Cassava Pulp Hydrolysis under Microwave Irradiation with Oxalic Acid Catalyst for Ethanol Production


  • Euis Hermiati R&D Unit for Biomaterials, Indonesian Institute of Sciences (LIPI)
  • Shuntaro Tsubaki Oceanography Section, Science Research Center, Kochi University
  • Jun-ichi Azuma Graduate School of Engineering, Osaka University



activated carbon, cassava pulp, glucose, hydrolysis, microwave, oxalic acid, severity parameter.


Microwave irradiation is an alternative method of starch hydrolysis that offers a rapid process. The aim of this research was to improve microwave-assisted hydrolysis of cassava pulp by using oxalic acid as a catalyst. Suspension of cassava pulp in 0.5% oxalic acid (1 g/20 mL) was subjected to microwave irradiation at 140-230 C for 5 minutes, with 4 minutes of pre-heating. One gram of fractured activated carbon made of coconut shell was added into a number of suspensions that were subjected to the same conditions of microwave irradiation. The soluble fraction of the hydrolysates was analyzed for its total soluble solids, malto-oligomer distribution, glucose content, pH value, and formation of brown compounds. The effects of the combined severity parameter at a substrate concentration of 5-12.5% on the glucose yield were also evaluated. The highest glucose yield (78% of dry matter) was obtained after hydrolysis at 180 C without activated carbon addition. Heating above 180 C reduced the glucose yield and increased the pH and the formation of brown compounds. The use of activated carbon in microwave-assisted acid hydrolysis of cassava pulp reduced the glucose yield, but suppressed the formation of brown compounds. The highest glucose yield (70-80% of dry matter) was attained at a severity parameter of 1.3-1.5.


Li, P. & Zhu, M., A Consolidated Bio-processing of Ethanol from Cassava Pulp Accompanied by Hydrogen Production, Bioresource Technol., 102, pp. 10471-10479, 2011.

Sriroth, K., Chollakup, R., Chotineeranat, S., Piyachomkwan, K. & Otes, C.G., Processing of Cassava Waste for Improved Biomass Utilization, Bioresource Technol., 71, pp. 63-69, 2000.

Kunhi, A.A.M., Ghildyal, N.P., Lonsane, B.K., Ahmed, S.Y. & Natarajan, C.P., Studies on Production of Alcohol from Saccharified Waste Residue from Cassava Starch Processing Industries,Starch/Starke, 33, pp. 275-279, 1981.

Hermiati, E., Azuma, J., Mangunwidjaja, D., Sunarti, T.C., Suparno, O. & Prasetya, B., Hydrolysis of Carbohydrates in Cassava Pulp and Tapioca Flour under Microwave Irradiation, Indo. J. Chem., 11, pp. 238-245, 2011.

Hermiati, E., Azuma, J., Tsubaki, S., Mangunwidjaja, D., Sunarti, T.C., Suparno, O. & Prasetya, B., Improvement of Microwave-Assisted Acid Hydrolysis of Cassava Pulp and Tapioca Flour under Microwave Irradiation.Carbohyd. Polym., 87, pp. 939-942, 2012.

Ahmed, S.Y., Ghildyal, N.P., Kunhi, A.A.M. & Lonsane, B.K., Confectioner's Syrup from Tapioca Processing Waste, Starch/Starke, 35, pp. 430-432, 1983.

Srikanta, S., Jaleel, S.A., Ghildyal, N.P., Lonsane, B.K. & Karanth, N.G., Novel Technique for Saccharification of Cassava Fibrous Waste for Alcohol Production,Starch/Starke, 39, pp. 234-237, 1987.

Woiciechowski, A.L., Nitsche, S., Pandey, A. & Soccol, C.R., Acid and Enzymatic Hydrolysis to Recover Reducing Sugars from Cassava Bagasse: An Economic Study, Braz. Arch. Biol. Techn., 45(3), pp. 393-400, 2002.

Jaleel, S.A., Srikanta, S., Ghildyal, N.P. & Lonsane, B.K., Simultaneous Solid Phase Fermentation and Saccharification of Cassava Fibrous Residue for Production of Ethanol. Starch/Starke, 40, pp. 55-58, 1988.

Chotineeranat, S., Pradistsuwana, C., Siritheerasas, P. & Tantratian, S., Reducing Sugar Production from Cassava Pulp Using Enzymes and Ultra-filtration I: Enzymatic Hydrolation, J. Sci. Res. Chula. Univ.,29(2), pp. 119-128, 2004.

Kongkiattikajorn, J. & Yoonan, K., A Study of Optimal Conditions for Reducing Sugars Production from Cassava Peels by Diluted Acid and Enzymes,Kasetsart J. (Nat. Sci.), 38, pp. 29-35, 2004.

Srinorakutara, T., Kaewvimol, L. & Saengow, L., Approach of Cassava Waste Pretreatments for Fuel Ethanol Production in Thailand,J. Sci. Res. Chula. Univ., 31, pp. 77-84, 2006.

Rattanachomsri, U., Tanapongpipat, S., Eurwilaichitr, L. & Champreda, V., Simultaneous Non-Thermal Saccharification of Cassava Pulp by Multi-Enzyme Activity and Ethanol Fermentation by Candida Tropicalis, J. Biosci. Bioeng., 107, pp. 488-493, 2009.

Zhu, M., Li, P., Gong, X. & Wang, J., A Comparison of The Production of Ethanol Between Simultaneous Saccharification and Fermentation and Separate Hydrolysis and Fermentation Using Unpretreated Cassava Pulp and Enzyme Cocktail.Biosci. Biotech. Bioch., 76, pp. 671-678, 2012.

Virunanon, C., Ouephanit, C., Burapatana, V. & Chulalaksananukul, W., Cassava Pulp Enzymatic Hydrolysis Process as A Preliminary Step in Bio-alcohols Production From Waste Starchy Resources, J. Clean. Prod., 39, pp. 273-279, 2013.

Yamaji, K., Matsumura, Y., Ishitani, H., Yamada, K., Wyman, C.E. & Tolan, J.S., Production of Low-Cost Bioethanol to be A Rival to Fossil Fuel, New Energy and Industrial Technology Development Organization (NEDO),, 2006 (16 May 2008).

Yamaji, K., Yamamoto, H.&Nagatomi, Y., Evaluation of Ethanol Production from Cassava Pulp in Thailand with a Biomass Collection and Utilization Model, in Proceedings of COE Symposium on Advanced Electronics for Future Generations - Secure Life Electronics for Quality Life and Society, pp. 329-335, 2007.

Kosugi, A., Kondo, A., Ueda, M., Murata, Y., Vaithanomsat, P., Thanapase,W., Arai, T.& Mori, Y., Production of Ethanol from Cassava Pulp via Fermentation with A Surface Engineered Yeast Strain Displaying Glucoamylase,Renew. Energ., 34, pp. 1354-1358, 2009.

Nair, M.P.D., Padmaja, G. & Moorthy, S.N., Biodegradation of Cassava Starch Factory Residue Using a Combination of Cellulases, Xylanases and Hemicellulases, Biomass Bioenerg., 35, pp. 1211-1218, 2011.

Weerachanchai, P., Leong, S.S.J., Chang, M.W., Ching, C.B. & Lee, J.M., Improvement of Biomass Properties by Pretreatment with Ionic Liquids for Bioconversion Process, Bioresource Technol., 111, pp. 453-459, 2012.

Taherzadeh, M.J. & Karimi, K., Acid-Based Hydrolysis Processes for Ethanol from Lignocellulosic Materials: A Review, BioResources, 2(3), pp. 472-499, 2007.

Fontana, J.D., Mitchell, D.A., Molina, O.E., Gaitan, A., Bonfim, T.M.B., Adelmann, J., Grzybowski, A. & Passos, M., Starch Depolymerization with Diluted Phosphoric Acid and Application of The Hydrolysate in Astaxanthin Fermentation, Food Technol. Biotech., 46(3), pp. 305-310, 2008.

Matsumoto, A., Tsubaki, S., Sakamoto, M. & Azuma, J., A Novel Saccharification Method of Starch Using Microwave Irradiation with Addition of Activated Carbon,Bioresource Technol.,102, pp. 3985- 3988, 2011.

Chum, H.L., Johnson, D.K., Black, S.K. & Overend, R.P., Pretreatment-Catalyst Effects and The Combined Severity Parameter, Appl. Biochem. Biotech., 24/25, pp. 1-14, 1990.

Chum, H.L., Johnson, D.K. & Black, S.K., Organosolv Pretreatment of Enzymatic Hydrolysis of Poplars. 2. Catalyst Effects and The Combined Severity Parameter, Ind. Eng. Chem. Res., 29(2), pp. 156-162, 1990.

Teramoto, Y., Lee, S.H. & Endo, T., Pretreatment of Woody and Herbaceous Biomass for Enzymatic Saccharification Using Sulfuric Acid-Free Ethanol Cooking, Bioresource Technol., 99, pp. 8856-8863, 2008.

Hermiati, E., Mangunwidjaja, D., Sunarti, T.C., Suparno, O. & Prasetya, B., Microwave-Assisted Acid Hydrolysis of Starch Polymer in Cassava Pulp in The Presence of Activated Carbon, Procedia Chem., 4, pp. 238-244, 2012.

Warrand, J. & Janssen, H.G., Controlled Production of Oligosaccharides from Amylose by Acid-Hydrolysis under Microwave Treatment: Comparison with Conventional Heating, Carbohyd. Polym.,69, pp. 353-362, 2007.

Whistler, R.L. & Daniel, J.R., Carbohydrates, Food Chemistry, Fennema, O.R. (ed.), New York, Marcel Dekker, pp. 69-137, 1985.

Thongchul, N., Navankasattusas, S. & Yang, S.T., Production of Lactic Acid and Ethanol by Rhizopus oryzae Integrated with Cassava Pulp Hydrolysis.,Bioprocess Biosyst. Eng., 33, pp. 407-416, 2010.

Khan, A.R., Johnson, J.A. & Robinson, R.J., Degradation of Starch Polymers by Microwave Energy. Cereal Chem.,56(4), pp. 303-304, 1979.

Matsumoto, A., Tsubaki, S., Sakamoto, M. & Azuma, J., Oligosaccharides Adsorbed on Activated Charcoal Powder Escaped from Hydrolysis by Microwave Heating in Water,in Proceedings of Global Congress on Microwave Energy Applications, pp. 785-788, 2008.