High Molecular Weight Melanoidins from Coffee Brew

E.K. Bekedam, H.A. Schols, T. van Boekel, G. Smit

Research output: Contribution to journalArticleAcademicpeer-review

155 Citations (Scopus)

Abstract

The composition of high molecular weight (HMw) coffee melanoidin populations, obtained after ethanol precipitation, was studied. The specific extinction coefficient (Kmix) at 280, 325, 405 nm, sugar composition, phenolic group content, nitrogen content, amino acid composition, and non-protein nitrogen (NPN) content were investigated. Results show that most HMw coffee melanoidins are soluble at high ethanol concentrations. The amino acid composition of the HMw fractions was similar, while 17% (w/w) of the nitrogen was NPN, probably originating from degraded amino acids/proteins and now part of melanoidins. A strong correlation between the melanoidin content, the NPN, and protein content was found. It was concluded that proteins are incorporated into the melanoidins and that the degree of chemical modification, for example, by phenolic groups, determines the solubility of melanoidins in ethanol. Although the existence of covalent interaction between melanoidins and polysaccharides were not proven in this study, the findings suggest that especially arabinogalactan is likely involved in melanoidin formation. Finally, phenolic groups were present in the HMw fraction of coffee, and a correlation was found with the melanoidin concentration
Original languageEnglish
Pages (from-to)7658-7666
JournalJournal of Agricultural and Food Chemistry
Volume54
Issue number20
DOIs
Publication statusPublished - 2006

Keywords

  • chemical-characterization
  • maillard reaction
  • liquid-chromatography
  • espresso coffee
  • roasted coffee
  • arabica coffee
  • foam stability
  • amino-acids
  • hot-water
  • green

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