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The chemistry of Peach

Giuseppe Coglienti

THE HISTORY OF PEACH AROMA FORMULATION

Peaches have different aromas depending on cultivars.

To a certain extent they can be unified and in practice, this criteria has been adhered to in the imitation and formulation.

An older formulation involved for the use of the following constituents in appropriate doses.

  • Bitter Almond Oil

  • Sweet Orange Oil

  • Bitter Orange Oil

  • Carnation Oil

  • Neroli Oil

  • Bay St. Thomas Oil

  • Cinnamon Oil

  • Coriander Oil

  • Anethol

  • Ethyl and Methyl Cinnamate

This product according to the intentions of the manufacturer was designed more for the liquor industry than for the confectionery industry.

In comparison, a simple mixture of C14 Aldehyde (Gamma-undecalactone) with small amounts of Amyl Acetate and Ethyl Butyrate formed that peach base for confectionery that has long been baited.

A compromise between one and the other formula was represented by the following:

  • Amyl Butyrate

  • Ethyl Nitrate

  • Ethyl Caprylate

  • Ethyl Phenylacetate

  • Aldehyde C14

  • Rose Oil

  • Sweet Orange Oil

  • Bitter Almond Oil

Or from this other: Benzoic Aldehyde, Ethyl Butyrate, Gamma Undecalactone (Aldehyde C14), Ethyl Acetate, Amyl Acetate, Amyl Butyrate, Amyl Valerianate, Sweet Orange, and Lemon Oils, Enanthic Ether, Ethyl Cinnamate, Ethyl Vanillin, Ceylon Cinnamon and allspice oils, Ethyl Phenyl Acetate, Clary Sage oil.

Years later one step further was made this other type of combination:

Mid-modern Times

Bearing in mind that the formulators of the aforementioned mixtures had nothing at their disposal but the few raw materials of the time and their skills in organoleptic evaluation, since the few studies on the constitution were negligible, we can only note that at the beginning beyond this level of imitation it was not so easy to get there.

Everything was centered on flowering, spicing, fruiting, and sweetening the note of the Benzoic Aldehyde, which according to what we will later say was practically the only constituent exactly identified in the natural complex, and this was also accomplished by using products that were not exactly congenial as in the case of ethyl and Methyl Cinnamates, endowed with a honeyed or fruity (Raspberry) note, respectively, or in giving an ethereal cue to the C14 Aldehyde that came on the market as a panacea to simplify things.

Peach flavour in beverages

Regardless, however, of the fidelity of imitation simply by looking at the list of constituents chosen in the various formulas, we can see that the criteria of using Citrus notes in large quantities in liqueur-making, decreases their percentage in the presence of unstable esters as much as the aroma was intended for hot processing, and even using for the latter purpose a lactone with a minimum percentage of esters obeyed exactly those rules of chemical-physical compatibility between aroma constituents and between aroma and foodstuff that underlie functional formulation.

Among the flavoring substances reported so far, only one, Gamma-undecalactone, in addition to the background aroma of Benzoic Aldehyde, has an aroma that well resembles that of Peach while the others can only be considered as side notes made more harmonious by the presence of essential oils or even Vanillin.

Additional Synthetics ingredients for Peach aroma

We now point out some products that would not clash in peach-note compositions as we feel them close to that aroma.

Some are constituents of other natural flavorings:

Others have not yet been identified in nature, although their presence is highly probable:

  • Propyl Cinnamate

  • Phenyl Ethyl Cinnamate

  • Amyl Phenyl Acetate

  • Benzyl Propionate

  • Phenyl Salicylate.

Finally, others are synthetic such as Allyl Cyclohexyl Valerianate, Allyl Cyclohexyl Caproate, Methyl Octincarbonate, and Phenyl Allyl Alcohol.

All these products can be used for the formulation of “Peach” notes. Some succeed better in confectionery while others in liqueur-making but their use (I am referring to unproven natural constituents and synthetics) is not allowed in Italy.

These very high-yielding products have very low prices and can normally be prepared at titers of not less than 95-97%.

With the Gas-chromatographic study conducted with the assistance of other instrumental techniques on the aroma of the "Red Globe" Peach, it was confirmed that not all peaches have the same constituents and in any case not in the same percentage ratios, which made us aware of the presence of these constituents that I list according to their retention time:

  • Acetaldehyde

  • Methyl Acetate

  • Ethyl Acetate

  • Ethyl Alcohol

  • Hexyl Formate

  • Hexyl Acetate

  • Trans-2-Hexen-1-ol

  • Benzoic Aldehyde

  • Isovaleric Acid

  • Ethyl Benzoate

  • Gamma-hexalactone

Examining this list, which would become more apparent by looking at the Gas-chromatogram, we see that nature has in practice combined with a less volatile basic nucleus consisting of the: Gamma-Lactones from Hexa to Deca to the Benzoic Aldehyde, mellowed its volatility with the first constituents, already listed in the majority esters, whose specific aroma is not, however, in the peach note, modified its flavor with acids, and flowered its fragrance with aromatics, Benzoates, Benzyl esters and Benzyl Alcohol.

It would now seem simple to reconstruct the aroma of the Peach; in practice, however, it is still difficult because of those many complications, which we have already mentioned elsewhere in a general way.