Ministero delle Politiche Agricole Alimentari e Forestali, Dipartimento dell'Ispettorato Centrale della Tutela della Qualità e della Repressione Frodi dei Prodotti Agroalimentari, Laboratorio centrale di Roma, Via del Fornetto 85, 00149 Rome, Italy.
Rapid Commun Mass Spectrom. 2010 Mar;24(6):705-13. doi: 10.1002/rcm.4426.
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.
乳制品领域常见的欺诈行为是在山羊奶酪中添加绵羊奶，因为它的味道与羊奶非常相似，但更容易获得，并且通常被认为具有更好的凝乳能力。出于类似的原因，并且由于经济上的便利，绵羊奶酪也可能含有欺诈性的牛奶。为了检测这种欺诈行为，可以使用欧盟的官方方法，但它只是一种定性方法（存在/不存在牛奶）。开发了一种能够在山羊奶酪和牛奶奶酪的奶酪生产过程中定量检测绵羊奶存在的方法。该方法基于奶酪中酪蛋白提取物的液相色谱/电喷雾电离串联质谱（LC/ESI-MS/MS）分析。通过简单的程序，从奶酪中提取、溶解酪蛋白，用纤溶酶消化，然后用 LC/ESI-MS/MS 分析。准确选择并分析由纤溶酶水解产生的典型绵羊肽（m/z = 860），以了解宣称的纯山羊奶酪中是否含有绵羊奶，以及含量是多少。通过分析相同的肽，还可以检测宣称的纯绵羊奶中是否含有牛奶，以及含量是多少。该方法应用于几种山羊奶酪和牛奶奶酪样品。通过分析含有不同比例绵羊奶的凝乳奶酪获得校准曲线进行定量。评估了方法检测限和方法定量限。该方法似乎准确且适用于检测奶酪中高达 2%的绵羊奶。
