The 12th International Conference on Instrumental Analysis-Modern Trends and Applications (20-23 September 2021, Virtual Event)

abstract

English

Coffee represents important global commodity and constitutes a significant fraction of the export economy of many countries. Coffee as brewed drink prepared from roasted coffee beans is one of the most widely consumed beverages in the world. Consumption of this beverage generates huge amounts of solid residues. An estimated percentage of around 90% of the brewed coffee ends up though in the form of so-called Spent Coffee Grounds (SCG). With an estimated average of 11 grams of fresh ground coffee going into each cup, around 381,000 tonnes of ground coffee are brewed every year, resulting in an estimated quarter of a million tonnes of wet SCG [1]. This material is valorised according to the latest trends and a number of valuable products can be obtained from it. Fresh SCG or SCG after valorisation can also be used as a fertilizer due to the content of some elements and the large water retention capacity [2,3]. However, the use of SCG as a fertilizer is hindered by the content of caffeine, tannins, and phenolics which act as phytotoxins. In the presented work, we studied detoxification of SCG using oxidizing agents, so that SCG could be used for fertilizer preparation. Detoxification efficiency was tested using HPLC by determining the individual phenolic compounds content in the SCG water extract (1:10 solid–water ratio). An Agilent Infinity 1260 HPLC with DAD detector was used during the study. Stationary phase was formed by a Kinetex EVO C18 column and mobile phase consisted of the mixture of acetonitrile and water with 2% formic acid. The results of this study gave the successful detoxification of SCG using the proposed method. The concentration of individual phenolic compounds in the detoxified SCG fell from tens of mg/kg below the detection limit of HPLC (0.3 mg/kg chlorogenic acid, 0.2 mg/kg caffeic acid, 0.1 mg/kg ferulic acid, and 0.6 mg/kg gallic acid). Content of caffeine in detoxified SCG fell by more than half in comparison to fresh SCG. In addition, the possibility of repeated use of an oxidizing agent for SCG detoxification was studied in this work. The results of this study proved that detoxified SCG has significant potential for use in the agricultural industry as a fertilizer. References 1. Kourmentza, C.; Economou, C.N.; Tsafrakidou, P.; Kornaros, M. Spent coffee grounds make much more than waste: Exploring recent advances and future exploitation strategies for the valorization of an emerging food waste stream. J. Clean. Prod. 2018, 172, 980–992. 2. Kovalcik, A.; Obruca, S.; Marova, I. Valorization of spent coffee grounds: A review. Food Bioprod. Process. 2018, 110, 104–119. 3. Ballesteros, L.F.; Teixeira, J.A.; Mussatto, S.I. Chemical, Functional, and Structural Properties of Spent Coffee Grounds and Coffee Silverskin. Food Bioprocess Technol. 2014, 7, 3493–3503.

spent coffee grounds, detoxification, HPLC, chromatography, environment

JUGLOVÁ, Z.; DIVIŠ, P.; MAŇÁKOVÁ, H.

10. 12. 2021

MDPI

BASEL

2076-3417

Applied Sciences - Basel

Swiss Confederation

91

91

166

https://doi.org/10.3390/app112411767