Wiltsche Helmar 1 Determination of calcium by EDX a fast method for the determination of mechanically recovered meat (MRM)
Professor Horst Cerjak, 19.12.2005Wiltsche Helmar 1
Determination of calcium by EDX
a fast method for the determination of mechanically recovered meat (MRM)
Professor Horst Cerjak, 19.12.2005Wiltsche Helmar 2
What is mechanically recovered meat?
EC Regulation No 853/2004 (Annex I): “…the product obtained by removing meat from flesh-bearing bones after boning or from poultry carcasses, using mechanical means resulting in the loss or modification of the muscle fiber structure”
Professor Horst Cerjak, 19.12.2005Wiltsche Helmar 3
Production of mechanically recovered meat
Various methods for separating bones from MRM
Drum-belt separator Endless screw separator
Images from EFSA Journal, 2013, 11.
Professor Horst Cerjak, 19.12.2005Wiltsche Helmar 4
Bone fragments
• Mechanically recovered meat contains small bone fragments
Image from P. Komrska et al. , Acta univ. agric. et silvic. Mendel. Brun., 2010, 59, 145-152
MRM stained with Alizarin Red and Trichrome Green
Professor Horst Cerjak, 19.12.2005Wiltsche Helmar 5
Analytical implications
• Calcium can be used as marker element for MRM:
• Ca content of bone ash is constant (36.3 – 36.9 % Ca)[1]
• Low Ca concentration in meat
• Samples will be heterogeneous
• Homogenization of a larger sample mass prior subsampling
[1] C. Blincoe, A. L. Lesperance and V. R. Bohman, Journal of Animal Science, 1973, 36, 971-975
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Regulatory requirements
• EC Regulation No 2047/2005
• Ca in MRM “shall not exceed 0,1 % of fresh product”
• Austrian food codex, Chapter B14
• MRM mustn’t be used for the production of sausages
• Ca content < 200 mg/kg if bone particles are present
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“Traditional” way of analyzing Ca
Sample
homogenization
Digestion in
acid (HNO3)
Ca quantification
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Alternative approach: EDX
Sample
homogenizationCa quantification
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Determination of Ca
• Samples
• 3 different types of sausages
• Liver meat paste
• Dog food
• Homogenization
• Büchi Mixer (500 g batches)
• Retsch Cryo Mill for homogeneity studies
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EDX: Ca determination
• Gravimetrically prepared standards in the range of 400 – 1600 mg kg-1
• Standard conditions for Ca in the Shimadzu EDX 8000
• Collimator: 10 mm
• Integration time: 100 s
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EDX: Ca calibration
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EDX: Ca determination
• EDX limit of quantification (LOQ): 170 mg kg-1
• Reference digestions and Ca-quantification of several samples (sausages and pet food) by ICP-OES
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Comparison EDX / classical approach
Sample Reference value (ICP-OES) EDX
Sausage (Krakauer) 42 ± 1 mg/kg < LOQ (160 mg/kg)
Sausage (Huber) 52 ± 2 mg/kg < LOQ (160 mg/kg)
Sausage (Tann) 48 ± 1 mg/kg < LOQ (160 mg/kg)
Liver meat paste (Inzersdorfer) 83 ± 2 mg/kg < LOQ (160 mg/kg)
Dog food (Pedigree) 2610 ± 80 mg/kg 2690 ± 70 mg/kg
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Spike concentration: 1000 mg kg-1 Ca
EDX: Spike recovery
0
20
40
60
80
100
120
140
160
Sausage(Krakauer)
Sausage(Huber)
Sausage(Tann)
Liver meatpaste
(Inzersdorfer)
Dog food(Pedigree)
Spik
e re
cove
ry, %
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Conclusion: Spike recovery
• Spike recoveries in general acceptable – potential problems with the homogenization of the Ca-standard into the sample
• relatively high RSD’s for EDX
• some samples were particularly rich in fat
• Sample heterogeneity was troublesome in ICP-OES
• although some sausages “look” homogeneous, they aren’t!
• Production of the sausages can have an effect on the distribution of the raw materials
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Time required for an analysis
“Traditional” approach:
Acid digestion and ICP-OES
• digestion of 16 samples 60 min
• ICP-OES: 60 min (including calibration)
about 7-8 min per sample
EDX
less than 2 min per sample
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Conclusion
• EDX provides a fast and reliable method for screening meat products
• LOQ sufficient for Austrian food codex (and similar regulations throughout the EU) identification of products potentially containing MSM
• Requirements of EC Regulation No 2047/2005 are easily fulfilled in terms of LOQ
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Acknowledgements
• Shimadzu
• Florian Zand and Herbert Motter
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Thank you for your attention!