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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)
1
2
3 4
5
6
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