Effect of demucilagination and soaking in water with organic acids on the microbial, chemical, and sensory characteristics of coffee (Coffea arabica)





There are divided opinions regarding sensory quality of mechanically demucilaginated (MD) coffee versus coffee that has undergone conventional fermentation (biological demucilagination). Fermenting and washing (wet process) requires high amounts of water that has contaminating effects upon its completion. Studies indicate that MD with soaking in organic acids could develop similar sensory quality to wet processed coffee. Organic acids are bioactive compounds that are naturally produced during conventional fermentation, which is why coffee has unique characteristics in the final cup profile. This study was conducted to assess the effects of soaking with organic acids (citric, ascorbic, and acetic) on the microbial, chemical, and sensory attributes of MD coffee. A Completely Randomized Design (CRD) was used, with a factorial arrangement (2×4+2) for a total of 10 treatments. The treatments were two soaking times (24 and 48 hours) and four soaking solutions (citric, ascorbic, acetic acid and water) in coffee with mechanical demucilagination, one treatment with mechanical demucilagination and one with fermentation and washing, both without soaking or acids. Microbiological counts of fungi, yeasts, and lactic acid bacteria (LAB) were carried out before and after soaking. Sensory characteristics were evaluated through cupping and chemical content and properties were studied by liquid chromatography and spectrophotometry. Microbial population demonstrated normal succession throughout the experiment with LAB been the most prevalent family during MD and fermentation. Soaking coffee in acid solutions maintained overall cupping scores with different attributes being detected by panelists. Phenolic compounds, caffeine and chlorogenic acids increased in soaked samples (acetic acid) but were similar to the control (fermentation). Flavonoid content ranged from 22 to 35 mg EC/g and was higher in samples soaked in acids compared to the
controls. Green coffee extracts in general showed antioxidant activities greater than 80.9% comparable to other studies. Soaking time did not improve the quality characteristics of the coffee, but the type of acid used was able to modify the content and proportion of various families of chlorogenic acids in green coffee and total polyphenols, while maintaining sensory properties in comparison to fermented coffee

Key words: Acid solution; bioactive compounds; coffee extract; wet milling.


ABUBAKAR, Y. et al. Effect of varieties and processing practices on the physical and sensory characteristics of Gayo Arabica specialty coffee. IOP Conference Series: Materials Science and Engineering, 523:012027, 2019.

AYOKA, T. O. et al. Antioxidants for the prevention and treatment of non-communicable diseases. Journal of Exploratory Research in Pharmacology, 7(3):178-188, 2022.

BENÍTEZ-ESTRADA, A. et al. Determinación de la capacidad antioxidante total de alimentos y plasma humano por fotoquimioluminiscencia: Correlación con ensayos fluorométricos (ORAC) y espectrofotométricos (FRAP). TIP Revista Especializada en Ciencias Químico-Biológicas, 23:1-9, 2020.

BEROVIC, M.; LEGISA, M. Citric acid production. Biotechnology Annual Review, 13:303-343, 2007.

BORGHESI, D. C. et al. Biodegradation study of a novel poly-caprolactone-coffee husk composite film. Materials Research, 19(4):752-758, 2016.

BOZZOLA, M. et al. The coffee guide. (4th Edition). International Trade Centre, Geneva, Switzerland. 2021. 328p.

BYTOF, G. et al. Transient occurrence of seed germination processes during coffee post-harvest treatment. Annals of Botany, 100(1):61-66, 2007.

CRAIG, A. P. et al. Performance review of a fast HPLC-UV method for the quantification of chlorogenic acids in green coffee bean extracts. Talanta, 154:481-485, 2016.

DE MELO-PEREIRA, G. V. et al. Microbial ecology and starter culture technology in coffee processing. Critical Reviews in Food Science and Nutrition, 57(13):2775-2788, 2017.

ELHALIS, H. et al. The crucial role of yeasts in the wet fermentation of coffee beans and quality. International Journal of Food Microbiology, 333:108796, 2020.

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

FARAH, A.; LIMA, J. P. de. Consumption of chlorogenic acids through coffee and health implications. Beverages, 5(1):11, 2019.

FERRUZZI, M. G. The influence of beverage composition on delivery of phenolic compounds from coffee and tea. Physiology & Behavior, 100(1):33-41, 2010.

FIGUEROA CAMPOS, G. A. et al. Comparison of batch and continuous wet-processing of coffee: Changes in the main compounds in beans, by-products and wastewater. Foods, 9(8):1135, 2020.

GAENZLE, M. G. Lactic metabolism revisited: Metabolism of lactic acid bacteria in food fermentations and food spoilage. Current Opinion in Food Science, 2:106-117, 2015.

GARCÍA-MIER, L. et al. Agriculture and bioactives: Achieving both crop yield and phytochemicals. International Journal of Molecular Sciences, 14(2):4203-4222, 2013.

GONZÁLEZ-ÁVILA, A. M. E.; VÁZQUEZ, G. G. E.; LÓPEZ, B. W. Socioenvironmental affectation of coffee production activity in tributaries of La Suiza River at El Triunfo biosphere reserve, Chiapas. In: ORTEGA-RUBIO, A. (Ed.). Socio-ecological studies in natural protected areas. Ed. Springer, A. Basingstoke, U K, p. 381-403, 2020.

GONZALEZ-RIOS, O. et al. Impact of “ecological” post-harvest processing on the volatile fraction of coffee beans: I. Green coffee. Journal of Food Composition and Analysis, 20(3-4):289-296, 2007a.

GONZALEZ-RIOS, O. et al. Impact of “ecological” post-harvest processing on coffee aroma: II. Roasted coffee. Journal of Food Composition and Analysis, 20(3-4):297-307, 2007b.

HAILE, M.; KANG, W. H. The role of microbes in coffee fermentation and their impact on coffee quality. Journal of Food Quality, Article ID 4836709, 6 pages 2019.

HEČIMOVIĆ, I. et al. Comparative study of polyphenols and caffeine in different coffee varieties affected by the degree of roasting. Food Chemistry, 129(3):991-1000, 2011.

INSTITUTO HONDUREÑO DE CAFÉ - IHCAFE. Exportaciones Y comercialización. 2022. Honduras: Instituto Hondureño de café. Available in: <https://www.ihcafe.hn/>. Access in: March 13, 2024.

INTERNATIONAL COFFEE ORGANIZATION - ICO. The 4th CEOs & global leaders forum: A renewed commitment towards sustainability and farmers’ prosperity in the coffee sector (Press release). 2022. Available in: https://www.ico.org/documents/cy2022-23/pr-335e-cpptf-cglf-oct-2022.pdf. Access in: March 13, 2024.

INTERNATIONAL COFFEE ORGANIZATION - ICO. Market report. 2023. Available in: http://www.ico.org/Market-Report-22-23-e.asp. Access in: March 13, 2024.

JACKELS, S. C.; JACKELS, C. F. Characterization of the coffee mucilage fermentation process using chemical indicators: A field study in Nicaragua. Journal of Food Science, 70(5):C321-C325, 2005.

JEON, J. S. et al. Contents of chlorogenic acids and caffeine in various coffee-related products. Journal of Advanced Research, 17:85-94, 2019.

JESZKA-SKOWRON, M. et al. Chlorogenic acids, caffeine content and antioxidant properties of green coffee extracts: Influence of green coffee bean preparation. European Food Research and Technology, 242(8):1403-1409, 2016.

LAZCANO-SÁNCHEZ, E. et al. Contenido de fenoles, cafeína y capacidad antioxidante de granos de café verdes y tostados de diferentes estados de México. Revista Iberoamericana de Tecnología Postcosecha, 16(2):293-298, 2015.

LEE, Y. K. et al. Quantitative approach in the study of adhesion of lactic acid bacteria to intestinal cells and their competition with enterobacteria. Applied and Environmental Microbiology, 66(9):3692-3697, 2000.

LI, H. et al. Separation and purification of chlorogenic acid by molecularly imprinted polymer monolithic stationary phase. Journal of Chromatography A, 1098(1-2):66-74, 2005.

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

LÓPEZ-ALARCÓN, C.; DENICOLA, A. Evaluating the antioxidant capacity of natural products: A review on chemical and cellular-based assays. Analytica Chimica Acta, 763:1-10, 2013.

MASEK, A. et al. Antioxidant properties of green coffee extract. Forests, 11(5):557, 2020.

MASSAWE, G. A. et al. Yeasts and lactic acid bacteria coffee fermentation starter cultures. International Journal of Postharvest Technology and Innovation, 2:41, 2010.

NANGARE S. et al. Pharmaceutical applications of citric acid. Future Journal of Pharmaceutical Sciences, 7:54, 2021.

PENSON, S. P. et al. Coffee flavour modification process. U.S. Patent No. 8,658,231. Washington, DC: U.S. Patent and Trademark Office. 2014.

PEREIRA, G. et al. Microbiological and physicochemical characterization of small-scale cocoa fermentations and screening of yeast and bacterial strains to develop a defined starter culture. Applied and Environmental Microbiology, 78(15):5395-5405, 2012.

RASOULI, H.; FARZAEI, M. H.; KHODARAHMI, R. Polyphenols and their benefits: A review. International Journal of Food Properties, 20(2):1700-1741, 2017.

RICCI, A. et al. Fast analysis of total polyphenol content and antioxidant activity in wines and oenological tannins using a flow injection system with tandem diode array and electrochemical detections. Food Analytical Methods, 12(2):347-354, 2019.

SANZ URIBE, J. R. et al. Controle los flujos de café y agua en el módulo BECOLSUB. Centro Nacional de Investigaciones de Café (CENICAFÉ), Colombia. 2011. 8p.

SILVEIRA, J. S. et al. Solid-state fermentation as a sustainable method for coffee pulp treatment and production of an extract rich in chlorogenic acids. Food and Bioproducts Processing, 115:175-184, 2019.

SPECIALTY COFFEE ASSOCIATION OF AMERICA - SCAA. SCA Coffee Standards. 2024. Protocols. Seattle, USA. Available in: https://sca.coffee/research/coffee-standards. Access in: 6 May 2024.

SECRETARIA DE AGRICULTURA Y GANADERÍA. Reporte agrometeorológico año IX-No. 05, perspectiva para el periodo correspondiente del 11 de febrero al 20 de febrero de 2021. Available in: <https://infoagro.sag.gob.hn/wp-content/uploads/2021/12/Reporte-Agro-Meteorologico-IX-No-05.pdf>. Access in: 8 May 2024.

SENIDE, D. R.; CHAMBERS, I. V. E. Coffee flavor: A review. Beverages, 6(3):44, 2020.

SHEN, Y. et al. Influence of hot water dip on fruit quality, phenolic compounds and antioxidant capacity of Satsuma mandarin during storage. Food Science and Technology International, 19(6):511-521, 2013.

SHILLINGER, U. et al. A genus-specific PCR method for differentiation between Leuconostoc and Weisella and its application in identification of heterofermentative lactic acid bacteria from coffee fermentation. FEMS Microbiology Letters, 286:222-226, 2008.

SILVA, C. F. Microbial activity during coffee fermentation. In: SCHWAN, R. F. et al. Cocoaand Coffee Fermentations. CRC Press, p. 368-423, 2014.

SINAGA, S. H.; JULIANTI, E. Physical characteristics of Gayo arabica coffee with semi-washed processing. IOP Conference Series: Earth and Environmental Science, 782:032093, 2021.

SINGLETON, V. L.; ORTHOFER, R.; LAMUELA-RAVENTÓS, R. M. Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods in Enzymology, 299:152-178, 1999.

STEINHAUS, M.; WILHELM, W.; SCHIEBERLE, P. Comparison of the most odour-active volatiles in different hop varieties by application of a comparative aroma extract dilution analysis. European Food Research and Technology, 226(1):45-55, 2007.

TRANDAFIR, I.; NOUR, V.; IONICA, M. E. Antioxidant capacity, phenolic acids and caffeine contents of some commercial coffees available on the Romanian market. Archivos Latinoamericanos de Nutrición, 63(1):87-94, 2013.

VAN WYK, N. et al. The whiff of wine yeast innovation: strategies for enhancing aroma production by yeast during wine fermentation. Journal of Agricultural and Food Chemistry, 67(49):13496-13505, 2019.

VELMOUROUGANE, K. Effects of wet processing methods and subsequent soaking of coffee under different organic acids on cup quality. World Journal of Science and Technology, 1(7):32-38, 2011.

VELMOUROUGANE, K. Impact of natural fermentation on physicochemical, microbiological and cup quality characteristics of Arabica and Robusta coffee. Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 83(2):233-239, 2013.

VELMOUROUGANE, K. et al. Use of starter culture in coffee fermentation-effect on demucilisation and cup quality. Indian Coffee, 72(1/2):31-34, 2008.

WANG, Y.; HO, C-T. Polyphenolic chemistry of tea and coffee: A century of progress. Journal of Agricultural and Food Chemistry, 57(18):8109-8114, 2009.

WOLFE, K.; WU, X.; LIU, R. H. Antioxidant activity of apple peels. Journal of Agricultural and Food Chemistry, 51(3):609-614, 2003.

XIE, C. et al. Investigation of isomeric transformations of chlorogenic acid in buffers and biological matrixes by ultraperformance liquid chromatography coupled with hybrid quadrupole/ion mobility/orthogonal acceleration time-of-flight mass spectrometry. Journal of Agricultural and Food Chemistry, 59(20):11078-1187, 2011.

ZHANG, S. J. Influence of various processing parameters on the microbial community dynamics, metabolomic profiles, and cup quality during wet coffee processing. Frontiers in Microbiology, 10:2621, 2019a.

ZHANG, S. J. et al. Following coffee production from cherries to cup: microbiological and metabolomic analysis of wet processing of coffea arabica. Applied and Environmental Microbiology, 85(6):e02635-18, 2019b.

ZHISHEN, J.; MENGCHENG, T.; JIANMING, W. The determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals. Food Chemistry, 64(4):555-559, 1999.




How to Cite

PONCE, J. A. C. .; MEJÍA, L. F. M. . Effect of demucilagination and soaking in water with organic acids on the microbial, chemical, and sensory characteristics of coffee (Coffea arabica). Coffee Science - ISSN 1984-3909, [S. l.], v. 19, p. e192191, 2024. DOI: 10.25186/.v19i.2191. Disponível em: https://coffeescience.ufla.br/index.php/Coffeescience/article/view/2191. Acesso em: 13 jul. 2024.