atypiques test de conformité de produits fileeveryone involved with food/feed, from the farmer to...
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Détection de spectres anormaux \ atypiques test de conformité de produitsJuan Antonio Fernández PiernaVincent Baeten & Pierre Dardenne*Walloon Agricultural Research Centre (CRA-W)Gembloux, Belgium* Ex CRA-W member
j.fernandez@cra.wallonie.bev.baeten@cra.wallonie.be
EXPERTISES
Calibration Instrument network
ISO17025&
ISO17043
Interlaboratorystudy
Training
Spectral band interpretation
Homogeneitystudy
Chemometrics
Sampling
Samplepresentation
Standardisation
Data bases
Food and Feed Quality Unit
Ensuring an acceptable level of food/feed quality and safety isnecessary to provide adequate protection for consumers and tofacilitate trade.
This can be achieved by implementing and monitoring qualityassurance measures along the entire food/feed chain - from thereceipt of the raw materials (primary products and otheringredients) to the shipping and marketing of the final productsto the consumers - when it is appropriate and when it is possible.Everyone involved with food/feed, from the farmer to theconsumer, shares in the responsibilities to keep the food/feedsupply safe by taking the necessary precautions to keep food/feedprotected from hazards that can increase human/animal health risks.
The contextQuality control and assurance
In developing countries, the Agrofood/feedindustry is in the process of rapid integration.Medium and large scale groups are expandingproduction capacities
Food and feed industries need todistinguish themselves by suppling afinal quality product. For this, qualitycontrol analysis should be performed,not only in the final product but,mainly at the entrance of theproduction chain when the rawmaterial reaches the industry.
More serious competition!
The contextIndustry
Spectroscopy
Ana
lytic
al M
etho
d
Process control
The contextNeed of rapid methods
The contextVibrational Spectroscopy
1200 1400 1600 1800 2000 2200 24000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
wavelength (nm)
log
(1/R
)
soyabean mealFull fat soyaSoya hulls
Regression equations
Local Window
PCA
GHsimilarity
Several criteria
Protein
Fat
The aimNIR analysis & chemometrics procedure
PLS models
Protein
Fat
Regression equations
ProcedureNIR analysis & chemometrics
Soybean meal models from
Haaland & Thomas, 1988
The Global H (GH) criteria is a modification of the Mahalanobisdistance of each sample from the average spectrum. This distancetakes into account the correlation of the data set.
GH
Mahalanobis
Euclidean
ProcedureNIR analysis & chemometrics
GH value < 3 will guaranteehomogeneous spectra
GH value > 3 will guarantee thatthe spectra are a result of randomchance and hence are most likelyto have outliers
Local Window Principal Component Analysis (LWPCA)Local Window
PCA
ProcedureNIR analysis & chemometrics
ProcedureLocal discrimination modelling
Residuals are used to build thresholds to be applied to theresiduals of the samples to be predicted.
Residual plots
ProcedureNIR analysis & chemometrics
Study case 1Feed contamination
Contamination by microorganism and animal by-products (salmonella, animal proteins…)
Contamination by persistent organic pollutants and toxicmetals (melamine, dioxins, brominated flame retardants…)
Natural toxins in animal feed (mycotoxins, plant toxins…)
Veterinary medicinal products in feeds (antibiotics, …)
Risks from emerging technologies (GM crops, biofuel and food industry by-products…)
Study case 1Feed contamination
Study case 1Feed contamination
The aim of this work is to propose a procedure based on NearInfrared (NIR) spectroscopy and Chemometrics in order tocharacterize a typical feed product (soybean meal) as well as todetect the presence of any possible contaminant.
Laboratory level• Melamine• Whey
Feed plant level• Whey
Study case 1Feed contamination
NIR/NIR Hyperspectral imaging and chemometricsmake it possible to compare efficiently suspectedspectra of new samples and detect melamine in feed.
Melamine
Soybean meal non contaminated
Soybean meal contaminated with 5%
melamine
Rapid detection of any modification
by non-authorized additives likeMelamine
Study case 1Melamine in soybean meal
No false positives
Lab level - whey
No false positives
Study case 1Feed contamination
Lab level - whey
Study case 1Feed contamination
Extension to feed millsStudy case 1Feed contamination
STEP 1Loading of 5 Tons
of Soya bean directly from the
truck
STEP 2Loading of 5 Tons
of Soya bean from the truck
contaminated by simulating a local
contamination
STEP 3Loading of 5 Tons
of Soya bean directly from the
truck
STEP 4Loading of 5 Tons
of Soya bean from the truck
contaminated by mixing
STEP 5Emptying of the
truck. No deliberate
pollution done
Feed mill contamination
Study case 1Feed contamination
Protein Fat
GH
Whey – set 1
Study case 1Feed contamination
Feed mill contamination
LWPCA
Feed mill contamination
Study case 1Feed contamination
Study case 2Milk contamination
Study case 2Milk contamination
Study case 2Milk contamination
These results show that no clear conclusion can be obtainedwhen looking directly at the spectra.
GH values detect abnormalities at levels higher than 500 ppm.
LWPCA allows detecting contamination at levels up to 100ppm; however at those levels the detection of melamine in milkbecomes unstable, which is an indication that the technique hasprobably reached its limit of detection.
Study case 2Milk contamination
Local moving window PCA method is proposed for thecharacterization of agronomical products and the detection ofpossible contaminants using vibrational spectroscopy.
In the examples presented here, soybean meal and liquid UHTsamples have been contaminated with melamine/whey, makingthem thus semi-targeted studies.
However the method should be used as a method for the untargeteddetection of abnormalities (real contamination or fraud) in the dataand a previous step for further analyses.
Local discrimination modelling
Conclusion
NIR spectroscopy in combination with a chemometricsbased protocol is a perfect tool, at laboratory and atindustry levels, for:
- the characterization of food/feed materials- Detection of targeted and untargeted
adulteration / contamination
Conclusion
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