Influence of divalent cations on the extraction of organic acids in coffee determined by GC-MS and NMR

• Published in: Heliyon Vol. 10; no. 5; p. e26625
• Main Authors: Bratthäll, Tove, Figueira, João, Nording, Malin L.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.03.2024; Elsevier
• Subjects: Calcium; Coffee brewing; GC-MS; Magnesium; NMR; Organic acid; GC-MS; NMR; Magnesium; Calcium; Organic acid; Coffee brewing
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2024.e26625

The perceived flavor of coffee varies depending on the composition of the brewing water, and the influencing mechanisms are poorly understood. To investigate the effect of dissolved divalent cations on the extraction of organic acids in coffee, magnesium and calcium chloride salts were added pre- and post-brew. Citric, malic, lactic and quinic acid were analyzed using gas chromatography – mass spectrometry and nuclear magnetic resonance techniques. At concentrations typically found in drinking water, the salts resulted in limited variation of the acid content, while ten-fold higher salt concentrations produced more pronounced variations. Comparisons between pre- and post-brew additions showed similar acid content in most cases, suggesting that extraction of acids proceeds independent of the water composition. Interactions taking place post-brew may, however, influence the perceived flavor. A scientific basis for water quality recommendations in the coffee industry is long overdue and this work provides experimental and analytical contributions to continued research. [Display omitted] •Pre- and post-brew effects of divalent ions on organic acids in coffee were investigated.•Regular levels of divalent ions displayed small effects on acid content in coffee.•Ten-fold higher levels of divalent ions displayed larger effects on acid content in coffee.•Extraction of acids in coffee seems to proceed independent of divalent ions.•Perceived flavor of coffee is most likely due to interactions taking place post-brew.