saccharomyces cerevlslfU yeast was obtained from local marIcet in chy form. For inoculum, 100 ml llf distilled water was heated to 40 ·C in a shake flask. After that, 0.5% (w/w) of Saccharomyces cerevlslae yeast was added into the warmed water to activate the yeast The mixture was left for 5-I0 min at lSOlpm.
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Table I. Independent variables in the experimental design Symbol
Variables
Coded levels Hi2h(2) 300 90 2 0.1 60 4 0.1
Low(]) A B C D E F
Amount of substrate, g ,oC Liquefilction Liquefilction time, h Amount of a-amylase, % (v/w) saccharification ,OC Sacchari1ication time, h Amount of g1ncoamylase, % (vlw)
200 80 I 0.05 50 2 0.05
G
regression model relating the ethanol (Y) with the independent variables, amount of substrate (A), Iiquefilction temperature (B), saccbaritication lempenlture (E) and saccharification time (F) is as follows: Y =-5.41975 + 0.030825A + 0.11170BO.048800E - 0.18325F (I)
3. Results and Discussion 3.1. Optimization of hydrolysis process
Eight expeliments were petfUimed using different combinations of the variables according to Taguchi OA Design. Using the resu1Is of the experiments, the Table 2. The observed and predicted resu1Is for ethanol yield
Rnn
A
