Analysis and technical optimization of processing condition for better quality of robusta coffee production


  • Usman Ahmad Department of Mechanical and Biosystem Engineering, Faculty of Engineering and Agricultural Technology, IPB University, IPB Dramaga Campus, Bogor, Indonesia.
  • Khalimatus Sa’diyah Postharvest Technology Magister Program, Graduates School, IPB University, IPB Dramaga Campus, Bogor, Indonesia.
  • Subramaniam Sathivel Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.



The wet processing of robusta coffee starts with harvesting coffee cherries, followed by sorting the cherries, pulping, fermentation, washing, drying, hard skin hulling, bean sorting, and packaging. Soaking fruit before pulping is an alternative for coffee farmers to delay the pulping process if time does not allow it. The fermentation process aims to remove mucus that is firmly attached to the hard skin. The addition of L. casei microbes can accelerate the process but affect the final taste. The study aimed to optimize the duration of soaking and fermentation processes for obtaining coffee beans with a minimum number of unpeeled beans, minimum partially black bean value, maximum taste quality, and to identify volatile components that play a role in forming the best steeping aroma after the coffee beans are roasted, ground and brewed.  Experiments and data analysis were carried out using the Response Surface Method design. The optimization results showed that 24 hours of soaking and 24 hours of fermentation were the optimum treatment based on the criteria for unpeeled beans response, partially black bean value, and total taste score with a desirability value of 0.721. The identified volatile compounds (43) include 9 aldehyde group compounds, 3 alcohols, 4 furans, 5 heterocyclic N, 6 ketones, 1 organic acid, 3 phenols, 10 pyrazines, and 2 thiols. The spicy and chocolaty aroma produced was also the highest among treatments, namely 8.98% and 7.74%. The treatment without soaking and fermentation had the highest percentages of caramelly and nutty areas, namely 23.14% and 21.35%, respectively.

Key words: Coffee beans; fermentation; soaking; technical optimization; volatile compound.


BRANDO, C. H. J.; BRANDO, M. F. Methods of coffee fermentation and drying. In: FLEET, SCHWAN, R. F. G. H. (ed), Cocoa and coffee fermentations. 1st ed. Boca Raton, Florida: CRC Press, p. 367-369, 2014.

BRESSANELLO, D. et al. Coffee aroma: Chemometric comparison of the chemical information provided by three different samplings combined with GC-MS to describe the sensory properties in cup. Food Chemistry, 214:218-226, 2017.

CAPORASO, N. et al. Variability of single bean coffee volatile compounds of Arabica and robusta roasted coffees analysed by SPME-GC-MS. Food Research International, 108: 628-640, 2018.

CHIN, S.; EYRES, G. T.; MARRIOTT, P. J. Identification of potent odourants in wine and brewed coffee using gas chromatography-olfactometry and comprehensive two-dimensional gas chromatography. Journal of Chromatography A, 1218 (42):7487-7498, 2011.

DIPPONG, T. et al. Analysis of volatile compounds, composition, and thermal behavior of coffee beans according to variety and roasting intensity. Foods, 11(9):3146, 2022.

DULSAT-SERRA, N.; QUINTANILLA-CASAS, B.; VICHI, S. Volatile thiols in coffee : A review on their formation, degradation, assessment, and influence on coffee sensory quality. Food Research International, 89:982-988, 2016.

FARAH, A.; DONANGELO, C. M. Phenolic compounds in coffee. Brazilian Journal of Plant Physiology, 18(1):23-36, 2006.

LÓPEZ-GALILEA, I. et al. Changes in headspace volatile concentrations of coffee brews caused by the roasting process and the brewing procedure. Journal of Agricultural and Food Chemistry, 54:8560-8566, 2006.

GIOVANNI, M. Response surface methodology and product optimization [1983]. Food Technology, 37(11):41-45, 2013.

HAALAND, D. P. Experimental design in biotechnology. New York: Marcel Dekker, Inc, 1989. Available at: Coffee Science, 18:e182080, 2023.

HURTADO-BENAVIDES, A.; SÁNCHEZ-CAMARGO, A. P. Study of the fatty acid profile and the aroma composition of oil obtained from roasted Colombian coffee beans by supercritical fluid extraction. The Journal of Supercritical Fluids, 113:44-52, 2016.

IAMANAKA, B. T. et al. Potential of volatile compounds produced by fungi to influence sensory quality of coffee beverage. Food Research International, 64:166-170, 2014.

JESZKA-SKOWRON, M.; ZGOŁA-GRZEŚKOWIAK, A.; GRZEŚKOWIAK, T. Analytical methods applied for the characterization and the determination of bioactive compounds in coffee. European Food Research and Technology, 240:19-31, 2015.

KIM, Y.; GIOVANNUCCI, E. Cofee consumption and all‑cause and cause‑specifc mortality: A meta‑analysis by potential modifers. European Journal of Epidemiology, 34:731-752, 2019.

LIU, C. et al. Modifying Robusta coffee aroma by green bean chemical pre-treatment. Food Chemistry, 272:251-257, 2019.

MONTGOMERY, D. C. Design and analysis of experiments eighth edition. 8th ed. Hoboken: John Wiley & Sons, Inc, 2012. 480p.

NIELSEN, S. S. Food analysis laboratory manual. 2th ed. USA: Springer Science and Business Media, 2016. 150p.

PANCANINGTYAS, S.; SANTOSO, T. I.; SUDARSIANTO. Study of cocoa seed growth through method immersion. Journal Pelita Perkebunan, 3(30):190-197, 2014.

PURNAMAYANTI, N. P. A.; GUNADNYA, I. B. T.; ARDA, G. Pengaruh suhu dan lama penyangraian terhadap karakteristik fisik dan mutu sensori kopi arabika (Coffee arabica L). Jurnal Biosistem dan Teknik Pertanian (BETA), 5(2):39-48, 2017.

PEREIRA, G. V. et al. Potential of lactic acid bacteria to improve the fermentation and quality of coffee during onfarm processing. International Journal of Food Science and Technology, 51(7):1689-1695, 2016.

POOLE, R. Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ, 359:j5024, 2017.

SA’DIYAH, K. et al. Pengaruh lama perendaman buah dan fermentasi terhadap warna kulit tanduk dan citarasa kopi robusta. Jurnal Tandaman Industri dan Penyegar, 6(1):33-40, 2019.

SARINANA, P. B. Y.; TRINIDAD, S. S. Chemistry and biotransformation of coffee by-product to biofuels. 2017.

SENANAYAKE S. P. J. N.; SHAHIDI, F. Lipase-catalyzed incorporation of docosahexaenoic acid (DHA) into borage

oil: optimization using response surface methodology. Food Chemistry, 77(1):115-123, 2002.

SHIBAMOTO, T. Volatile chemicals from thermal degradation of less volatile coffee components. Coffee in Health and Disease Prevention, 129-135, 2015.

SPECIALTY COFFEE ASSOCIATION OF AMERICA - SCA. SCAA protocols | cupping specialty coffee. 2015.

Available in: Acess in: April 12, 2023.

SUNARHARUM, W. B.; WILLIAMS, D. J.; SMYTH, H. E. Complexity of coffee flavor: A compositional and sensory

perspective. Food Research International, 62:315-325, 2014.

TÉLLEZ-LUIS, S. J. et al. Optimization of lactic acid production by lactobacillus delbrueckii through response surface methodology. Journal of Food Science, 68(4):1454-1458, 2003.

TOCI, A. T.; BOLDRIN, M. V. Z. Compounds. Natural and Artificial Flavoring Agents and Food Dyes. Elsevier Inc, 2018.

TORRES-COLLADO, L. et al. Coffee consumption and mortality from all causes of death, cardiovascular disease and cancer in an elderly Spanish population. European Journal of Nutrition, 58:2439-2448, 2019.

WAHYUDI, T.; PUJIYANTO; MISNAWI. Kopi: Sejarah, proses produksi, pengolahan, produk hilir, dan sistem kemitraan. Yogyakarta: Gajah Mada University Press, 2016. 890p.

WARLE, B. M. et al. Effect of germination on nutritional quality of soybean (Glycine Max). IOSR Journal of Enviromental Science, Toxicology, and Food Technology, 9(4):13-16, 2015.

YUSIANTO; WIDYOTOMO, S. Mutu dan citarasa Kopi Arabika hasil beberapa perlakuan fermentasi: suhu, jenis wadah, dan penambahan agens fermentasi. Pelita Perkebunan, 29(3):220-239, 2013.




How to Cite

AHMAD, U. .; SA’DIYAH, K. .; SATHIVEL, S. Analysis and technical optimization of processing condition for better quality of robusta coffee production. Coffee Science - ISSN 1984-3909, [S. l.], v. 18, p. e182080, 2023. DOI: 10.25186/.v18i.2080. Disponível em: Acesso em: 12 apr. 2024.