Carbohydrate and nitrogenated compounds in liquid smoke flavorings.

Commercial smoke flavorings were extracted with dichloromethane and the remaining aqueous phase was evaporated at room temperature; the residues obtained were dissolved in methanol and studied by gas chromatography/mass spectrometry. The composition of these residues was totally different from that of the dichloromethane extracts, constituting a small number of compounds that were also detected in the dichloromethane extract, as well as a large number of compounds not described before as components of either smoke for food smoking or smoke flavorings. Among those compounds not previously described there are some furan, pyran, and phenolic derivatives, as well as some pyridine and carbohydrate derivatives. The main component of these fractions is 1,6-anhydro-beta-D-glucopyranose, or levoglucosan. Likewise, aqueous residues of liquid smoke flavorings, prepared at a laboratory scale from beech, vine shoots, thyme, and sage, were studied in the same way. These contained compounds of the same groups cited above, but showed clear differences. The aqueous residue of beech smoke flavoring was the most similar to that of the commercial smoke flavorings. The aqueous residues of vine shoots, thyme, and sage smoke flavorings contained a lower number of furan, pyran, and carbohydrate derivatives and a higher number of nitrogenated derivatives. Instead of levoglucosan, the main component was an unidentified compound, present in all samples, included in the carbohydrate derivatives group. In the samples studied, the influence of the vegetal source on the composition of the aqueous fraction has been shown. In the future, attention must be paid to the functionality of these smoke components.