Incorporation of Chlorogenic Acids in Coffee Brew Melanoidins

• Published in: Journal of agricultural and food chemistry 2008-03, Vol.56 (6), p.2055-2063
• Main Authors: Bekedam, E. Koen, Schols, Henk A, Van Boekel, Martinus A. J. S, Smit, Gerrit
• Format: Article
• Language: English
• Subjects: antioxidant activity; beans; Biological and medical sciences; caffeic acid; Caffeic Acids - analysis; Caffeic Acids - chemistry; chemical bonding; Chemical Changes Induced by Processing/Storage; chemical structure; chemical-characterization; chlorogenic; chlorogenic acid; Chlorogenic Acid - chemistry; chromatography; Chromatography, Ion Exchange; Coffea - chemistry; Coffee; coffee (beverage); Coffee - chemistry; Coffee, tea and other stimulative beverage industries; Coumaric Acids - analysis; degradation; electrochemistry; enzyme activity; food composition; Food industries; Fundamental and applied biological sciences. Psychology; Hot Temperature; incorporation; ionic charge; lactones; Maillard reaction; Maillard reaction products; melanoidins; Molecular Weight; phenolic; phenols; Polymers - analysis; Polymers - chemistry; quantitative analysis; quinic; quinic acid; Quinic Acid - analogs & derivatives; Quinic Acid - analysis; Quinic Acid - chemistry; roasted coffee; roasting; Seeds - chemistry; solubility; systems
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf073157k

The incorporation of chlorogenic acids (CGAs) and their subunits quinic and caffeic acids (QA and CA) in coffee brew melanoidins was studied. Fractions with different molecular weights, ionic charges, and ethanol solubilities were isolated from coffee brew. Fractions were saponified, and the released QA and CA were quantified. For all melanoidin fractions, it was found that more QA than CA was released. QA levels correlated with melanoidin levels, indicating that QA is incorporated in melanoidins. The QA level was correlated with increasing ionic charge of the melanoidin populations, suggesting that QA may contribute to the negative charge and consequently is, most likely, not linked via its carboxyl group. The QA level correlated with the phenolic acid group level, as determined by Folin-Ciocalteu, indicating that QA was incorporated to a similar extent as the polyphenolic moiety from CGA. The QA and CA released from brew fractions by enzymes confirmed the incorporation of intact CGAs. Intact CGAs are proposed to be incorporated in melanoidins upon roasting via CA through mainly nonester linkages. This complex can be written as MelCA−QA, in which Mel represents the melanoidin backbone, CA represents CA nonester-linked to the melanoidin backbone, and −QA represents QA ester-linked to CA. Additionally, a total of 12% of QA was identified in coffee brew, whereas only 6% was reported in the literature so far. The relevance of the additional QA on coffee brew stability is discussed.