Chlorogenic Acid in Coffee
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Axit Chlorogenic
Discovered in 1932, chlorogenic acids (CGA) represent a large group of esterifying compounds found in green and roasted coffee. During the roasting process, CGA is slowly broken down to form caffeine and quinic acid with about 50% of the original CGA broken down at the medium roasting level
Chlorogenic Acid in Coffee
Quinic acid and caffeine have been linked to increased levels of bitter, physical darkness typically found in dark roast levels
The composition of raw coffee (%)
Coffee has by far the greatest concentration of chlorogenic acid among plant species, accounting for 6-7% in Arabica and up to 10% in Robusta.
CGA in plants is initiated by a number of factors including changing environmental conditions, farming techniques and pest infestation. It's no surprise that robusta grown in harsher conditions contains almost twice as much CGA concentration as arabica.
CGA is similar to caffeine, as CGA levels increase, so does caffeine.
Although the term chlorogenic acid is used to identify a single compound, in reality, there are many isomers with different organoleptic characteristics. Typically, the 3-CGA isomer makes up the majority of coffee compared to mono, di and feruloylquinic in different concentrations.
Research indicates that the isomer "di-CGA" is probably the cause of the bitter/hard taste in coffee. This is true for Robusta coffee, which contains higher concentrations of di-CGA, more bitter flavors.
The latest research has confirmed that coffee contains high concentrations of antioxidants in the range of 200 to 550mg per cup (6oz) – a level far exceeding that of green tea. But although both coffee and tea contain high levels of antioxidants, coffee contains higher levels of simple phenols while tea has a greater catechin content.
Nguồn: coffeechemistry.com
