Benzaldehyde’s odor and taste are so unique and basic that it, in itself, forms an organoleptic class--benzaldehyde. The odor has a pleasant, sweet, aromatic note and the taste the same, with a slight, sweet, aromatic bite. We recall almonds, marzipan, peach pit meat (what youngster didn’t chew a peach pit nut?) and pistachio ice cream.
The industrial cliche for the product is “Bitter Oil of Almonds,” a name which has been misleadingly applied to the synthetic product since it emerged from tbe chemist’s flask before the year 1900. Small amounts of synthetic benzaldehyde produced from benzal chloride first appeared on the market as natural oil of bitter almonds about 1890, Since the price ratio between the natural product and the synthetic is significant (currently 100 to 1), the perfumer. flavorist and chemist have been constantly devising methods to differentiate the fraudulent product from the real thing.
The earliest detection methods utilized the precipitation of silver chloride by contacting the aqueous burned residues of benzaldehyde with silver nitrate reagent. Subsequent methods developed for use by both the US Pharmacopoeia and the Food Chemical Codex employ the visible green-blue color induced in a bunsen burner flame by a copper screen which has been dosed with the product. As industry moved away from the commercial production of benzaldehyde from benzal chloride to direct oxidation of toluene, which yields a product free of chlorine, fraud detection required advanced techniques. At first, carbon-14 isotope analysis was successful in detecting synthetic aldehyde being offered as natural. However, the price differential of $1.00/lb for synthetic versus $100.00/lb for natural benzaldehyde prompted tbe spiking of the synthetic product with carbon-14 rich material. thus cloaking its nature. Carbon-13/carbon-12 ratios (13C/12C) proved ambiguous. The most recent successful method is deuterium/hydrogen isotope rations. One might say that the crooks are encouraging the advancement of science.