title: Isolation and determination of alpha-dicarbonyl compounds by RP-HPLC-DAD in green and roasted coffee.
abstract: Glyoxal, methylglyoxal, and diacetyl formed as Maillard reaction products in heat-treated food were determined in coffee extracts (coffee brews) obtained from green beans and beans with different degrees of roast. The compounds have been reported to be mutagenic in vitro and genotoxic in experimental animals in a number of papers. More recently, alpha-dicarbonyl compounds have been implicated in the glycation process. Our data show that small amounts of glyoxal and methylglyoxal occur naturally in green coffee beans. Their concentrations increase in the early phases of the roasting process and then decline. Conversely, diacetyl is not found in green beans and forms later in the roasting process. Therefore, light and medium roasted coffees had the highest glyoxal and methylglyoxal content, whereas dark roasted coffee contained smaller amounts of glyoxal, methylglyoxal, and diacetyl. For the determination of coffee alpha-dicarbonyl compounds, a reversed-phase high performance liquid chromatography with a diode array detector (RP-HPLC-DAD) method was devised that involved the elimination of interfering compounds, such as chlorogenic acids, by solid phase extraction (SPE) and their derivatization with 1,2-diaminobenzene to give quinoxaline derivatives. Checks of SPE and derivatization conditions to verify recovery and yield, respectively, resulted in rates of 100%. The results of the validation procedure showed that the proposed method is selective, precise, accurate, and sensitive.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Pavia, Via Taramelli 12, 27100 Pavia, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Daglia
authors.forename: Adele
authors.initials: A
authors.lastname: Papetti
authors.forename: Camilla
authors.initials: C
authors.lastname: Aceti
authors.forename: Barbara
authors.initials: B
authors.lastname: Sordelli
authors.forename: Valentina
authors.initials: V
authors.lastname: Spini
authors.forename: Gabriella
authors.initials: G
authors.lastname: Gazzani
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D040503:Coffea / Q000737:chemistry*; D003931:Diacetyl / Q000032:analysis / Q000302:isolation & purification; D006037:Glyoxal / Q000032:analysis* / Q000302:isolation & purification; D006358:Hot Temperature; D011765:Pyruvaldehyde / Q000032:analysis* / Q000302:isolation & purification; D012639:Seeds / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D006037:Glyoxal; D011765:Pyruvaldehyde; D003931:Diacetyl