ISSN 2308-4057 (Print),
ISSN 2310-9599 (Online)

Coffee pulp pretreatment methods: A comparative analysis of hydrolysis efficiency

The Vietnamese food industry produces a lot of coffee pulp, which is a valuable and abundant source of agricultural by-products. It contains a lot of cellulose, which can be converted into bioethanol. However, coffee pulp needs an extensive pretreatment to reduce the amount of lignin and hemicellulose while retaining the initial cellulose composition. This study compared several pre-hydrolysis and pre-fermentation pretreatment methods which involved H2SO4, NaOH, microwaves, and white rot fungus Phanerochaete chrysosporium.
The hemicellulose dropped by 43.8% after the acidic pretreatment, by 47.1% after the alkaline pretreatment, and by 12.8% after the microbial pretreatment. The lignin contents dropped by 4.2, 76.6, and 50.2% after acidic, alkaline, and microbial pretreatment, respectively. The removal of hemicellulose and lignin in the coffee pulp was much more efficient when two or three of the pretreatment methods were combined. The microwave-assisted acid and alkaline pretreatment was the most efficient method: it removed 71.3% of hemicellulose and 79.2% of lignin. The combined method also had the highest amount of reducing sugars and glucose in hydrolysate. Additionally, concentrations of such yeast inhibitors as 5-hydroxymethyl-2-furaldehyde (HMF) and furfural were 2.11 and 3.37 g/L, respectively.
The acid pretreatment was effective only in removing hemicellulose while the alkaline pretreatment was effective in lignin removal; the fungal pretreatment had low results for both hemicellulose and lignin removals. Therefore, the combined pretreatment method was found optimal for coffee pulp.
Coffee pulp, hydrolysis, lignin, hemicellulose, reducing sugars, acidic pretreatment, alkaline pretreatment
  1. Sheng Y, Lam SS, Wu Y, Ge S, Wu J, Cai L, et al. Enzymatic conversion of pretreated lignocellulosic biomass: A review on influence of structural changes of lignin. Bioresource Technology. 2021;324.
  2. Coffee: World markets and trade. United States Department of Agriculture; 2020. 9 p.
  3. Phuong DV, Quoc LPT, Tan PV, Duy LND. Production of bioethanol from Robusta coffee pulp (Coffea robusta L.) in Vietnam. Foods and Raw Materials. 2019;7(1):10–17.
  4. Dadi D, Beyene A, Simoens K, Soares J, Demeke MM, Thevelein JM, et al. Valorization of coffee byproducts for bioethanol production using lignocellulosic yeast fermentation and pervaporation. International Journal of Environmental Science and Technology. 2018;15:821–832.
  5. Shankar K, Kulkarni NS, Jayalakshmi SK, Sreeramulu K. Saccharification of the pretreated husks of corn, peanut and coffee cherry by the lignocellulolytic enzymes secreted by Sphingobacterium sp. ksn for the production of bioethanol. Biomass and Bioenergy. 2019;127.
  6. Duarte A, Uribe JC, Sarache W, Calderón A. Economic, environmental, and social assessment of bioethanol production using multiple coffee crop residues. Energy. 2021;216.
  7. Solarte-Toro JC, Romero-García JM, Martínez-Patiño JC, Ruiz-Ramos E, Castro-Galiano E, Cardona-Alzate CA. Acid pretreatment of lignocellulosic biomass for energy vectors production: A review focused on operational conditions and techno-economic assessment for bioethanol production. Renewable and Sustainable Energy Reviews. 2019;107:587–601.
  8. Woiciechowski AL, Dalmas Neto CJ, de Souza Vandenberghe LP, de Carvalho Neto DP, Sydney ACN, Letti LAJ, et al. Lignocellulosic biomass: Acid and alkaline pretreatments and their effects on biomass recalcitrance – Conventional processing and recent advances. Bioresource Technology. 2020;304.
  9. Ziegler-Devin I, Chrusciel L, Brosse N. Steam explosion pretreatment of lignocellulosic biomass: A mini-review of theorical and experimental approaches. Frontiers in Chemistry. 2021;9.
  10. Hoang AT, Nižetić S, Ong HC, Mofijur M, Ahmed SF, Ashok B, et al. Insight into the recent advances of microwave pretreatment technologies for the conversion of lignocellulosic biomass into sustainable biofuel. Chemosphere. 2021;281.
  11. Scapini T, dos Santos MSN, Bonatto C, Wancura JHC, Mulinari J, Camargo AF, et al. Hydrothermal pretreatment of lignocellulosic biomass for hemicellulose recovery. Bioresource Technology. 2021;342.
  12. Mishra S, Singh PK, Dash S, Pattnaik R. Microbial pretreatment of lignocellulosic biomass for enhanced biomethanation and waste management. 3 Biotech. 2018;8.
  13. Wang W, Lee D-J. Lignocellulosic biomass pretreatment by deep eutectic solvents on lignin extraction and saccharification enhancement: A review. Bioresource Technology. 2021;339.
  14. Sahoo D, Ummalyma SB, Okram AK, Pandey A, Sankar M, Sukumaran RK. Effect of dilute acid pretreatment of wild rice grass (Zizania latifolia) from Loktak Lake for enzymatic hydrolysis. Bioresource Technology. 2018;253:252–255.
  15. Martínez-Patiño JC, Lu-Chau TA, Gullon B, Ruiz E, Romero I, Castro E, et al. Application of a combined fungal and diluted acid pretreatment on olive tree biomass. Industrial Crops and Products. 2018;121:10–17.
  16. Łukajtis R, Rybarczyk P, Kucharska K, Konopacka-Łyskawa D, Słupek E, Wychodnik K, et al. Optimization of saccharification conditions of lignocellulosic biomass under alkaline pre-treatment and enzymatic hydrolysis. Energies. 2018;11(4).
  17. Hassan SS, Williams GA, Jaiswal AK. Emerging technologies for the pretreatment of lignocellulosic biomass. Bioresource Technology. 2018;262:310–318.
  18. Sun Z, Mao Y, Liu S, Zhang H, Xu Y, Geng R, et al. Effect of pretreatment with Phanerochaete chrysosporium on physicochemical properties and pyrolysis behaviors of corn stover. Bioresource Technology. 2022;361.
  19. Miller GL. Use of dinitrosalicylic acid reagent for determination of reducing sugar. Analytical Chemistry. 1959;31(3):426-428.
  20. Sadasivam S, Manickam A. Biochemical Methods. New Delhi: New Age International (P) Ltd. Publishers; 1996. 272 p.
  21. van Soest PJ, Robertson JB, Lewis BA. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science. 1991;74(10):3583–3597.
  22. Ghose T. Measurement of cellulase activities. Pure and Applied Chemistry. 1987;59(2):257–268.
  23. Sun C, Liao Q, Xia A, Fu Q, Huang Y, Zhu X, et al. Degradation and transformation of furfural derivatives from hydrothermal pre-treated algae and lignocellulosic biomass during hydrogen fermentation. Renewable and Sustainable Energy Reviews. 2020;131.
  24. Agrawal R, Verma A, Singhania RR, Varjani S, Di Dong C, Patel AK. Current understanding of the inhibition factors and their mechanism of action for the lignocellulosic biomass hydrolysis. Bioresource Technology. 2021;332.
  25. Periyasamy S, Isabel JB, Kavitha S, Karthik V, Mohamed BA, Gizaw DG, et al. Recent advances in consolidated bioprocessing for conversion of lignocellulosic biomass into bioethanol – A review. Chemical Engineering Journal. 2022;453.
  26. Chen Z, Wan C. Ultrafast fractionation of lignocellulosic biomass by microwave-assisted deep eutectic solvent pretreatment. Bioresource Technology. 2018;250:532–537.
How to quote?
Phuong DV, Nguyen LT. Coffee pulp pretreatment methods: A comparative analysis of hydrolysis efficiency. Foods and Raw Materials. 2024;12(1):133–141.
About journal