The Applications of Magnetic Resonance in Food Science 16-19th July 2006 - University of Nottingham, UK

Dairy yp product authentication by y 1H NMR spectroscopy in combination with different chemometric tools Marion Cuny Eurofins Scientific Analytics, Nantes, FR

www.eurofins.com

Fresh dairy product market In France, in 2003:

ƒConsumption: p 138.8 kg g dairy y products p per p inhabitant. ƒSales: 22%

Desserts Fromages frais

57%

21%

Yoghurts

ƒInnovation: 80 new fresh dairy products entered the market : yoghurts 38 dairy desserts desserts, 10 fromages frais. frais ƒ32 yoghurts, Nottingham, July 2006

2

Fresh dairy product authentication ƒ Increased number of product types on the market : fat-free, full-fat, set, stirred, drinkable, probiotic

ƒ Increased consumption of dairy products ƒ P Possible ibl fraud f d and d mislabelling i l b lli : ƒ Declared fruit content (%) ƒ Addition of undeclared ndeclared compo compounds nds

Æ Need for rapid authentication methods Nottingham, July 2006

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Analytical approaches ƒ Target analyte approach • direct analysis of adulterant or authenticity indicator • comparison of analytical results with expected values obtained on authentic samples • chemical, biological components ƒ Fingerprint/multivariate approach • pattern comparison of authentic and adulterated products ƒ Indirect approach • inference i f off a product’s d t’ authenticity th ti it ffrom iindirect di t comparison i of authentic and adulterated products

Nottingham, July 2006

4

Analytical approaches ƒ Target analyte approach • direct analysis of adulterant or authenticity indicator • compare analytical results with expected values obtained on authentic samples • chemical, biological components ƒ Fingerprint/multivariate approach • pattern comparison of authentic and adulterated products ƒ Indirect approach • inference of a product’s product s authenticity from indirect comparison of authentic and adulterated products

Nottingham, July 2006

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Analytical approaches

ƒ Fingerprint/multivariate approach • pattern comparison of authentic and adulterated products

1H

Nottingham, July 2006

NMR spectroscopy

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Where is the relevant information in the spectrum? p Examples : Aromatic compounds x 10

Sugars

Acids

S p e c tr u m o f a s tr a w b e r r y y o g h u r t

8

2.5

2

1.5

1

0.5

0 10

8

6

4

2

0

c h e m ic a l s h if t ( p p m )

The relevant information may be in the whole spectrum No part of it should be neglected Nottingham, July 2006

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Where is the relevant information in the spectrum? p

Spectrum = around 32000 data points Noisy parts Depending epe d g on o the t e fraud aud Æ Non-informative o o at e zones o es Spectrum contains a lot of non-informative signals. Suppression of variables Selection of relevant information DATA SIZE REDUCTION

Nottingham, July 2006

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What is a variable? Each chemical shift that has a spectral value recorded = a variable

valueinthespectrum

3 5 3,5 3 2,5 2 1,5 1 0,5 0 1

1,05

1,1

1,15

1,2

1,25

ppm

Nottingham, July 2006

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Selecting information In addition to usual methods of variables selection:

ƒ ƒ

suppression of known non-informative variables mean of continuous data points

Application of novel approaches for variable selection using g 3 chemometric methods: ƒ ƒ ƒ

With high variance criterion Clustering Variables approach (CLV) Evolving Window Zone Selection method (EWZV)

Nottingham, July 2006

10

Example of strawberry yoghurt spectrum

?

Nottingham, July 2006

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Example of strawberry yoghurt spectrum a. Samples : 65 retail samples %Fruit content

Group Number

Number of samples

Fruit yoghurt : FR