Characterization of the polymerization of furfuryl alcohol during roasting of coffee

Abstract

The polymerization of furfuryl alcohol contributes to the formation of the brown colour in heated foods, in addition to the Maillard and caramelization reactions. During the heating of food, furfuryl alcohol is formed via the degradation of quinic acid or 1,2-enediols. Furfuryl alcohol is a mutagenic compound. In acidic conditions it is able to polymerize and form aliphatic polymers that show a brown colour. Herein we show that furfuryl alcohol polymerizes in a model system by incubating it in 1 M HCl at room temperature. Some of the reaction products are dimers, trimers, tetramers, and pentamers with methylene linkages. The degree of polymerization and the amount of those furfuryl alcohol oligomers increased with increasing reaction time. The results of this model system were used to characterize the polymerization of furfuryl alcohol which is produced during roasting of coffee. The coffee was roasted at 210 °C for 2, 3, 4, 5, and 6 min with a home coffee roaster. Furfuryl alcohol and its dimer were found in roasted coffee after 2 and 3 min of roasting respectively, reaching a maximum amount after 4 min. Perhaps due to further reactions, the dimeric furfuryl alcohol concentration starts to decrease after 4 min. We propose that the polymers of furfuryl alcohol contribute to the brown colour of roasted foods.

The Food and Beverage Occurrence of Furfuryl Alcohol and β-myrcene – Two Emerging Potential Human Carcinogens?

“…Our new data on coffee with an average of 251 mg/kg and a maximum of 408 mg/kg corresponds well to the previous data. The occurrence of furfuryl alcohol in coffee is attributable to the roasting process [5]. This observation parallels the high content of furan found in coffee compared to other foods [24].…”

“…The production and processing of foods and beverages may invariably lead to significant changes in the chemical composition of the products. The Maillard reaction, which yields furanic compounds such as furfural and 5-hydroxymethylfurfural (HMF) and furfuryl alcohol, among other products, is common during processes that involve heating or roasting [1][2][3][4][5]. Furfuryl alcohol is a food contaminant, which occurs in significant amounts in thermally processed foods such as coffee, fruit juices, baked foods and in wood-aged alcoholic beverages such as wines, brandies, and whiskies as a result of enzymatic or chemical reduction of furfural [6][7][8] and in butter, as well as in butterscotch when used as a flavoring agent [9].…”

“…Furfuryl alcohol is a food contaminant, which occurs in significant amounts in thermally processed foods such as coffee, fruit juices, baked foods and in wood-aged alcoholic beverages such as wines, brandies, and whiskies as a result of enzymatic or chemical reduction of furfural [6][7][8] and in butter, as well as in butterscotch when used as a flavoring agent [9]. Furfuryl alcohol may also be formed via the degradation of quinic acid or 1,2-enediols during heating of foods such as coffee beans [5]. In acidic conditions, furfuryl alcohol polymerizes to form aliphatic polymers that give a brown colouration to foods [5].…”

“…Furfuryl alcohol may also be formed via the degradation of quinic acid or 1,2-enediols during heating of foods such as coffee beans [5]. In acidic conditions, furfuryl alcohol polymerizes to form aliphatic polymers that give a brown colouration to foods [5].…”

Characterizations of furfuryl alcohol oligomer/polymerization catalyzed by homogeneous and heterogeneous acid catalysts

“…The chemical structures and morphology of the PFA and PFA derived carbon were demonstrated by multiple characterization investigation: Raman spectroscopy [3,[19][20][21], FT-IR spectroscopy [22,23], UV-visible spectroscopy [24], solid-state 1 H and 13 C-NMR spectroscopy [22,23], high-performance liquid chromatography [24], scanning electron microscope (SEM) [11], and high-resolution transmission electron microscopy (HRTEM) [25]. According to the reported polymerized structures, the humin structure contains methylene linkage furan rings [26,27], dimethylene ether linkage [20], γ-diketone [28], conjugated double bond sequence [3,23,29], and branched species [30,31].…”