EXPLORING THE POTENTIAL OF SPENT COFFEE GROUNDS 100 % COFFEA ARABICA REGARDING CHEMICAL COMPOUNDS

Abstract

Worldwide coffee consumption continues to grow, resulting in the production of co-products generated during its processing. One of these co-products is spent coffee grounds (SCG), which was the subject of our research, focusing on the quantitative determination and evaluation of selected physicochemical parameters in coffee samples and the SCG derived from them. The samples consisted of 100 % C. arabica from Peru, Kenya, Colombia, Cuba, and Vietnam, roasted to a medium level. First, we analyzed 5 extract samples prepared from roasted coffee beans, and subsequently 5 extract samples of SCG obtained from these beans. The analysis included determining pH, dry matter content, total antioxidant capacity (TAC), total polyphenol content (TPC), caffeine, and chlorogenic acids. The pH values measured in coffee beans ranged from 4.733 to 5.113, and in SCG from 4.808 to 5.138, with both being slightly acidic.  The highest dry matter content was observed in sample 5B, at 98.280 %, while the lowest was in 4G, at 93.030 %, related to the combination of temperature and time applied during the SCG drying process. The percentage inhibition of DPPH showed the lowest value in coffee bean sample 4B (81.914 %), while the highest was found in SCG sample 2G (88.021 %). In contrast, the total polyphenol content (TPC) in the coffee beans samples was higher (40.024 to 51.074 g GAE. kg^-1 (GAE – gallic acid equivalent)) compared to the SCG samples (6.985 to 14.569 g GAE. kg^-1). The highest caffeine content was found in coffee bean sample 5B (9.826 mg.g⁻¹). In the case of SCG, the average caffeine content decreased due to leaching into the coffee extract, with the highest value recorded in sample 4G at 3.438 mg.g⁻¹. The average chlorogenic acids (CGAs) content in coffee beans ranged from 20.745 to 25.741 mg.g^-1, and in SCG from 6.153 to 10.867 mg.g^-1. Our results suggest that SCG represent a natural source of bioactive compounds that could be reused, thereby contribute to waste minimization disposal and environmental impact.