Role of roasting conditions in the level of chlorogenic acid content in coffee beans: correlation with coffee acidity.

Total chlorogenic acids of nine isomers from seven commercial green and roasted coffee beans ranged from 34.43 +/- 1.50 to 41.64 +/- 3.28 mg/g and from 2.05 +/- 0.07 to 7.07 +/- 0.16 mg/g, respectively. Methanol/water (7:3) extracts from four commercial green coffee beans roasted at different conditions (230 degrees C, 12 min; 24 degrees C, 14 min; 250 degrees C, 17 min; and 250 degrees C, 21 min) were also analyzed for chlorogenic acids. The total chlorogenic acid found in green coffee beans ranged from 86.42 +/- 2.04 to 61.15 +/- 1.40 mg/g. Total chlorogenic acids present were reduced in accordance with the intensity of roasting conditions. When green beans were roasted at 230 degrees C for 12 min and at 250 degrees C for 21 min, total chlorogenic acid content was reduced to nearly 50% and to almost trace levels, respectively. The results indicate that roasting conditions play an important role in chlorogenic acid content in roasted coffee beans. A general correlation between total caffeoylquinic acids and pH was observed.