2.2.5. Falsification

On the list of the most counterfeited foods in the world, milk follows immediately after olive oil; over the past 30 years, milk has featured in 24% of all incidents [27]. Since the composition and properties of milk fluctuate (Table 1) under the influence of various factors, this in practice makes it possible to falsify milk in different ways.

The methods of falsification have practically not changed in recent years. At the moment, two large groups of counterfeit can be distinguished—the falsification of the composition (mainly raw materials) and the falsification of quality. The most common counterfeit is dilution with water [28], milk whey (Table 2), the addition of nitrogen-containing substances, milk substitutes, preservatives [18,22,29].


**Table 1.** Average chemical composition of cow's milk and range of fluctuations in the norm.



The most important components of milk, fats and proteins are objects of falsification. The mass fraction of protein is determined by the official standard methods of Kjeldahl and Lowry [30,31]. For example, the Kjeldahl method calculates the mass fraction of all nitrogenous compounds, then multiplying by a factor of 6.38 to find the mass fraction of total protein in milk. Some of these compounds are normal products of the animal's body and are present in milk normally. But other nitrogen may also be present in the milk—for example, mineral nitrogen compounds that get into the milk with feed, the content of which sometimes exceeds in the feed, or intentionally introduces nitrogen-containing substances to increase the protein content in the milk. According to the Kjeldahl method, the content of any nitrogen will be calculated as milk protein.

When milk fat is falsified, it is replaced with cheaper plant analogues. Such substitutes can be of high quality, characterized by the presence of both hydrogenated and non-hydrogenated fats, and a low level of trans isomers. The most common chemical methods for measuring fat content are the Gerber method [32] and the Rose-Gottlieb method [33]. At the same time, the analyzes last 1.5–2 h, they are sensitive to foreign impurities used in the preparation of samples, chemical reagents are required, which in many cases are harmful to laboratory workers. Receiving milk requires simple, safe, and quick methods.
