Effect of Roasting on the Formation of Chlorogenic Acid Lactones in Coffee

Abstract

Of all plant constituents, coffee has one of the highest concentrations of chlorogenic acids. When roasting coffee, some of these are transformed into chlorogenic acid lactones (CGL). We have studied the formation of CGL during the roasting of coffee beans in Coffea arabica cv. Bourbon; C. arabicacv. Longberry; and C. canephora cv. Robusta. Individual CGL levels were determined by comparison of HPLC peaks with those of synthetic CGL standards. Seven CGL were identified: 3-caffeoylquinic-1,5-lactone (3-CQL), 4- caffeoylquinic-1,5-lactone (4-CQL), 3-coumaroylquinic-1,5-lactone (3-pCoQL), 4-coumaroylquinic-1,5-lactone (4-pCoQL), 3-feruloylquinic-1,5-lactone (3-FQL), 4-feruloylquinic-1,5-lactone (4-FQL), and 3,4-dicaffeoylquinic-1,5-lactone (3,4-diCQL). 3-CQL was the most abundant lactone in C. arabica and C. canephora, reaching peak values of 230 +/- 9 and 254 +/- 4 mg/100 g (dry weight), respectively, at light medium roast ( approximately 14% weight loss). 4-CQL was the second most abundant lactone (116 +/- 3 and 139 +/- 2 mg/100 g, respectively. The maximum amount of CGL represents approximately 30% of the available precursors. The relative levels of 3-CQL and 4-CQL in roasted coffee were reverse to those of their precursors in green coffee. This suggests that roasting causes isomerization of chlorogenic acids prior to the formation of lactones and that the levels of lactones in roasted coffee do not reflect the levels of precursors in green coffee.

Potential antioxidant of brazilian coffee from the region of Cerrado

“…It was observed that when comparing the concentration of phenolic compounds in green coffee grains and in dark roasts, there was a linear decrease in total phenolic compounds (Sacchetti et al, 2009). Farah et al (2005) reported that some phenolic compounds present in coffee, such as chlorogenic acids, are degraded into low molecular weight compounds through the roasting process and are partly transformed into quinolactones due to dehydration and the formation of intermolecular bonds.…”

Analytical methods applied for the characterization and the determination of bioactive compounds in coffee

“…However, the total CGA content of green coffee beans may vary not only according to genetics-species but also to the degree of maturation, agricultural practices, climate and soil [16,17]. For example CGA content found in different coffee species of wild Coffea genetic resources varies between 0.61 and 1.05 % for Coffea sp.…”

“…During roasting, a part of CGA is isomerized, a part is transformed into quinolactones due to dehydration and formation of an intramolecular bond, and a part is hydrolyzed and degraded into low molecular weight compounds or even reduced [12,13,16]. It depends on parameters of roasting process and coffee preparing [33][34][35].…”

Evaluation of Spent Coffee Obtained from the Most Common Coffeemakers as a Source of Hydrophilic Bioactive Compounds

“…Pure reference standards of 5-caffeoylquinic acid (5-CQA) and caffeine were obtained from Sigma-Aldrich (Steinheim, Germany) and pure reference standards of 3,4-, 3,5-and 4,5-dicaffeoylquinic acids were purchased from Phytolab (Vestenbergsgreuth, Germany). A mixture of 3-CQA, 4-CQA, and 5-CQA was prepared from 5-CQA using the isomerization method of Trugo & Macrae, 20 also described in Farah et al 21 …”