Isolation and Determination of α-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.

Evaluation of exposures and respiratory health at a coffee processing facility.

“…Diacetyl, 2,3-pentanedione, 2,3-hexanedione, and other compounds such as CO 2 and CO are naturally produced when coffee beans are roasted, and grinding the roasted coffee beans pro duces greater surface area for the off-gassing of these chemicals [Anderson et al 2003;Aki yama et al 2003;Daglia et al 2007;Newton 2002;Nishimura et al 2003;Raffel and Thomp son 2013]. In addition, flavorings added to coffee can contain diacetyl or 2,3-pentanedione.…”

“…Diacetyl, 2,3-pentanedione, other VOCs, and gases such as carbon monoxide (CO) and carbon dioxide (CO 2 ) are naturally produced and released during the coffee roasting process [Duling et al 2016;Raffel and Thompson 2013;Daglia et al 2007;Nishimura et al 2003;Newton 2002]. Grinding roasted coffee beans produces a greater surface area for off-gassing (sometimes called degassing) of these compounds [Akiyama et al 2003].…”

Evaluation of exposures and respiratory health at a coffee roasting and packaging facility.

“…Diacetyl, 2,3-pentanedione, 2,3-hexanedione, other VOCs, and other compounds such as CO 2 and CO are naturally produced when coffee beans are roasted, and grinding the roasted coffee beans produces greater surface area for the off-gassing of these chemicals [Anderson et al 2003;Akiyama et al 2003;Daglia et al 2007;Newton 2002;Nishimura et al 2003;Raffel and Thompson 2013]. Occupational exposure to diacetyl and 2,3-pentanedione can cause loss of lung function and the lung disease obliterative bronchiolitis [NIOSH 2016].…”

Evaluation of exposures and respiratory health at a coffee roasting and packaging facility and attached retail café.

“…Diacetyl, 2,3-pentanedione, 2,3-hexanedione, other VOCs, and other chemicals such as CO and CO 2 are naturally produced when coffee beans are roasted, and grinding the roasted coffee beans produces greater surface area for off-gassing of these chemicals [Anderson et al 2003;Akiyama et al 2003;Daglia et al 2007;Newton 2002;Nishimura et al 2003;Raffel and Thompson 2013]. While TWA personal and area concentrations of diacetyl and 2,3-pentanedione were low (max 5.9 ppb), peak exposures to alpha-diketones occurred during specific tasks involving the manual handling of roasted coffee beans (e.g., scooping roasted beans from storage bin for weigh/pack and grinding coffee beans).…”