# A Review of Milk Frauds and Adulterations from a Technological Perspective
## 3 Results and Discussion
### The Most Common Milk Adultrations
#### 3.1.2 Adulterations Involving the Increased Protein Content  
Adulterants rich in nitrogen have become a well-known topic in recent years, mainly because of food safety incidents. This adulteration is common and difficult to detect because the Kjeldahl and Dumas methods that are used to quantify the total protein content of milk cannot distinguish the nature of the non-protein nitrogen. The most commonly used adulterants in this category are whey, melamine, and urea, and this is because of their high nitrogen content and low cost [3; 11; 13]. According to the World Health Organization, melamine is a nitrogen-rich substance that is used to increase the apparent protein content and therefore the economic value of milk. Until melamine contamination was reported in China in 2008, the limit of melamine in EU food legislation was not established. Both the European Commission and the United States Food and Drug Administration imposed the maximum allowable limit, which was later followed by the Codex Alimentarius Commission in a new ruling in 2010. According to Regulation 1881/2006, the maximum level of melamine in food, except infant formula, is 2.5 mg/kg, and in powdered infant formula and follow-on formula, the maximum level allowed is 1 mg/kg. Although harmful and causing kidney and urinary problems, including infant death when it reacts with cyanuric acid, melamine is not a carcinogenic compound and has low oral toxicity. The toxic dose of melamine is on par with tht of common table salt, with an average lethal dose (LD50) greater than 3 g per kilogram of body weight [8; 12; 29]. The following are some of the ways that melamine can get into milk and milk-related products: adulteration of milk by direct addition to increase protein content; the application of the insecticide cyromazine on crops (cyromazine is converted to melamine in the animal's body and may therefore be present as a contaminant in the animal's milk and tissues); utilization of fertilizers with nitrogen when the nitrogen source \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Models**} & **Density** & **Viscosity** & **Freezing** & \multirow{2}{*}{**pH**} & **Fat of Milk** \\  & **[g/cm\({}^{3}\)]** & **[mPas]** & **Point [\({}^{\circ}\)C]** & & **[\%]** \\ \hline Undiluted milk & 1.0571 & 33.83 & \(-0.501\) & 6.70 & 3.20 \\
5\% H\({}_{2}\)O & 1.0531 & 32.83 & \(-0.484\) & 6.72 & 3.00 \\
10\% H\({}_{2}\)O & 1.0517 & 32.63 & \(-0.457\) & 6.73 & 2.90 \\
15\% H\({}_{2}\)O & 1.0505 & 31.63 & \(-0.433\) & 6.75 & 2.80 \\
20\% H\({}_{2}\)O & 1.0478 & 31.33 & \(-0.405\) & 6.76 & 2.55 \\
25\% H\({}_{2}\)O & 1.0469 & 30.90 & \(-0.378\) & 6.77 & 2.45 \\
30\% H\({}_{2}\)O & 1.0447 & 29.27 & \(-0.352\) & 6.78 & 2.25 \\
35\% H\({}_{2}\)O & 1.0436 & 28.90 & \(-0.327\) & 6.78 & 2.00 \\
40\% H\({}_{2}\)O & 1.0430 & 28.73 & \(-0.301\) & 6.80 & 1.80 \\
45\% H\({}_{2}\)O & 1.0412 & 27.90 & \(-0.275\) & 6.80 & 1.73 \\
50\% H\({}_{2}\)O & 1.0397 & 27.13 & \(-0.250\) & 6.81 & 1.48 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Variations of milk quality control parameters according to the degree of dilution with water. is melamine; transfer of melamine from dairy industry plastics and packaging materials; permeation in cows' milk and tissue when animals graze on fertilized pasture (melamine is fast transferred from grass to milk in 8 h, with a 3% efficiency for low concentrations and a 2.1% efficiency for pastures with high melamine concentrations) [29]. Urea is used as an adulterating agent in milk when water is added to it in order to reduce the milk's density and whiteness. Urea acts as a preservative, increases solid-non-fat and non-protein nitrogen, decreases titralable acidity, and suppresses milk fermentation. At the same time, it makes the milk viscous, giving the impression of thicker milk. Urea, being a natural component of milk, accounts for most of the non-protein nitrogen in milk, i.e., 55%.