| Abstract
| - Of all plant constituents, coffee has one of the highest concentrations of chlorogenic acids. Whenroasting coffee, some of these are transformed into chlorogenic acid lactones (CGL). We have studiedthe 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 comparisonof 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 abundantlactone in C. arabica and C. canephora, reaching peak values of 230 ± 9 and 254 ± 4 mg/100 g (dryweight), respectively, at light medium roast (∼14% weight loss). 4-CQL was the second most abundantlactone (116 ± 3 and 139 ± 2 mg/100 g, respectively. The maximum amount of CGL representsapproximately 30% of the available precursors. The relative levels of 3-CQL and 4-CQL in roastedcoffee were reverse to those of their precursors in green coffee. This suggests that roasting causesisomerization of chlorogenic acids prior to the formation of lactones and that the levels of lactones inroasted coffee do not reflect the levels of precursors in green coffee. Keywords: Coffee; coffee roasting; chlorogenic acid lactones; quinides
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