An HPLC method is described for the detection of caramel color by measuring the level of 5-(hydroxymethyl)-2-furaldehyde (5-HMF). For the several products of caramelization examined, 5-HMF was the most sensitive indicator of the presence of caramel. The method specifies a reverse phase C18 column, a UV detector set at 277 nm, and a methanol-water gradient to separate 5-HMF from interfering substances. Other flavor compounds resolved by the same gradient are vanillin, ethyl vanillin, coumarin, benzaldehyde, caffeine, anethole, theobromine, and cinnamaldehyde.
Samples containing ethanol are fractionated on a column so that the resultant ethanol content is >93%. Determination of 14C by liquid scintillation counting on the ethanol fraction differentiates ethanol produced by fermentation from synthetic ethanol produced from fossil fuel sources. Twenty-seven samples were fractionated and analyzed for the 14C isotope. Six samples were synthetic ethanol derived from ethylene gas (direct and indirect process), and yielded a mean value for 14C isotope of 0.167 dpm/g carbon with a standard deviation (SD) of 0.066 dpm/g carbon (disintegrations per minute per gram of carbon). The remaining samples were ethanol derived from the fermentation of natural materials, such as corn, pear, sugar cane, grape, cherry, and blackberry, and yielded a mean value for 14C isotope of 16.11 dpm/g carbon with an SD of 1.27. The 14C values for specific mixtures of a synthetic and a natural ethanol compare favorably with the analytical values obtained by this procedure.
A method is described for isolating vanillin from vanilla extract, followed by stable isotope ratio analysis to determine the amount of natural vanillin contained in adulterated vanilla extracts. After the potassium content is determined, the percent Madagascar and/or Java vanilla beans incorporated into the extract may then be approximated from the vanillin/ potassium ratio.
Sake samples are fractionally distilled so that the resultant ethanol concentration of the distillate is approximately 95%. Determination of 14C by liquid scintillation counting on the ethanol fraction differentiates alcohol produced by fermentation from synthetic ethanol produced from fossil fuel sources. 13C/12C stable isotope ratio analysis (SIRA) is capable of detecting alcohol from a cane or corn source in sake samples. This analysis also shows the addition of corn or cane sugar before or after fermentation of the sake.
High pressure liquid chromatography (HPLC) was used to resolve FD&C Blue No. 1 (Brilliant Blue), FD&C Blue No. 2 (Indigotine), Amaranth (formerly certified as FD&C Red No. 2 ) , FD&C Red No. 3 (Erythrosine), FD&C Red No. 4, FD&C Red No. 40, FD&C Yellow No. 5 (Tartrazine), FD&C Yellow No. 6 (Sunset Yellow FCF), and FD&C Green No. 3 (Fast Green FCF). These synthetic acid fast dyes as found in wine and flavor samples were extracted with wool yarn and analyzed by HPLC and thin layer chromatography. The 2 methods are compared for sensitivity and resolution. The HPLC procedure is a quicker way to screen a larger number of samples for artificial colors with better resolution than that obtained by thin layer chromatography. HPLC can separate FD&C Red No. 40 from FD&C Red No. 4 and this could not be achieved by using the described TLC solvent system. The FD&C dyes most commonly found in flavors and distilled spirits were FD&C Red No. 40, FD&C Yellow No. 5, and FD&C Yellow No. 6.
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