Phenolic compounds in coffee

Abstract

Phenolic compounds are secondary metabolites generally involved in plant adaptation to environmental stress conditions. Chlorogenic acids (CGA) and related compounds are the main components of the phenolic fraction of green coffee beans, reaching levels up to 14 % (dry matter basis). These compounds have a number of beneficial health properties related to their potent antioxidant activity as well as hepatoprotective, hypoglycemic and antiviral activities. The main groups of CGA found in green coffee beans include caffeoylquinic acids, dicaffeoylquinic acids, feruloylquinic acids, p-coumaroylquinic acids and mixed diesters of caffeic and ferulic acids with quinic acid, each group with at least three isomers. During coffee processing, CGA may be isomerized, hydrolyzed or degraded into low molecular weight compounds. The high temperatures of roasting also produce transformation of part of CGA into quinolactones and, along with other compounds, melanoidins. This review focuses on the chemical characteristics, biosynthesis, and distribution of CGA and related compounds in coffee. The influence of genetic, physiological and environmental factors as well as processing on the chemical composition of coffee beans is discussed. The impact of CGA composition of green coffee on cup quality is also approached. Despite the existence of substantial published information on the total levels of CGA in coffee, more research is needed on the composition of minor phenolic compounds and specific CGA isomers (and related substances) in green and roasted coffee beans, as well as their impact on coffee quality. Key words: Coffea, chlorogenic acids, chlorogenic acid lactones, coffee quality, coffee processing, coffee roasting, quinides. Compostos fenólicos em café:Os compostos fenólicos são metabólitos secundários de plantas envolvidos na adaptação a condições de estresse ambiental. Os ácidos clorogênicos (CGA) e compostos relacionados são os principais componentes da fração fenólica dos grãos de café verde, alcançando teores de até 14 % (em peso seco). Estes compostos apresentam propriedades benéficas à saúde, não só devido à sua potente atividade antioxidante, mas também como agentes hepatoprotetores, hipoglicemiantes, e antivirais. Os principais grupos de CGA encontrados nos grãos de café verde incluem os ácidos cafeoilquínicos, dicafeoilquínicos, feruloilquínicos, p-cumaroilquínicos e ésteres mixtos dos ácidos cafeico e ferúlico com ácido quínico, com pelo menos três isômeros por grupo. Durante o processamento do café, os CGA podem ser parcialmente isomerizados, hidrolizados ou degradados a compostos de baixo peso molecular. As altas temperaturas observadas no processo de torrefação produzem também a formação de lactonas e a polimerização dos CGA com outros componentes do café para formar melanoidinas. Esta revisão aborda as características químicas, a biosíntese e a distribuição dos CGA e compostos relacionados nos grãos de café. A influência de fatores que modificam a composição dos grãos verdes, tais como genéticos, fisiológicos ...

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

“…These results are also in agreement with the total chlorogenic acids amounts reported for roasted coffees from different origins and varieties. 29,30 Although higher amounts of caffeoylquinic acids in Robusta coffees than in Arabica ones have been extensively reported, 21 other authors have found less amounts of CQAs in Robusta coffees. 31,32 This could be because both, the origin of coffee and the higher loss of chlorogenic acids in Robusta coffee during roasting process.…”

Discrimination of commercial roasted and ground coffees according to chemical composition

“…6,11,13,14,[17][18][19][20][21] The roasting process promotes the degradation of trigonelline and chlorogenic acid (CGA), 19,22 causing variation in their concentrations depending on the presence and on the type of defective beans present. 20,23 Higher levels of trigonelline and nicotinic acid (product of the trigonelline degradation) have been reported for roasted arabica coffee, and higher levels of CGAs have been reported for roasted robusta coffee. 11,14,17,18,24 Cafestol is present in both species.…”

Compostos bioativos em café integral e descafeinado e qualidade sensorial da bebida

“…A atividade antioxidante desses compostos deve-se principalmente às suas propriedades redutoras e estrutura química. Estas características desempenham um papel importante na neutralização ou seqüestro de radicais livres e quelação de metais de transição (Daglia et al, 2000;Farah & Donangelo, 2006;Souza et al, 2007).…”