Abstract

Coffee pulp is the first waste product obtained during the wet processing of coffee beans. Coffee pulp makes up nearly 40% of the total weight of the coffee cherry. Coffee pulp contains 25.88% of cellulose, 3.6% of hemicel- luloses, and 20.07% of lignin. Coffee pulp is considered as an ideal substrate of lignocellulose biomass for micro- bial fermentation to produce such value-added products as ethanol. In this study, we used alkaline pre-treatment of the coffee pulp with NaOH (0.2 g/g biomass) in a microwave system at 120°C during 20 min. This method gave the best results: 71.25% of cellulose remained, and 46.11% of hemicellulose and 76.63% of lignin were removed. After that, the pre-treated biomass was hydrolyzed by Viscozyme Cassava C (enzyme loading was 19.27 FPU/g) at 50°C for 72 hours. The results showed that the highest reducing sugars and glucose concentration after hydrolysis were 38.21 g/l and 30.36 g/l, respectively. Then, the hydrolysis solution was fermented by S. cerevisiae (3.108 cells/ml) at 30°C for 72 hours. The highest concentration of ethanol obtained was 11.28 g/l. The result illustrated that, available and non- edible as it is, coffee pulp could be a potential feedstock for bioethanol production in Vietnam.

Keywords

Bioethanol, coffee pulp, Coffea robusta, lignocellulose biomass, hydrolysis, pre-treatment

REFERENCES

1. Ribeiro Filho E., Paiva P.C.A., Barcelos A., et al. The effect of coffee hulls on the performance of Holstein-zebu steers during the growing period. Ciência e Agrotecnologia, 2000, vol. 24, pp. 225–232.
2. Leifa F., Pandey A., and Soccol C.R. Production of Flammulina velutipes on Coffee Husk and Coffee Spent-ground. Brazilian Archives of Biology and Technology, 2001, vol. 44, no. 2, pp. 205–212. DOI: https://doi.org/10.1590/S1516- 89132001000200015.
3. Shankaranand V. and Lonsane B. Coffee husk: an inexpensive substrate for production of citric acid by Aspergillus niger in a solid-state fermentation system. World Journal of Microbiology and Biotechnology, 1994, vol. 10, no. 2, pp. 165–168. DOI: https://doi.org/10.1007/bf00360879.
4. Franca A.S. and Oliveira L.S. Coffee processing solid wastes: current uses and future perspectives. Agricultural wastes, 2009, vol. 9, pp. 155–190.
5. Shenoy D., Pai A., Vikas R., et al. A study on bioethanol production from cashew apple pulp and coffee pulp waste. Biomass and Bioenergy, 2011, vol. 35, no. 10, pp. 4107–4111. DOI: https://doi.org/10.1016/j.biombioe.2011.05.016.
6. Oliveira L.S., Franca A.S., Camargos R.R., and Ferraz V.P. Coffee oil as a potential feedstock for biodiesel production. Bioresource Technology, 2008, vol. 99, no. 8, pp. 3244–3250. DOI: https://doi.org/10.1016/j.biortech.2007.05.074.
7. Saha B.C. and Cotta M.A. Fuel ethanol production from agricultural residues: current status and future prospects. Journal of Biotechnology, 2008, vol. 136, pp. S285–S286. DOI: https://doi.org/10.1016/j.jbiotec.2008.07.613.
8. Phuong D.V., Tan V.P., and Duy L.N.D. Determination of caffeine in coffee pulp (Coffea robusta) using UV- Visiblespectrophotometer. Vietnam Journal of Chemistry, 2017, vol. 55, pp. 86–91.
9. Ayesha S., Premakumari K., and Roukiya S. Antioxidant activity and estimation of total phenolic content of Muntingia calabura by colorimetry. International Journal of ChemTech Research, 2010, vol. 2, no. 1, pp. 205–208.
10. Lowry O.H., Rosebrough N.J., Farr A.L., and Randall R.J. Protein measurement with the Folin phenol reagent. Jour- nal of Biological Chemistry, 1951, vol. 193, pp. 265–275.
11. Carré M.H. and Haynes D. The estimation of pectin as calcium pectate and the application of this method to the de- termination of the soluble pectin in apples. Biochemical Journal, 1922, vol. 16, pp. 60. DOI: https://doi.org/10.1042/ bj0160060.
12. Dubois M., Gilles K.A., Hamilton J.K., Rebers P.T., and Smith F. Colorimetric method for determination of sug- ars and related substances. Analytical Chemistry, 1956, vol. 28, no. 3, pp. 350–356. DOI: https://doi.org/10.1021/ ac60111a017.
13. Miller G.L. Use of Dinitrosalicylic Acid Reagent for Determination of Reducing Sugar. Analytical Chemistry, 1959, vol. 31, no. 3, pp. 426–428. DOI: https://doi.org/10.1021/ac60147a030.
14. Le P.T.Q. and Pham M.H. The effects of ethephon on the ripening of carambola (Averrhoa carambola L.). Internatio- nal Food Research Journal, 2017, vol. 25, pp. 1497–1501.
15. Von Soest P. and Wine R. Use of detergents in the analysis of fibrous feed. Iv. Determination of plant cell-wall consti-tuent’s journal. Association of Analytical Chemistry, 1967, vol. 50, pp. 50–55.
16. Sayyad S.A.F., Chaudhari S., and Panda B. Quantitative determination of ethanol in arishta by using UV-visible spec- trophotometer. Pharmaceutical and Biological Evaluations, 2015, vol. 2, no. 5, pp. 204–207.
17. Chen Y., Sharma-Shivappa R.R., Keshwani D., and Chen C. Potential of Agricultural Residues and Hay for Bioe- thanol Production. Applied Biochemistry and Biotechnology, 2007, vol. 142, no. 3, pp. 276–290. DOI: https://doi. org/10.1007/s12010-007-0026-3.
18. Menezes E.G., do Carmo J.R., Alves J.G.L., et al. Optimization of alkaline pretreatment of coffee pulp for production of bioethanol. Biotechnology Progress, 2014, vol. 30, no. 2, pp. 451–462. DOI: https://doi.org/10.1002/btpr.1856.
19. Yang B. and Wyman C.E. Effect of xylan and lignin removal by batch and flowthrough pretreatment on the enzymatic digestibility of corn stover cellulose. Biotechnology and Bioengineering, 2004, vol. 86, no. 1, pp. 88–98. DOI: https:// doi.org/10.1002/bit.20043.
20. Thanonkeo P. The batch ethanol fermentation of jerusalem artichoke using Saccharomyces cerevisiae. KMITL Science and Technology Journal, 2007, vol. 7, no. 2, pp. 93–96.
21. Ballesteros M., Oliva J., Negro M., Manzanares P., and Ballesteros I. Ethanol from lignocellulosic materials by a simultaneous saccharification and fermentation process (SFS) with Kluyveromyces marxianus CECT 10875. Process Biochemistry, 2004, vol. 39, no. 12, pp. 1843–1848. DOI: https://doi.org/10.1016/j.procbio.2003.09.011.
22. Bonilla-Hermosa V.A., Duarte W.F., and Schwan R.F. Utilization of coffee by-products obtained from semi-washed process for production of value-added compounds. Bioresource technology, 2014, vol. 166, pp. 142–150. DOI: https:// doi.org/10.1016/j.biortech.2014.05.031.
23. Elias L. Chemical composition of coffee-berry by-products. In: Braham J.E. and Bressani R. (eds) Coffee pulp; com- position, technology, and utilization. Canada, Ottawa: Institute of Nutrition of Central America and Panama Publ., 1979. pp. 11–16.
24. Gurram R., Al-Shannag M., Knapp S., et al. Technical possibilities of bioethanol production from coffee pulp: a re- newable feedstock. Clean Technologies and Environmental Policy, 2016, vol. 18, no. 1, pp. 269–278. DOI: https:// doi.org/10.1007/s10098-015-1015-9.
25. Gouvea B., Torres C., Franca A., Oliveira L., and Oliveira E. Feasibility of ethanol production from coffee husks. Biotechnology letters, 2009, vol. 31, no. 9, pp. 1315–1319. DOI: https://doi.org/10.1007/s10529-009-0023-4.
26. Palonen H. Role of lignin in the enzymatic hydrolysis of lignocellulose. Espoo, Finland: VTT Publ., 2004. 84 p.
27. Zhang S., Maréchal F., Gassner M., et al. Process modeling and integration of fuel ethanol production from lignocel- lulosic biomass based on double acid hydrolysis. Energy & fuels, 2009, vol. 23, no. 3, pp. 1759–1765. DOI: https:// doi.org/10.1021/ef801027x.
28. Wiselogel A., Tyson S., and Johnson D. 6: Biomass feedstock resources and composition. In: Wyman C.E. (ed) Hand- book on Bioethanol: Production and Utilization. CRC Press Publ., 2018, pp. 105–118.
29. Goyal H.B., Saxena R.C., and Seal D. 3: Thermochemical conversion of biomass to liquids and gaseous fuels. In: Pandey A. (ed) Handbook of Plant-Based Biofuels. CRC Press Publ., 2008, pp. 29–43.
30. Gnansounou E. 5: Fuel ethanol. Current status and outlook. In: Pandey A. (ed) Handbook of Plant-Based Biofuels.CRC Press Publ., 2008, pp. 57–71.
31. Sun Y. and Cheng J. Hydrolysis of lignocellulosic materials for ethanol production: a review. Bioresource Technology, 2002, vol. 83, no. 1, pp. 1–11. DOI: https://doi.org/10.1016/s0960-8524(01)00212-7.
32. Wang Z. and Cheng J.J. Lime pretreatment of coastal bermudagrass for bioethanol production. Energy & Fuels, 2011, vol. 25, no. 4, pp. 1830–1836. DOI: https://doi.org/10.1021/ef2000932.
33. Kim S. and Holtzapple M.T. Lime pretreatment and enzymatic hydrolysis of corn stover. Bioresource Technology, 2005, vol. 96, no. 18, pp. 1994–2006. DOI: https://doi.org/10.1016/j.biortech.2005.01.014.
34. Fan L.T., Gharpuray M.M., and Lee Y.H. 2: Nature of cellulosic material. In: Fan L.T. (ed) Cellulose hydrolysis.Springer Publ, 1987, pp. 5–20.
35. Tarkow H. and Feist W. A. Mechanism for Improving Digestibility of Lignocellulosic Materials with Dilute Alkali and Liquid Ammonia. Advances in Chemistry Series, 1969, vol. 95, pp. 197–218. DOI: https://doi.org/10.1021/ba- 1969-0095.ch012.
36. Zhao X., Zhou Y., Zheng G., and Liu D. Microwave pretreatment of substrates for cellulase production by solid-state fermentation. Applied Biochemistry and Biotechnology, 2010, vol. 160, no. 5, pp. 1557–1571. DOI: https://doi. org/10.1007/s12010-009-8640-x.
37. Xu J., Chen H., Kádár Z., et al. Optimization of microwave pretreatment on wheat straw for ethanol production. Biomass and Bioenergy, 2011, vol. 35, no. 9, pp. 3859–3864. DOI: https://doi.org/10.1016/j.biombioe.2011.04.054.
38. McIntosh S. and Vancov T. Optimisation of dilute alkaline pretreatment for enzymatic saccharification of wheat straw. Biomass and Bioenergy, 2011, vol. 35, no. 7, pp. 3094–3103. DOI: https://doi.org/10.1016/j.biombioe.2011.04.018.
39. Martı́n C., Galbe M., Wahlbom C.F., Hahn-Hägerdal B., and Jönsson L.J. Ethanol production from enzymatic hydro- lysates of sugarcane bagasse using recombinant xylose-utilising Saccharomyces cerevisiae. Enzyme and Microbial Technology, 2002, vol. 31, no. 3, pp. 274–282. DOI: https://doi.org/10.1016/s0141-0229(02)00112-6.
40. Silverstein R.A., Chen Y., Sharma-Shivappa R.R., Boyette M.D., and Osborne J. A comparison of chemical pre- treatment methods for improving saccharification of cotton stalks. Bioresource Technology, 2007, vol. 98, no. 16, pp. 3000–3011. DOI: https://doi.org/10.1016/j.biortech.2006.10.022.
41. Ooshima H., Aso K., Harano Y., and Yamamoto T. Microwave treatment of cellulosic materials for their enzymatic hydrolysis. Biotechnology Letters, 1984, vol. 6, no. 5, pp. 289–294. DOI: https://doi.org/10.1007/bf00129056.
42. Lu X., Xi B., Zhang Y., and Angelidaki I. Microwave pretreatment of rape straw for bioethanol production: focus on energy efficiency. Bioresource Technology, 2011, vol. 102, no. 17, pp. 7937–7940. DOI: https://doi.org/10.1016/j. biortech.2011.06.065.
43. Chen M., Zhao J., and Xia L. Enzymatic hydrolysis of maize straw polysaccharides for the production of reducing sug- ars. Carbohydrate Polymers, 2008, vol. 71, no. 3, pp. 411–415. DOI: https://doi.org/10.1016/j.carbpol.2007.06.011.
44. Belkacemi K., Turcotte G., and Savoie P. Aqueous/steam-fractionated agricultural residues as substrates for etha- nol production. Industrial & Engineering Chemistry Research, 2002, vol. 41, no. 2, pp. 173–179. DOI: https://doi. org/10.1021/ie0102246.
45. Öhgren K., Bura R., Lesnicki G., Saddler J., and Zacchi G. A comparison between simultaneous saccharification and fermentation and separate hydrolysis and fermentation using steam-pretreated corn stover. Process Biochemistry, 2007, vol. 42, no. 5, pp. 834–839. DOI: https://doi.org/10.1016/j.procbio.2007.02.003.
46. Sahu O. Bioethanol production by coffee husk for rural area. Advanced Research Journal of Biochemistry and Bio- technology, 2014, vol. 1, pp. 1–5.
47. Kefale A., Redib M., and Asfaw A. Bioethanol Production and Optimization test from Agricultural Waste: The case of wet coffee processing waste (pulp). International Journal of Renewable Energy Research, 2012, vol. 2, pp. 446–450.
48. Yoswathana N., Phuriphipat P., Treyawutthiwat P., and Eshtiaghi M.N. Bioethanol production from rice straw. Energy Research Journal, 2010, vol. 1, no. 1, pp. 26–31. DOI: https://doi.org/10.3844/erjsp.2010.26.31.