Sustainable Management and Valorization of Spent Coffee Grounds Through the Optimization of Thin Layer Hot Air-Drying Process
- 14 Downloads
The spent coffee ground is a by-product of the coffee industry with high potential because of its beneficial properties for health, however, due to high water content, it is necessary to stabilize it without affecting bioactive capacities. The main objective of this work was to evaluate the effect of different convective drying conditions, on some technological and functional properties of the spent coffee ground and to determine the thermal degradation kinetics of chlorogenic acids. The methodology included the optimization of the drying process conditions of spent coffee ground: temperature (40–60 °C), air flow (1.0–2.0 m/s) and cake thickness (0.01–0.02 m). Effective diffusion coefficient, moisture, water activity, water and oil holding capacity, antioxidant capacity, caffeine, and seven chlorogenic acids were determined. The results showed that the best drying conditions were 60 °C, 2.0 m/s, 1.28 cm which allows retaining 84.24% of total polyphenols and 66.00% of the antioxidant capacity. Chlorogenic acids showed thermal degradation kinetics of first order under the optimal process conditions. In general, it is concluded that the convective drying process is a valid technique for processing of coffee grounds, as it allows the preservation of antioxidant compounds with a potentially beneficial effect on health, providing a stabilized low moisture content that can be used in food applications.
KeywordsSpent coffee ground Effective diffusion coefficient Bioactive properties Technological properties Chlorogenic acids
The authors give special thanks to COLCIENCIAS for supporting, by the agreement 727-2015 scholarship. In addition, a special thanks to Universidad de Antioquia for the donation of the raw material. The authors are grateful for the financial support provided by CONICYT through FONDECYT project 1160811 (Cristian Ramírez) and 1181270 (Ricardo Simpson).
This work was supported by the Administrative Department of Science, Technology, and Innovation—Colciencias, Colombia [Convocatoria 727 de 2015].
Compliance with Ethical Standards
Conflict of interest
The authors declare that have no conflict of interest.
- 20.M. Misra, S. K. Mohapatra, and K. & N. V., Methods, systems, and apparatus for obtaining biofuel from coffee and fuels produced therefrom. Patent 8591605 B2, 2013.Google Scholar
- 21.Baechler, R.: Process for extracting terpens from spent coffee grounds. Patent 0819385, B1 (2002)Google Scholar
- 28.Duarte, Y. et al.: Effects of blanching and hot air drying conditions on the physicochemical and technological properties of yellow passion fruit (Passiflora edulis Var. Flavicarpa) by-products. J. Food Process. Eng. 40(3), 0–9, 2017.Google Scholar
- 29.AOAC: Official Methods of Analysis of AOAC International, 20th ed. Rockville: Association of Official Analytical Chemists, 2016.Google Scholar
- 32.Crank, J.: The Mathematics of Diffusion, 2d ed. Oxford University Press, Oxford (1975)Google Scholar
- 39.D. I. für Normung, DIN 10767:Analysis of coffee and coffee products; determination of chlorogenic acids content; HPLC method. 1992.Google Scholar
- 44.Ramírez, C., Astorga, V., Nuñez, H., Jaques, A., Simpson, R.: Anomalous diffusion based on fractional calculus approach applied to drying analysis of apple slices: the effects of relative humidity and temperature. Food Process Eng. e12549, 1–10 (2017)Google Scholar
- 45.Zogzas, N., Maroulis, Z.B.: Moisture diffusivity data compilation in foodstuff. Dry. Technol. 2013, 37–41 (2007)Google Scholar
- 48.Akoy, E.O.M.: Experimental characterization and modeling of thin-layer drying of mango slices. Int. Food Res. J. 21(5), 1911–1917 (2014)Google Scholar
- 51.J. Salvador, Aplicación de microperforaciones utilizando laser-CO2 en el proceso de liofilización de alimentos: efecto en el tiempo de secado primario. Universidad Tecnica Federico Santa María, 2018.Google Scholar
- 53.de Moraes Crizel, T., Jablonski, A., de OliveiraRios, A., Rech, R., Flôres, S. H.: Dietary fiber from orange byproducts as a potential fat replacer. LWT Food Sci. Technol. 53(1), 9–14 (2013)Google Scholar
- 59.Puerta, G.: La humedad controlada del grano preserva la calidad del café. Cenicafé 352, 1–8 (2006)Google Scholar
- 60.D. L. Aurelio, R. G. Edgardo, S. Navarro-Galindo, Thermal kinetic degradation of anthocyanins in a roselle (Hibiscus sabdariffa L. cv. ’Criollo’) infusion. Int. J. Food Sci. Technol., 43(2), 322–325, 2008.Google Scholar