Journal of Agricultural and Food Chemistry
Article
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It should be said that the official method used to assess adul-
terations in pasteurized milk14 consists of the HPLC deter-
mination of furosine (few milligrams of furosine per 100 g of
total protein, 8 mg/100 g being the legal limit) that, however, is
naturally present in milk at a concentration of 3−5 mg. The
method here proposed provides an alternative way of looking at
the lactosylation level, overcoming some limitations of the
official method such as the difficulty in detecting the fraud with
powder derivatives from free lactose milk. The detection of lactose
adducts to a 1% level of adulteration correlates with the furosine
measurements in terms of sensitivity.
Conclusions. A simple and sensitive procedure for the
detection of the very challenging adulteration of powdered milk
in liquid (raw and commercial) milk samples has been devel-
oped, based on in-solution digestion of whey and casein frac-
tions followed by MALDI-TOF MS analysis using the new
matrix CClCA. Several modified peptides specific for powdered
milk were detected and identified, and six of them were still
detectable to an adulteration level of 1%. The results obtained
with the in-solution digestion were also in good agreement with
those obtained with the reliable but time-consuming 2D gel
followed by in-gel digestion approach. Future work should address
increasing the number of marker peptides by performing analyses
in negative ion mode using new alternative matrices.43−45
Moreover, the developed approach will also be applied on
control cheese samples such as mozzarella46 made with raw
fresh or adulterated milk.
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́
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discriminating milk heat treatment. Int. Dairy J. 2002, 12, 59−67.
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Measurements of δD and δ18O stable isotope ratios in milk. J. Food Sci.
2003, 68 (7), 2192−2195.
(21) French, S. J.; Harper, W. J.; Kleinholz, N. M.; Jones, R. B.;
Green-Church, K. B. Maillard reaction induced lactose attachment to
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of the lactosylation of whey proteins by liquid chromatography-mass
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(23) Leonil, J.; Molle, D.; Fauquant, J.; Maubois, J. L.; Pearce, R. J.;
Bouhallab, S. Characterization by ionization mass spectrometry of
lactosyl β-lactoglobulin conjugates formed during heat treatment of
milk and whey and identification of one lactose-binding site. J. Dairy
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AUTHOR INFORMATION
Corresponding Author
*Fax: +39-080-5442026. Phone: +39-080-5443589. E-mail:
Funding
Partial funding from Universita’ degli Studi di Bari “Aldo Moro”
is acknowledged.
Notes
■
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We gratefully acknowledge Antonio Trani for his technical
support in carrying out HPLC analyses for furosine
determination. We also acknowledge Dr. Giovanni Ruppi for
helpful discussion.
(24) Morgan, F.; Molle, D.; Henry, G.; Venien, A.; Leonil, J.; Peltre,
G.; Levieux, D.; Maubois, J. L.; Bouhallab, S. Nonenzymatic
lactosylation of bovine β-lactoglobulin under mild heat treatment
leads to structural heterogeneity of the glycoforms. Biochem. Biophys.
Res. Commun. 1997, 236, 413−417.
(25) Carulli, S.; Calvano, C. D.; Palmisano, F.; Pischetsrieder, M.
MALDI-TOF MS characterization of glycation products of whey
proteins in a glucose/galactose model system and lactose-free milk. J.
Agric. Food Chem. 2011, 59, 1793−1803.
(26) Meltretter, J.; Seeber, S.; Humeny, A.; Becker, C.;
Pischetsrieder, M. Site specific formation of Maillard, oxidation, and
condensation products from whey proteins during reaction with
lactose. J. Agric. Food Chem. 2007, 55, 6096−6103.
(27) Fenaille, F.; Parisod, V.; Visani, P.; Populaire, S.; Tabet, J.; Guy,
P. Modifications of milk constituents during processing: a preliminary
benchmarking study. Int. Dairy J. 2006, 16, 728−739.
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