Peptidomic approach, based on liquid chromatography/electrospray ionization tandem mass spectrometry, for detecting sheep's milk in goat's and cow's cheeses.
A common fraud in the dairy field is the addition of sheep's milk to goat's cheeses, because it has a very similar taste to goat's milk, but is more available, and is commonly considered to have a better capacity to curdle. For similar reasons, and due to economic convenience, sheep's cheeses may also contain fraudulent cow's milk. In order to detect this fraud, an EU official method may be used, but it is only a qualitative method (presence/absence of cow's milk). A method able to quantify the presence of sheep's milk during cheese production in goat's and cow's cheeses was developed. The method is based on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) analysis of peptides of a casein extract from the cheese. By a simple procedure, caseins are extracted from cheeses, solubilized, digested with plasmin, and subsequently analyzed by LC/ESI-MS/MS. A typical sheep's peptide produced by plasmin hydrolysis (m/z = 860) was accurately selected and analyzed to understand if, and by how much, a declared pure goat's cheese contains sheep's milk. By analyzing the same peptide it is also possible to detect if, and by how much, a declared pure sheep's milk contains, or not, cow's milk. The method was applied to several goat's and cow's cheese samples. Quantitation was performed with a calibration curve obtained by analyzing curd cheeses containing different percentages of sheep's milk. The method detection limit and method quantitation limit were evaluated. This method appears accurate and suitable for detecting up to 2% of sheep's milk in cheeses.
Guarino C
，Fuselli F
，La Mantia A
，Longo L
，Faberi A
，Marianella RM
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Effects of Cow's Milk Components, Goat's Milk and Sheep's Milk Sensitivities on Clinical Findings, and Tolerance Development in Cow's Milk Allergy.
Cow's milk (CM) contains some proteins capable of causing an allergic reaction in a sensitized individual and one of the most common causes of food allergy in childhood. Most of the patients will develop tolerance by the age of 3. In this study, we aimed to evaluate sensitivity to CM allergen components as well as goat's milk (GM) and sheep's milk cross reactions in cow's milk allergic (CMA) patients and to figure out the risk factors for tolerance non-development.
This is a retrospective cross-sectional study including 66 patients for IgE-mediated CMA with mean age of 38 months. We evaluated the patients in two groups: Group 1 (n=50): Patients who have no tolerance in oral food challenge test; Group 2 (n= 16): Patients who were found tolerant to CM after elimination diet. Cow's milk-spesific IgE(sIgE), α-lactalbumin(ALA)-sIgE, β-Lactoglobulin(BLG)-sIgE, casein-sIgE, goat's milk-sIgE, sheep's milk-sIgE, skin prick tests(SPTs) with CM and GM, eosinophils in peripheral blood were all compared between two groups.
In the whole group, goat's milk-sIgE and sheep's milk-sIgE were positive in 84.8% and ALA-sIgE, BLG-sIgE, casein-sIgE were positive in 69.7%, 62.7%, 77.3% of the patients, respectively. Two groups were similar in terms of age at onset and diagnosis, gender, median elimination period, total IgE levels, cow's milk-sIgE and eosinophilia (p>0.05). Mean wheal diameters of CM and GM in SPT (p<0.001), goat's milk-sIgE (p=0.03), sheep's milk-sIgE (p=0.01) were significantly higher in Group 1. Cow's milk-sIgE showed a positive correlation with total IgE (p=0.001), eosinophilia percentage (p=0.04), CM wheal diameter in SPT (p=0.001), casein-sIgE (p<0.001), goat's milk-sIgE (p<0.001), sheep's milk-sIgE (p<0.001) in Group 1. Patients with respiratory symptoms and history of anaphylaxis had higher cow's milk-SPT, cow's milk-sIgE, casein-sIgE, goat's milk-sIgE, sheep's milk-sIgE levels(p<0.05). Gastrointestinal and skin symptoms showed no relation with laboratory findings. Any patient with a history of anaphylaxis did not develop tolerance.
As with cow's milk-sIgE levels and high induration diameters in SPT; high casein-sIgE, sheep's milk-sIgE and goat's milk-sIgE levels are also risk factors for persistence of CMA. Anaphylaxis, as a first reaction, may also be a risk factor. High cow's milk-sIgE, casein-sIgE, sheep's milk-sIgE, goat's milk-sIgE levels are associated with respiratory symptoms.
Gunaydin NC
，Severcan EU
，Akarcan SE
，Bal CM
，Gulen F
，Tanac R
，Demir E
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Detection of sheep and goat milk adulterations by direct MALDI-TOF MS analysis of milk tryptic digests.
In dairy field, one of the most common frauds is the adulteration of higher value types of milk (sheep's and goat's) with milk of lower value (cow's milk). This illegal practice has an economic advantage for milk producers and poses a threat for consumers' health because of the presence of hidden allergens as, for example, cow milk proteins, in particular, α(s1)-casein and β-lactoglobulin. The urgent need of sensitive techniques to detect this kind of fraud brought to the development of chromatographic, immunoenzymatic, electrophoretic and mass spectrometric assays. In the current work, we present a fast, reproducible and sensitive method based on the direct matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) MS analysis of milk tryptic digests for the detection of milk adulteration by evaluating specie-specific markers in the peptide profiles. Several pure raw and commercial milk samples and binary mixtures containing cows' and goats', cows' and sheep's and goats' and sheep's milk (concentrations of each milk varied from 0% to 100%) were prepared, and tryptic digests were analyzed by MALDI-TOF MS. The use of the new MALDI matrix α-cyano-4-chlorocinnamic acid allowed to detect cow and goat milk peptide markers up to 5% level of adulteration. Finally, from preliminary data, it seems that the strategy could be successfully applied also to detect similar adulterations in cheese samples.
Calvano CD
，De Ceglie C
，Monopoli A
，Zambonin CG
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