Authentication of Straight Whiskey by Determination of the Ratio of Furfural to 5-Hydroxymethyl-2-Furaldehyde

Abstract

Bureau of Alcohol, Tobacco and Firearms regulations require that a straight whiskey be aged in a freshly charred oak barrel for a minimum of 2 years and that it not be colored with added caramel. The regulations, however, permit addition of caramel in blended whiskeys. Blended whiskeys are usually produced by mixing a straight whiskey with neutral spirits which causes loss of color intensity. Caramel addition is permitted to compensate for this loss. Thus, it is not possible to authenticate the standard of identity of a straight whiskey by measurement of color intensity. Our investigations suggest that furfural (2-furaldehyde) and 5-hydroxymethyl-2-furaldehyde are imparted into a straight whiskey during aging in a freshly charred oak barrel. Caramel, on the other hand, imparts only 5-hydroxymethyl-2-furaldehyde. Thus, the measurement of the concentrations of furfural and 5-hydroxymethyl-2-furaldehyde and their ratio could effectively authenticate the standard of identity of straight whiskeys. This study shows that straight whiskeys aged in freshly charred oak barrels for a period of 2 years or more have a 2:1 or higher ratio of furfural to 5-hydroxymethyl-2-furaldehyde. A high-performance liquid chromatographic method for the determination of furfural and 5-hyroxy- methyl-2-furaldehyde at low parts-per-million levels is described.

Through-container, extremely low concentration detection of multiple chemical markers of counterfeit alcohol using a handheld SORS device

“…Strategies for the authentication of certain spirit categories have been reported in the literature 6 – 8 . With standard analytical measurement employed for the authentication of spirit drinks including: measurement of alcohol strength 4 ; gas-chromatographic analysis of various volatile components 9 – 11 ; liquid-chromatographic analyses of sugars, wood components and colouring compounds 7 , 12 and the measurement of stable isotope ratios in order to provide information on either botanical 13 – 15 or geographical 16 origin. Other techniques have also been applied to the discrimination and authentication of spirits, such as: capillary electrophoresis 17 , trace element concentrations 18 ; nuclear magnetic resonance (NMR) spectroscopy 19 , 20 and electrospray ionization mass spectrometry 21 , 22 .…”

Formation of volatile and maturation-related congeners during the aging of sugarcane spirit in oak barrels

“…Furfural and 5‐hydroxymethylfurfural can be present in burned sugarcane, or they can be generated during the distillation process by pyrogenation of the organic matter precipitated at the bottom of the pot still. Moreover, Maillard reactions and caramelization caused by the thermal treatment of wood during the barrel‐making process can also generate these compounds by the thermal breakdown of pentoses and hexoses, and during the aging process they are extracted and incorporated into the beverage .…”

Aromatic profiling of flavor active compounds in sugarcane spirits aged in tropical wooden barrels

“…Wood toasting plays an important role in the formation of these compounds. Nontoasted wood presents only small contents of furfural and furfuryl alcohol (Jaganathan & Dugar, 1999). Each maturation congener shows a different behavior related to oak species and toasting.…”