Sample preparation is critical to successfully analyse odorants (odour active volatile organic compounds). However, there is no one perfect sample preparation method for the complete, holistic extraction of odorants. Is it possible to use a representative test mixture of odorants to measure, compare and predict the ability of different sample preparation methods?

1. Perfect Sample Preparation – is Complete and Holistic
Extraction of Odorants from Foods Possible?
Proprietary information: Not to be reproduced or distributed without the express consent of Mars Inc. ©Mars 2016
Introduction
Sample preparation is critical to successfully analyse odorants (odour active
volatile organic compounds). However, there is no one perfect sample
preparation method for the complete, holistic extraction of odorants. Why?
Table 1. Odorants are diverse in; chemical function, physicochemical properties,
odour threshold and reactivity and food matrices are complex.
Is it possible to use a representative test mixture of odorants to measure,
compare and predict the ability of different sample preparation methods?
No. Name BP. (˚C) Kow Odour Threshold (µg / kg)
1 trimethylamine 3 1.10 25 (pH = 7.9)
2 2-methyl-3-furanthiol 58 398 7.0 x 10-3
3 bis(2-methyl-3-furfuryl)disulfide 280 13800 2.0 x 10-5
1Mars Petcare, WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Leicestershire, UK.
2University of Nottingham, University Park, Nottingham, UK.
3Anatune, Wellbrook Court, Cambridge, Cambridgeshire, UK.
LEWIS L. JONES1, Samuel Wordsworth2, Nathan Hawkins3, Kathy Ridgway3, James B. Addision1.
O
SH
Results
Figure 4. Extraction Efficiency. Neither sample preparation method (SPME or
SAFE) extracted completely and holistically across the full physicochemical
landscape assessed. Matrix fat composition has a large effect on extraction
efficiency (mean values shown, n = 8).
Figure 4. Predicting Extraction Efficiency The results can be used to predict
the extraction efficiency of odorants from their LogP and Log Vp values, which
are available from on-line databases e.g. Estimation Programs Interface Suite™
Methodology
The extraction efficiencies of a representative test mixture of 23 compounds from
3 model systems were calculated for 2 sample preparation methods. The methods
chosen were complementary:
• extraction based on volatility: headspace extraction by solid phase
microextraction (SPME)
• Extraction based on polarity: liquid extraction – distillation by solvent assisted
flavour evaporation (SAFE).
The model systems for extraction of the test mixture were water, 10% fat in water
and 100% fat.
Extraction efficiency (%) =
Test mixture Extract
Model
Figure 2. Sample preparation by liquid extraction – distillation using solvent
assisted flavour evaporation
Peak Area Extract
Peak Area Test Mixture
x 100
1.00E-12
1.00E-10
1.00E-08
1.00E-06
1.00E-04
1.00E-02
1.00E+00
1.00E+02
1.00E+04
-10 -5 0 5 10
Odorants Test Mixture
Hydrophobicity (log P)
Volatility(logVp)pL)
Very volatile
Less volatile
Hydrophilic Hydrophobic
Figure 1. A representative test mixture of stable odorants was selected over a
broad landscape of physicochemical properties within the area appropriate for
GC analysis.
heat
1 2 3
Conclusion
It is possible to measure and compare the extraction efficiency of different
sample preparation methods, using a representative test mixture of stable
odorants, selected over a broad landscape of physicochemical properties.
Both methods assessed were unable to extract fully across the physicochemical
landscape occupied by odorants, in any of the 3 matrices. Despite choosing
complementary methods, areas of the landscape remain inefficiently extracted
by both methods. In particular, the very volatile, hydrophilic odorants.
The use of a representative test mixture, the fundamental knowledge produced
and subsequent modelling enables:
• Optimisation of sample preparation methods
• Development of new methods to cover a broader landscape or focus on
specific areas e.g., very volatile, hydrophilic compounds
• Estimation of extraction efficiency for targeted analysis – given knowledge of
an odorants hydrophobicity (Log P) and volatility (log Vp), which is widely
available online.
Further work is required to: (i) test the model and (ii) investigate odorant stability
on extraction efficiency.
References
CAS Number
Properties
Estimated
extraction
efficiency
• Reineccius, G., (2005) In: Flavor chemistry and technology, second edition; CRC Press: p.
33-72.
• Belitz, H.-D., et al. (2000). Food Chemistry. Berlin, Springer.
• Linforth, R (2009) compilation of odorant physicochemical properties, unpublished.
• US EPA. (2016). Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.1, United
States Environmental Protection Agency, Washington, DC, USA
100% Water 10% Fat 100% Fat
SPME
SAFE
Log P
LogVP
LogVP
Log P
LogVP
100
80
60
40
20
0
80
60
40
20
0
60
40
20
0
2
1
0
-1
-2
-3
-4
0-1 1 2 3 4 5 6
2
1
0
-1
-2
-3
-4
0-1 1 2 3 4 5 6
Log P
LogVP
2
1
0
-1
-2
-3
-4
0-1 1 2 3 4 5 6
2
1
0
-1
-2
-3
-4
Log P
0-1 1 2 3 4 5 6
Log P
0-1 1 2 3 4 5 6
LogVP
2
1
0
-1
-2
-3
-4
Log P
0-1 1 2 3 4 5 6
LogVP
2
1
0
-1
-2
-3
-4
0.6
0.4
0.2
0
0.6
0.4
0.2
0
0.8
6
4
2
0
8