Effects of postharvest processing on the bioactive compounds in Arabica coffee

Abstract

Coffee is known as the most popular beverage after water. Arabica coffee accounts for 70% of the overall world coffee production.

Coffee postharvest operations resulting in the production of green coffee, storage and roasting are important processing steps. Comparison of coffee postharvest treatments, storage and roasting temperatures were done to maximise yield of beneficial compounds. The study used the mechanically demucilaged coffee beans. The soaked and non-soaked parchment coffee samples were dried at 40 oC (20% RH), 50 oC (15% RH), 60 oC (15% RH) and 70 oC (10% RH). The soaked and non-soaked parchment coffee samples, dried at 40 oC (20 %RH), were selected to study effects of storage conditions (15 oC, 60% RH and 30 oC, 30% RH). After that, the samples were roasted and extracted. Moisture content, %weight loss and colour were measured to assure consistency of roasting levels of coffee samples.

The analysis by HPLC showed highest concentration of chlorogenic acid, caffeine, trigonelline, α-tocopherol in the coffee beans which were non-soaked and stored at 15 oC and 60% RH for 6 month and roasted at light level (180 oC, 3 min). Positive correlation was found between total phenolic compounds content and the anti-oxidant activities (FRAP and ORAC). Moreover, the highest contents of cafestol and kahweol were found in green coffee. The soaked and dark roasted coffee samples received the highest score of consumer acceptance.