title: Investigations on the high molecular weight foaming fractions of espresso coffee.
abstract: The target of the present work was the chemical, technological, and sensorial characterization of the brown polymers (foaming fractions) of freshly prepared espresso coffee. The total foaming fraction (TFF) was precipitated with ammonium sulfate from the defatted freshly prepared beverage and then subfractionated by adding 2-propanol/water to give an insoluble fraction (foaming fraction A, FFA) and a soluble fraction (foaming fraction B, FFB). The former is almost colorless, has a higher molecular weight and a lower nitrogen content, and contains mostly polysaccharides, whereas the latter has a lower molecular weight and a higher protein/melanoidin content, which results in a darker color. FFB showed greater foaming capability, but FFA contributed to the stability of the foam. FFB was further fractionated with solid-phase extraction and characterized by different analytical methods (size exclusion chromatography, UV, HPLC-DAD, 1H NMR). All of the melanoidin-rich fractions showed antioxidant properties with the 2,2-diphenyl-1-picrylhydrazyl hydrate method.
authors.affiliation: Department of Agri-Food Molecular Sciences, Laboratory of Food Chemistry and Mass Spectrometry, University of Milan, Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: D'Agostina
authors.forename: Giovanna
authors.initials: G
authors.lastname: Boschin
authors.forename: Francesca
authors.initials: F
authors.lastname: Bacchini
authors.forename: Anna
authors.initials: A
authors.lastname: Arnoldi
mesh_terms: D000975:Antioxidants / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D005591:Chemical Fractionation; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D003069:Coffee / Q000737:chemistry*; D005524:Food Technology; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011108:Polymers / Q000032:analysis / Q000737:chemistry
chemical_list: D000975:Antioxidants; D002241:Carbohydrates; D003069:Coffee; D011108:Polymers; C011908:melanoidin polymers