Figure 1.2: The basics compound of cellulose is cellubiose, disaccharides of two β- 1-4 bonded glucoses 2.2.2 Hemicelluloses Hemicelluloses are heterogeneous polymers of pentoses (xylose, arabinose), hexoses (mannose, glucose, galactose) and sugar acids. In hardwood hemicelluloses mostly contains xylan, whereas softwood hemicelluloses contains mostly glucomannans. Xylan of many plant materials are heteropolysaccharides with homopolymeric backbone chains of 1,4-linked β-D-xylopyranose units. The monosaccharides released upon hemicellulose hydrolysis include a large fraction of pentoses (Gunda et al., 1970). In several plants the majority of hemicelluloses is xylan which can be hydrolyzed into xylose. Particularly the hemicellulose of hardwood is rich in xylan. Consequently it is possible to obtain xylan and xylose as by-products from cellulose industry using hardwood (Gunda et al., 1970). Figure 1.3 the structure of xylan and enzymes cleavage site. The complex structure of xylan needs different enzymes to complete its hydrolysis. The main enzyme that randomly hydrolysis the main chain of xylan to produce mixture xylooligosaccharides named as endoxylanase and β-xylosidase will liberate xylose from short oligosaccharides. Moreover, the sides groups presents in xylan are liberated
In order to improve this research method and results to a better concentration of glucose, it can be carried out in various modifications on these parameters. The concentration of glucose using the method of enzymatic hydrolysis can also be done using the method of acid hydrolysis which is cheaper in terms of the cost of raw material. Besides using only single enzyme, the concentration of glucose can be increased by mixing the three commercialized enzymes (cellulose, glucoamylase and α-amylase). There are also differences when using immobilize enzyme and free enzyme in concentration of glucose which can be studied to compare the concentration between the two types of enzymes. The concentration of glucose was analyzing using DNS reagent. But for future studies, analyzing the samples using High Performance Liquid Chromatography (HPLC) can gives more accurate concentration of glucose. In this study, the substrate used is cassava residue. In future, to study the concentration of substrate will give the significant in concentration of glucose. Moreover, there are more substrate other than cassava residue that are also capable of producing sugar such as Cotton Stalk, Corn Stover, Wheat Straw, Tobacco Stalk and Palm Oil Empty Fruit Bunch. This research can also be done by varying the agitation rate and the reaction temperature incubating. The pH of the buffer may give effect on the productions. Therefore, this can also be study by varying the pH of buffer. In addition, other kind of buffer can also be used such as Potassium Phosphate and Ampso. REFERENCES
APPENDIX A MATERIAL AND METHODS Appendix A1 Preparation mixture of Sodium Hydroxide (NaOH), (2000 mL) and Citric Acid (C6H8O7), (1000 mL) as Buffer Preparation of Sodium Hydroxide (NaOH), (2000 mL) Molecular weight of Sodium Hydroxide, NaOH = 40 g/mol Prepare volume of 10.8 mL from 0.1 M Sodium Hydroxide (NaOH) solution Then, 10.8 mL Sodium Hydroxide ( NaOH) was diluted with 1000 mL distilled water in volumetric flask. Preparation of Citric Acid (C6H8O7) , (1000 mL) Molecular weight of Sodium Hydroxide, NaOH = 192.14 g/mol Prepare mass of 19.214 g from 0.1 M on Citric Acid (C6H8O7) Therefore, 19.2 g of Citric acid (C6H8O7) was mixed into 1000 mL distilled water. Preparation of buffer Then, add some drop of Sodium Hydroxide, (NaOH) and Citric Acid (C6H8O7) into the mixture to achieve the value of pH needed.