Effect of roasting on antioxidant and anticholinesterase capacities of coffee

Abstract

The aim of the study was to investigate the effect of the roasting degree on total phenolic and flavonoid contents, antioxidant and anticholinesterase activities of the hexane, acetone, ethanol and water extracts of coffee. The antioxidant capacity of the water extracts prepared according to the brewing procedure of Turkish coffee was measured for the first time by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and cupric ion reducing antioxidant capacity (CUPRAC) assays. The in vitro anticholinesterase activity of the coffee extracts and caffeine was determined for the first time. Water extracts of the coffee samples exhibited the highest 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) cation radical scavenging, DPPH free radical scavenging and CUPRAC effects. The hexane extract of coffee roasted for 25 min showed the highest acetylcholinesterase inhibitory activity among the tested extracts. Caffeine, which is known to have therapeutic effect against Alzheimer's disease, was found to possess almost the same anticholinesterase activity as galanthamine. The roasting degree had an irregular effect on the antioxidant and anticholinesterase activities of the coffee extracts. The caffeine contents in extracts of coffee roasted for 25 min, which had strong anticholinesterase effect, were determined by HPLC, and the water extract was found to possess the highest caffeine content.