The Chlorogenic Acid and Caffeine Contents in Wet-, Dry- and Monsoon-Processed Commercial Grades of Green and Roasted Indian Coffee Beans.

This research study reports the content of individual chlorogenic acids and caffeine in commercial grades of Indian wet-, dry- and monsoon-processed Arabica and Robusta coffees. It also reports on the composition of roasted coffee beans as obtained by reversed-phase high-performance liquid chromatography (HPLC). A partial study involved roast and beverage quality of a series of roasted coffees of the above, covering the lightest and darkest roasts up to the burnt, especially in the case of dry-and wet- processed Arabica and Robusta coffee. Significant differences with reference to individual chlorogenic acids (CGA), its isomers, sub groups, and the total CGA contents were observed between wet-, dry- and monsoon-processed coffee beans of different main grades, immature and mature dry processed Robusta AB (flat beans) grade green coffee. Monsooned Arabica and Robusta coffees were characterised by significantly higher contents of caffeic acids and had higher total CGA contents than wet- and dry-processed coffees. In the case of wet- and dry-processed Arabica coffee, CGA content steadily decreased during the initial phase, followed by a rapid decrease at extreme degrees of roasting. An apparent increase in 3-CQA and 4-CQA isomers as 5-CQA and di-CQA content decreases is due to the pyrolytic effect on 5-CQA and di-CQA. There is a rapid decrease in all CGA isomers at the darker degree of roast. There is a proportionate increase in feruloylquinic acid (FQA) content from light-medium and medium-dark roasted Arabica and Robusta coffees. From this investigation, it is evident that about 50 percent of CQA and di-CQA content disappeared at a certain degree of roast and/apparent increase in FQA content which may correlate with the roast and beverage quality in both these coffees. There is a considerably higher content of chlorogenic acids and caffeic acid in both monsooned coffees than in wet- and dry-processed. This may be correlated with fully matured coffee beans of dry and monsooning processes. It has also been observed that CGA content rapidly disappears at shorter degree of roasting times in both monsooned Arabica and Robusta coffees. FQA content increases at 5 to 6 minutes roasting time and there is a rapid moisture and roasting loss. This is required for medium to standard roasting of monsooned coffees. The kinetics of chlorogenic acids degradation in different processed Indian Arabica and Robusta coffees during roasting have been studied. The rate of degradation of CQA, di-CQA and FQA sub groups and total CGA content have been reported during roasting