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F&F Literature Review: Fragrance Release

Contact Author Rachel Grabenhofer, Managing Editor, Cosmetics & Toiletries
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Fragrances and flavors are well-known for their ability to tap into primordial feeling and instincts, so marketers continue the search for new ways to tap into and initiate their powerful influence. It’s no wonder why fragrances and flavors remain as relevant today as ever; as do some of their formulation challenges.

As a search of the latest fragrance research literature reveals, the industry remains focused on improving fragrance duration/release, as well as finding label-friendly natural materials. Interestingly, however, with the advent of genetic research applications, flavor and fragrance preference profiling is now possible. Following is a review of these recent literature findings.

Catch and Release

A recent study published1 in Polymer Bulletin explored the release characteristics of a cross-linked amphiphilic polymethacrylate synthesized with differing degrees of hydrophilicity. The polymethacrylate material included hydrophobic octanal-derived acetal and hydrophilic poly(ethylene glycol) moieties.

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The authors found octanal was released from a dual-phase system of hexane with an aqueous suspension of the polymers. In this acidic solution, the acetal moieties were gradually hydrolyzed, releasing octanal continuously for 600 hr. They noted the observed release increased with increasing hydrophilicity under acidic conditions.1 These observations provide new insight on fragrance release mechanisms.

Hydrophil/phobicity also led the charge in an article published in Detergents, Surfactants, Interface and Colloids. Here, the authors used analyses such as small angle x-ray scattering (SAXS) and electron spin resonance (ESR) to determine how fragrance incorporated into cationic vesicles affected their bilayer structures and membrane-membrane interactions.

Vesicles were prepared from a surfactant composed primarily of di(alkyl fatty ester) quaternary ammonium methosulfate. The fragrance components l-menthol, linalool and d-limonene were infused into the vesicle membranes to model scent-releasing fabric softener.

Analysis of SAXS revealed the more hydrophobic the fragrance component, the more pronounced the increase in surface separation (i.e., water layer thickness). Spin-label ESR also indicated various molecular motions in the surfactant bilayers upon the addition of fragrance components.

Based on overall findings, the authors concluded these techniques demonstrate how fragrance molecules having different hydrophobicity and molecular architectures, when infused into cationic vesicles, affect membrane structures and interactions. They suggest this could prove useful for precisely controlling fragrance release.2

In related delivery work, Firmenich recently submitted a patent on a pro-fragrance precursor to deliver a fragrance from a fabric or textile upon oxidation.3 Specifically disclosed is the use of cinnamyl ether compounds as precursors for the release of fragrant alcohols and aldehydes.

According to the inventors, compounds already exist to deliver fragrance upon hydrolysis or exposure to light. However, solutions to initiate and control the release of a fragrance upon exposure to ambient oxygen are also desired. As such, the oxidizable pro-fragrances disclosed herein were developed to deliver fragrance over a prolonged period of time after exposure to air.3

Nature Calls

Nature continues as a source for inspiration and innovation in flavor and fragrance (F&F) development. More recently, work in this segment has turned to biotechnology as a means to derive chemistries from nature in such a way as to maintain their natural additive label status.

For example, work published4 in the Journal of Chemistry Technology & Biotechnology explored how F&F can be developed via microbiological hosts—with a special consideration for in situ product removal strategies. These are desired because many F&F compounds are cytotoxic toward common microbiota.

These authors used thermodynamic principles and experiments to determine partitioning coefficients, which in turn could differentiate between phases having high and low thermodynamic affinity toward 17 key F&F compounds. As such, the appropriate extractants for several F&F compounds could be identified, providing researchers working in the booming sector of microbial F&F production with a useful tool to optimize processes.4

Following along a different natural path, researchers from AmorePacific have submitted a new patent application for blends of fragrance materials that reproduce the aroma of certain citrus flowers.5 According to the inventors, this is achieved by adding, respectively, jasmone and β-caryophyllene to linalool, myrcene, nerolidol, methyl anthranilate or the like—as these have been identified as aromatic components of the flowers of both Citrus unshin and Citrus natsudaidai; and by adding γ-terpinene to linalool, myrcene, geraniol, β-ocimene or the like—aromatic components of the flowers of Citrus sudachi.

Furthermore, citrus aroma is rendered by adding α-farnesene to β-ocimene, 6-methyl-5-hepten-2-one, anthranilaldehyde, limonene, methyl anthranilate or the like, which are aromatic components of the flowers of Citrus japonica. The inventors found the resulting fragrance compositions to be outstandingly palatable and to reproduce the inherent aromas of Citrus unshin, Citrus natsudaidai, Citrus sudachi and Citrus japonica.5

Genetic Disposition to F&F Preferences

Finally, a new patent application from Exploragen Inc.6 looks to our very DNA for answers about F&F preferences. Disclosed here is a method using genetic profiling to predict an individual’s taste and/or scent choices for gustative or olfactive products.

Interestingly, however, with the advent of genetic research applications, flavor and fragrance preference profiling is now possible.

The method was developed by obtaining a biological sample, such as saliva, from subjects containing their nucleic acids and analyzing genotypes based on single nucleotide polymorphisms (SNPs). In addition, taste and/or scent preference scores of gustative and/or olfactive products were collected from subjects.

Taken together, the inventors identified specific SNPs (disclosed in the patent) that serve as genetic markers for specific taste and/or scent preferences. The patent also disclosed tests demonstrating the accuracy of this technique; for example, pairing subjects with wine flavors. These results showed the method successfully predicted consumer preferences.

 

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References

References

  1. H Morinaga, H Morikawa and T Endo, Controlled release of fragrance with cross-linked polymers: Synthesis and hydrolytic property of cross-linked amphiphilic copolymers bearing octanal-derived acetal moieties, Polymer Bulletin 75(1) (Jan 2018) pp 197-2017
  2. T Ogura, T Sato, M Abe and T Okano, Small angle x-ray scattering and electron spin resonance spectroscopy study on fragrance infused cationic vesicles modeling scent-releasing fabric softeners, Detergents, Surfactants, Interface and Colloid 67(2) (2018) pp 177-186
  3. US Pat App US20180016521A1, Pro-fragrance compounds, assigned to Firmenich SA, available at https://patents.google.com/patent/US20180016521A1/en (Jan 18, 2018)
  4. X Priebe and AJ Daugulis, Thermodynamic affinity-based considerations for the rational selection of biphasic systems for microbial flavor and fragrance production, J Chem Tech & Biotech 93(3) (Nov 28, 2017)
  5. US Pat App US20180030375A1, Fragrance composition reproducing the aroma of citrus flowers, assigned to AmorePacific Corp, available at https://patents.google.com/patent/US20180030375A1/en (Feb 1, 2018)
  6. US Pat App US20180057866A1, Genetic profiling methods for prediction of taste and scent preferences and gustative and olfactive product selection, Exploragen Inc., available at https://patents.google.com/patent/US20180057866A1/en (Mar 1, 2018)

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