Abstract
Spent coffee grounds (SCG) have grown its popularity as a low-cost and versatile resource in multiple application fields. The economic potential of SCG is highlighted by its abundance and rich contents of various beneficial compounds, such as polyphenols, polysaccharides, amino acids, antioxidants, etc. This study aimed to evaluate the content of lipid hydroperoxide (LP), total phenolic content (TPC), flavonoid content (TFC) and antioxidant in SCG’s extract. The coffee grounds were extracted using n-hexane and methanol in three different SCG/solvent (w/v) ratios: 1 : 10, 1 : 15 and 1 : 20. Both conventional and advanced extraction methods were employed, including Maceration (MAC), Soxhlet (SOX), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE). The highest contents of LP and TPC were 0.0191 mM and 13.466 mg gallic acid (AG)/g dry weight by using UAE at the ratio of 1 : 20. With the same ratio, TFC peaked the highest point at 31.15 mg quercetin/g dry weight when extracted by MAE method. The oil recovery yield was in the range from 9.42 % to 17.96 %. The phenolic recovery yield was between 5.76 % and 12.3 %. The results indicated the high antioxidant capacity of the extract.
