Role of Degradation Products of Chlorogenic Acid in the Antioxidant Activity of Roasted Coffee

Antioxidant activities of brewed coffees prepared from six commercial brands ranged from 63.13 +/- 1.01 to 96.80 +/- 1.68% at the highest levels tested. Generally, the degree of antioxidant activity of the brewed coffee was inversely proportional to the total chlorogenic acid concentration. A sample obtained from the major chlorogenic acid, 5-caffeoylquinic acid (5-CQA), heated at 250 degrees C exhibited potent antioxidant activity (79.12 +/- 2.49%) at the level of 10 mu g/mL, whereas unheated 5-CQA showed only moderate antioxidant activity (44.41 +/- 0.27%) at the level of 100 mu g/mL. Heat produced relatively high levels of pyrocatechol (2,809.3 mu g/g) and 2-methoxy-4-vinylphenol (46.4 mu g/g) from 5-CQA, and their antioxidant activity levels were 76.57 +/- 3.00 and 98.63 +/- 0.01%, respectively. The results of the present study suggest that roasting degrades chlorogenic acids to form potent antioxidants and thus plays an important role in the preparation of high-antioxidant low-acid coffee.