Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres Spatial distributions of furan and 5-hydroxymethylfurfural in unroasted and roasted Coffea arabica beans Kristen L. Fowble a , Koji Okuda b , Robert B. Cody b , Rabi A. Musah a, ⁎ a University at Albany—State University of New York, Department of Chemistry, 1400 Washington Avenue, Albany, NY 12222, USA b JEOL, Inc., 11 Dearborn Road, Peabody, MA 01960, USA ARTICLE INFO Keywords: Coffea arabica beans Furan 5-Hydroxymethylfurfural Small-molecule spatial distributions Laser ablation direct analysis in real time imaging-mass spectrometry (LADI-MS) Imaging mass spectrometry ABSTRACT For the first time, the spatial distributions of the highly volatile compounds furan and 5-hydroxymethylfurfural (HMF) have been determined in cross sections of green and roasted Coffea arabica beans. The image maps were revealed by laser ablation DART imaging mass spectrometry (LADI-MS). The presence of these compounds was independently confirmed by GC–MS as well as argon DART-MS. Quantification of furan by GC–MS was com- pleted with the final concentrations in roasted and unroasted beans determined to be 96.5 and 4.1 ng/g, re- spectively. Furan was observed to be distributed throughout the tissue of both green and roasted beans, while HMF was localized to the silver skin in green beans. Following roasting, the appearance of HMF was more diffuse. The implications of the broad distribution of furan on the one hand, and localization of HMF on the other, are discussed. 1. Introduction Freshly brewed coffee elicits in humans a composite of sensory ex- periences that engage the faculties of sight (color and consistency), smell (from the fragrance attributes of emitted volatiles) and taste, evoking such descriptors as rich, bold, dark, full-bodied, warm, robust, and the like. Aside from the influence of the chemicals whose appear- ance is defined by the genetic makeup of the specific coffee species, as well as the cultivar and growth conditions, the organoleptic properties of roasted coffee arise from compounds formed through a cascade of heat-promoted chemical transformations including Maillard and Strecker degradation reactions, and caramelization that occur more or less simultaneously during heat processing. The precursors for the formation of these compounds include sugars, amino acids, vitamins, lipids and fatty acids. The identities of the compounds produced and their formation levels are impacted by the relative concentrations of the precursors themselves. However, it is likely that they are also influ- enced by the relative distributions of the precursors within the bean, although this latter possibility has been little investigated because in- formation on their tissue localization remains largely unknown. Several reports have appeared detailing both the health benefits and detriments of coffee brews and their constituent components (Arisseto, Vicente, Ueno, Tfouni, & Toledo, 2011; Monien, Engst, Barknowitz, Seidel, & Glatt, 2012; Zanin, Corso, Kitzberger, Scholz, & Benassi, 2016). While some compounds have been documented to impart health benefits, such as chlorogenic acids which exhibit antioxidant and anti-inflammatory effects (Zanin et al., 2016), others are perceived to have negative health impacts (IARC, 1995; Monien et al., 2012; Neuwirth et al., 2012; Peterson, 2013). Although both are purported to contribute to the sensory properties of the foods in which they appear (Maga & Katz, 1979), furan and 5- hydroxymethylfurfural (HMF) are two compounds whose detection in coffee has raised concerns. Their concentrations in roasted coffee have been observed to range from 38.7–51.341 ng/g and 0.452–6.27 mg/g respectively (Becalski, Halldorson, Hayward, & Roscoe, 2016; Moon & Shibamoto, 2009; Quarta & Anese, 2012; Sijia, Enting, & Yuan, 2014). Both compounds can be derived from several reactions involving a range of different precursors and/or intermediates (Capuano & Fogliano, 2011; Crews & Castle, 2007). HMF has been shown to induce mutagenic and genotoxic effects in bacteria and human cells and pro- mote colon and liver cancer in rats and mice (Monien et al., 2012), although it remains unclear if these effects extend to humans (Capuano & Fogliano, 2011). HMF formation in foods has been found to be af- fected by sugar type, pH, water content and the presence of divalent cations (Gökmen, Açar, Köksel, & Acar, 2007; Gökmen & Şenyuva, 2007; Kroh, 1994). HMF can be formed from the caramelization of sugars such as sucrose (Kroh, 1994) or fructose (Roman-Leshkov, Chheda, & Dumesic, 2006) through formation of a fructofuranosyl ca- tion under thermal treatment and acidic catalysis. Glucose and fructose can also generate HMF through the formation of a dicarbonyl https://doi.org/10.1016/j.foodres.2018.10.052 Received 20 July 2018; Received in revised form 15 October 2018; Accepted 18 October 2018 ⁎ Corresponding author. E-mail address: rmusah@albany.edu (R.A. Musah). Food Research International 119 (2019) 725–732 Available online 19 October 2018 0963-9969/ © 2018 Elsevier Ltd. All rights reserved. T