|Caramels from DD Williamson. 570 is their most used spirit caramel.|
|Caramel samples from Sethness. Typical spirit caramel is 0.075-0.110|
Most producers give caramel colors a two year shelf stability guarantee, if stored in room temperature and protected from sunlight. Sunlight fades the caramel colors rapidly, in matter of weeks to months. E150a is the most resistant to fading and it fades evenly in all wavelenghts, as E150d usually fades more of the higher wavelenghts (red fades first).
|Loch Dhu, mit farbstoff|
The majority of single malts and virtually all the blends are coloured with E150a. According to The Scotch Whisky Regulation in 2009 only "plain caramel" (E150a) is allowed, although the EU laws permit the use of "spirit caramel", which is not exactly defined in law and can be any E150 and so at least some E150b and E150d could have been used in Scotch whiskies.
|Toasting a barrel (vinography.com)|
Due to the variety of raw materials and additives, the chemical structures of caramels are complex and there are lots of variations even between caramels of the same subgroup. In the production the main reaction is dehydration as water (hydrogen and oxygen) is extracted (boiled) out of the sugars. This results first to sugar monomers as polysaccharides (for example sucrose) are divided into glucose, fructose, galactose, xylose and maltose. As the heating continues, the monosaccharides lose water and react with each other producing big polymers, mainly caramelans (C24H36O18), caramelens (C36H50O25) and caramelins (C125H188O80), which give the caramel most of its color. Additionally some residue sugar may be left in the product and several flavour components are produced, for example different furans, diacetyl, maltol, esters and lactones. Furans are probably the most influential flavour components in most caramels, they are formed especially from fructose or sucrose (containing fructose) in acidic encironment. They also form during the toasting of oak barrels, but the relative amounts of different furans are different as the raw material are either lignin and (hemi)cellulose in oak or simple sugars in caramel. Caramellisation of simple sugars produce less furfural (almond, walnut, grainy) and more 5-hydroxymethylfurfural (butter, musty, waxy, caramel) than caramellisation of oak (there are also significant differences between different oak species, see previous blogs). 5-HMF is not produced if sulphites or ammonium are used in the process (E150b or E150d), but is formed in large quantities in the plain caramel (E150a). 5-HMF is also used as a flavour enhancer in milkpowders, honey, juices and even cigars. Furfural acts as a reactant with various compounds in the spirit; it has some antioxidative properties that slow the oxidation reactions and help to stabilize the color from antocyanins (in especially wine), it also reacts easily with H2S (rotten eggs, nasty sulphur) producing furfurylthiol (strong coffee), decreases the volatile sulphur compund concentrations and potentiates the odor of oaklactone (vanilla,coconut). Some other furans such as hydroxyacetylfuran (sweet), hydroxydimethylfuranone (also known as furaneol, additive in baked bread, coffee and chocolate) and dihydroxydimethylfuranone are also produced. Diacetyl imparts a buttery (butterscotch) flavour and maltol (aka E636) gives freshly baked bread aromas. Esters and lactones (here from sugar, not oak) are usually fruity. Also increased levels of E2-nonenal (cardboard, stale beer) and less hop flavour are also found in caramel coloured beers, but this possibly results from changes in fermentation process and is not studied properly in spirits.
So, caramel does affect the flavour and it is not inert in whisky, but are the quantities used in Scotch whisky industry enough to affect the overall flavour significantly? No reliable scientific fact exists, but my guess is that they probably are significant. Does caramel impair the flavour? It could, but then again in some cases caramel might even improve the taste.
References and further reading:
Abalos D et al. The use of furfural as a metabolic inhibitor for reducing the alcohol content of model wines. Eur Food Res Tech 2011;232;663-669
Blanchard L et al. Formation of furfurylthiol exhibiting a strong coffee aroma during oak barrel fermentation from furfural released by toasted staves. J Agric Food Chem 2001;49;4833-4835
Boscolo M et al. Spectrophotometric determination of caramel content in spirits aged in oak casks. J AOAC Int 2002;85;3;744-750
European Union Directive 95/45
Furukawa Suarez A et al. Impact of colour adjustment on flavour stability of pale lager beers with a range of distinct colouring agents. Food Chem 2011;125;850-859
Laws DRJ, Peppard TL. The stability of flavour constituents in alcoholic beverages. Food Chem 1982;9;131-146
Quesada Granados J et al. Influence of aging factors on the furanic aldehyde contents of matured brandies: aging markers. J Agric Food Chem 1996;44;1378-1381
Ratsimba V et al. Qualitative and quantitative evaluation of mono- and disaccharides in D-fructose, D-glucose and sucrose caramels by gas-liquid chromatography-mass spectrometry di-D-fructose dianhydrides as traces of caramel authenticity. J Chrom A 1999;844;283-293
Rodriguez Dodero MC et al. Phenolic compounds and furanic derivatives in the characterization and quality control of brandy de Jerez. J Agric Food Chem 2010;58;990;997
Scotch Whisky Regulations. Scotch Whisky Association 2009.
Sousa A et al. Isolation and structural characterization of antocyanin-furfuryl pigments. J Agric Food Chem 2010;58;5664-5669
Tsai PJ et al. Interactive role of color and antioxidant capacity in caramels. Food Res Int 2009;42;380-386
www.caramel.com (DD Williamson)