Blood glucose response of robusta coffee with different roasting levels: light and dark

The aims of this study were to analyze the total chlorogenic acid and total caffeine in robusta coffee roasted at light and dark levels; and the effect on clinical blood glucose response after its consumption. Original robusta coffee from Lampung was roasted into light and dark. Chlorogenic acids and caffeine in coffee brew were determined by using RP-HPLC, while α-glucosidase inhibitor was measured by UV-VIS spectrophotometer technique. The ethics of this research was approved by the Ethical Commission for Research Involving Human Subjects, IPB University. Blood glucose levels were assayed in ten healthy subjects after overnight fasting and consumption of coffee brew with and without references food (glucose and white bread). When light-roasted coffee was compared to dark-roasted coffee, the 3-CQA (O-caffeoylquinic acid) content reduced by 39%, 4-CQA by 41%, and 5-CQA by 44% in terms of chlorogenicacids. The amount of caffeine in the coffee brew (2.75–2.81 g/100 g) was unaffected by the roasting level. Inhibition of the α-glucosidase activity of light-roasted coffee the brew was 85% higher than dark-roasted coffee. While coffee brew alone did not significantly suppress postprandial glucose absorption, the combination of light-roasted coffee with glucose led to a greater reduction in blood glucose levels, particularly −2.4 mg/dL/min during the 45–60 minute post-consumption period. These results suggest that lightly roasted Robusta coffee may have potential in modulating postprandial glycemic response in healthy individuals when consumed acutely. Key words: α-Glucosidase; carbohydrate; coffee; chlorogenic acids; caffeine.