Aromatic plants: from extraction

to analysisThierry TALOU

Agro-industrial Chemistry LaboratoryNational Polytechnic Institute of Toulouse

ENSIACET 4 allée Emile Monso 31432 Toulouse

Olfactory system

Olfactory system

Olfactory system

Base Materials

ζ Aromatic plants

ψFlowers, fruits, herbs, spices, roots, seeds, wood, leaves, …

Extraction of aromatic compounds

ζ Methods for extraction of organic odorous compounds are based on 2 physico-chemical properties of aromatic molecules:

– low polarity

– high volatitily

Main extraction methods

ζ Volatility: methods based on HeadSpace or on vacuum distillation

ζ Polarity: methods based on solvent extraction

ζ Volatility & Polarity : methods based on steam distillation ou Simultaneous Distillation-Extraction

ζ Maceration / »Enfleurage »

ζ Cold expression

ζ Hydrodistillation/fractionnation

ζ Extraction by volatile solvents

ζ HeadSpace extraction

ψStatic headspace (SPME)

ψDynamic headspace (trapping)

Main extraction methods

Main extraction methods

Hot Maceration

Old process for flowers not producing perfume AFTER pickling

RoseOrange flower

Absolute of pomade

JasmineTubéreuse

Cold « Enfleurage »

Absolute of pomade

Flowers supporting badly heating and keeeping their perfume AFTER pickling

Cold Expression

ζ This process is ONLY applied to citrus familly (lemon, orange,…)

Hydrodistillation : method based on steam distillation

Alambic

Could be used on the differents parts of plants resisting to heating

Principle :

Hydrodistillation is based on evaporation followed by condensation of liquids

Essencier

Florentin flask

Extraction by volatile solvents

Vegetable Matter

Extractor

Washing with solvent(hexan)

Decantor / Concentrator

Partial Distillation

For plants sensible to heating AND giving consequent extraction yields

Resinoïd : from processing of dry plants

Absolute : resinoid or concrete washed several

times with ethanol and cold filtered

Concrete : from processing of fresh plants

Odorous molecules, waxes and

dyes

Solvent to re-use

Trapping of leaving flower odor by using HeadSpace technique

Static HeadSpace analysis

ζ Solid Phase Micro Extraction (SPME)

ψ adsorption of headspace volatiles at the surface of the fiber

ψ Direct injection on a classical GC injector

Problems :Variability between fibers Life time: 50 desorptions

Fiber support

Vial

Fiber

Sample (liquid or solid)

HeadSpace

Fiber characteristics:-PDMS (polydimethylsiloxane) : general use-CAR/PDMS (Carboxen/polydimethylsiloxane) : traces analysis - CW/DVB (Carbowax/divinylbenzene) : polar compounds analysis

Stationary phase

Silica Fiber

Analysis of components

ζ Gas Chromatography (GC-FID) ξ Obtention of aromatic profiles (Finger Print)ξ Pre-Identification by using Kovats Index or Retention Index determined on polar AND

ξ Quantification by intern standart method

ζ High Pressure Liquid Chromatography (HPLC)ξ Example:Titration of piperine in pepper

Analysis of components

Typical GC profile of Essential Oil

ζ Gas chromatography coupled to mass spectrometry ψ Identification: comparison of mass spectra obtained with data bank

ψ Various ionization modes: Electronic Impact, Chemical Ionization

ζ Chiral chromatography (mono or bi-dimensionnal) - FIDψ Determination of the naturality of chiral compounds ONLY

(enantiomers have NOT the same odor: carvone, menthol,..)

ζ Gas chromatography coupled to isotopic mass spectrometryψ Determination of the naturality of ALL components

Identification & Authentification

Gas Chromatography coupled to Olfactometry: GC-O

ζ Gas chromatography coupled to olfactometry is a technique presently widely used in aromatic industry which couple instrumental analysis to sensory analysis.

ζ The sniffing consists to identify the odor associated to the peaks during the chromatographic separation

ζ The objective is to determine the key odor compounds of an aromatic extract by providing either qualitative (descriptive) nor quantitative (scaled) sensorial data

What is the interest to « sniff » odors at the end of the GC column?

ζ Volatility # odorous activity

ζ Human nose is more sensible than GC detector

ζ The odor human thresholds are VERY different to the instrumental detection thresholds : factor 1010 from one compound to another.

ζ All the identified compounds by instrumental methods do not contribute identically to the overall odor of the product

Gas Chromatography coupled to Olfactometry (sniffing)

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fruity

1 - Aromatic extract2 - Chromatograph3 - Sniffing Port4 - Panelist5 - Computer6 - Voice Recorder

ChromatogramGC-FID

Aromagram ofdetected compounds at the sniffing port

Odors descriptors

ζ Classification of perfumes (CFP)

ζ The Field of Odors (J.N. Jaubert 1984)

ζ Data base of T.E. Acree (www.nysaes.cornell.edu/flavornet)

ζ Descriptors of Aldrich

ζ Descriptors of Firmenich

ζ Reference Book of S. Arctander (ISBN 0-931710-38-3)

ζ Lexicon of G.V. Civille et B.G. Lyon (ISBN 0-8031-2072-9)

ζ AFNOR standards (définition of vocabulary for sensorial analysis)

Odors descriptors

Odors descriptors

After the mandatory analytical step, the flavorist or the « NEZ » has now

informations on the hundreds of molecules identified in the plant and to be used for formulating the

corresponding flavoring Formulation

MUSTDetermine

these factors

Do synergic effects exist?

What are their REAL ratios?

The key flavor compounds are chemically and

sensorially identified

Formulation ?

« Tous les chemins mènent... Arôme », P.Duby & E.Bôlcs, FIS.

Formulation by using the Perfume Organ

ζ Essential Oilsζ Aromatic Extractsζ Synthetic Molecules

After selecting among hundreds of compounds the genuine odors, their association in precise ratios is the key factor for designing the best flavoring or perfume.

« Note », « accords »,« nuances », « palet »,

« organ »of base materials

Analogy with painting and music