Material guide · 19
Material guide: gamma-decalactone — the creamy skin of a peach, and a handover of ripening smells
· 17 min read
CAS 706-14-9, the core lactone of peach. A 2010 study measured the handover as fruit ripens: green leaf volatiles step off, lactones step on, and gamma-decalactone is the principal volatile of the late ripening stage. Material labelled natural mostly comes from yeast fermenting castor-oil ricinoleic acid, and a 1998 study found the yeast also eats its own product. 111 suppliers, 256-hour substantivity; a rare base-note citizen of the fruity family.
The cis-3-hexenol guide was about the green of the second the grass is cut. This one is about what happens after the green leaves the stage: the peach ripens, and someone else comes on. What is in a peach and what it takes to make one are two different lists.
What matters
- Gamma-decalactone is the lead of that creamy, waxy peach-skin smell. 256 hours of substantivity make it a rare base-note citizen of the fruity family. Medium strength, easy to work with.
- A ripening peach is a smell handover: the cut-grass crowd of green leaf volatiles steps off, the lactone family steps on. A 2010 study measured that curve.
- Peach lactone labelled "natural" mostly comes from yeast fermenting castor oil. Same molecule as the synthetic; the identity and the price gap live on the specification sheet.
The record
| CAS | 706-14-9 |
| Formula | C₁₀H₁₈O₂ |
| MW | 170.25 |
| Odour | fresh, oily, waxy, peach, coconut, buttery, sweet, fruity, creamy |
| Odour family | fruity |
| Strength | medium |
| Substantivity | 256 h (neat, on a strip) |
| Specific gravity | 0.950–0.955 (25 °C) |
| Flash point | 93 °C |
| Shelf life | 24 months or longer (cool, dark, sealed) |
| Registers | GRAS, JECFA, CoE, FEMA GRAS, IFRA |
Plain reading: CAS is the material's ID number. Fruity materials mostly run fast (cis-3-hexenol lasts 4 hours; banana ester about the same), so 256 hours makes this one the family's odd resident: it carries "peach" all the way into the base. And "coconut" and "buttery" in the descriptors are no distraction; in the lactone family, peach and coconut have always been two faces of one thing.
A handover of ripening
In 2010, Zhang and colleagues tracked peaches (cultivar Yulu) ripening after harvest at 20 °C and measured the aroma compounds through ripening:
Concentrations of n-hexanal, (E)-2-hexenal, (E)-2-hexenol and (Z)-3-hexenol decreased, whereas the production of (Z)-3-hexenyl acetate, γ-hexalactone, γ-octalactone, γ-decalactone and δ-decalactone increased with fruit ripening. Lactones showed a clear pattern concomitant with the climacteric rise in ethylene production, with γ-decalactone being the principal volatile compound at the late ripening stage.
The (Z)-3-hexenol on the falling list is the leaf alcohol of the previous guide. An unripe peach smells of leaves because the green-leaf crowd is still on stage; by full ripeness the lactones have taken over and "peach" properly arrives. When you pick peaches by nose at a fruit stand, you are reading exactly this handover curve.
For formulation you can copy the curve directly: keep more green for an unripe peach, turn the lactones up for one that drips when bitten. Same fruit, two formulas.
The "natural" peach is brewed by yeast
Gamma-decalactone does occur in peaches, but the content is far too low for anyone to extract it from fruit, and the market runs on yeast fermentation instead; both of those are industry common knowledge. The route Pagot and colleagues studied in 1998 is exactly that fermentation: the yeast Yarrowia lipolytica takes ricinoleic acid from castor oil through peroxisomal beta-oxidation into this "peachy aroma compound". They also found something delicate: the yeast both makes and eats gamma-decalactone. Every strain they tested consumed its own product, and yield came down to the balance between synthesis and degradation (the paper concludes that peroxisomal beta-oxidation is involved in the lactone's catabolism too).
The fermented molecule is identical to the chemically synthesised one, but fermentation-route material can be labelled a natural flavouring under most regulatory frameworks, and it costs a tier more. The first time I compared prices I stared at the screen for a moment: same CAS, several times the price. Which one to buy depends on your positioning. A brand running an all-natural line has a reason to pay the premium; for practice and general formulas the synthetic is fine. The judgment from the batch variation article, applied once more.
For what does and does not change when one molecule comes from different processes, see Can fragrance materials be brewed with yeast?.
Smelling it
- Medium strength; a 10% dilution is a comfortable evaluation. Neat it leans oily-waxy, and the peach only steps forward diluted.
- Gamma and delta are two textures of peach: gamma-decalactone sits on the buttery skin side, delta-decalactone is creamier, drifting toward whipped cream and coconut. Smell the pair side by side once and you will know which to reach for.
- Below 1% it retreats from "peach" to "softness". Plenty of florals and white-musk formulas that read nothing like fruit have a low dose of lactone hiding inside.
- With benzyl acetate you have the opening move of a fruity white floral.
The catalogue family
| Item | What it is |
|---|---|
| gamma-undecalactone (119 suppliers) | the eleven-carbon version, trade-named "aldehyde C-14"; sweeter, more apricot |
| gamma-decalactone (111 suppliers) | the material itself: buttery peach skin |
| delta-decalactone (104 suppliers) | the delta version; creamier, more overtly coconut |
| delta-dodecalactone (92 suppliers) | the twelve-carbon delta, a thicker cream |
| gamma-octalactone (92 suppliers) | the eight-carbon version, leaning coconut and caramel |
| gamma-dodecalactone (82 suppliers) | the twelve-carbon gamma; peach drifting toward musky wax |
And one old trap worth defusing: gamma-undecalactone goes by "aldehyde C-14", but it is not an aldehyde. It is a lactone. Industry lore has it that the name is a leftover from perfumery's early numbering habits, and even our database prints "(so-called)" next to it in the catalogue. When you see a "C-14", check the CAS before guessing at the structure.
Regulatory
Listed on GRAS, JECFA, CoE, FEMA GRAS, IFRA. As always, registers carry no limit values. The lactones are regulatorily uncomplicated; for skin formulae, consult the current IFRA Standards and the supplier's specification.
Buying it
- A small bottle each of gamma- and delta-decalactone; smell them side by side before picking your workhorse.
- Read the specification for the "natural" designation and the CAS: fermented and synthetic material share a CAS at very different prices, so know which one you are paying for.
- Medium strength won't bite, but at the 256-hour tier the strip will stay with you for a week.
→ Gamma-decalactone in the database: full properties, supplier list, suggested pairings. → Gamma-undecalactone | Delta-decalactone | Search by odour: try "peach creamy" for its neighbours.
References
B. Zhang, J.-Y. Shen, W.-W. Wei, W.-P. Xi, C.-J. Xu, I. Ferguson & K. Chen, Expression of genes associated with aroma formation derived from the fatty acid pathway during peach fruit ripening, Journal of Agricultural and Food Chemistry, 58(10), 6157–6165 (2010). PMID 20415420
Y. Pagot, A. Le Clainche, J.-M. Nicaud, Y. Waché & J.-M. Belin, Peroxisomal beta-oxidation activities and gamma-decalactone production by the yeast Yarrowia lipolytica, Applied Microbiology and Biotechnology, 49(3), 295–300 (1998). PMID 9581293