*2.3. Commercial Milk Analyzers*

Dairy farming and working conditions are changing at a fast pace. Dairy farms today use modern automation tools, embrace digital technologies, and implement intelligent solutions for profitable and efficient milk production. The market for equipment for the analysis of milk and dairy products is very diverse and is constantly being replenished with various new models, both from manufacturers that have been working in this field for a long time, and from manufacturers previously not present on the market. All equipment can be conditionally divided into two groups: which operates on the basis of direct methods of analysis (extraction, weighing, etc.) and equipment that uses indirect methods of obtaining data on the composition of the sample.

The first group includes any devices that determine the mass, temperature, and equipment designed to conduct the actual chemical analysis with varying degrees of automation. For example, "Kjeldahl devices", which are represented by a wide variety of models in a wide price range, but, accordingly, with the same wide range of capabilities.

The second group includes instruments using instrumental analysis methods. This is a large number of various devices using spectroscopy in different ranges [34–36], devices using ultrasonic vibrations [37,38], measuring the optical activity of the sample, as well as "combined devices", in which two methods can be applied at once, or preliminary sample preparation (for example, precipitation or "binding" of any component of the sample), followed by analysis of the sample thus obtained by a standard method (for example, optical spectroscopy).

About 10 years ago, the study of milk and dairy products was only possible under laboratory conditions, and was based on chemical or physicochemical methods. Since these are direct methods, they are considered the most reliable, but such an analysis is a laborious, long-term (analysis could take up to 15 h) process that requires experience and specialized knowledge from personnel, high-purity chemicals. This leads to an increase in the cost of the examination of raw materials, in addition, the accuracy of the results may decrease because of imperfect reagents, the human factor—laboratory assistant errors and subjective assessment of the results. Often a situation arises when the indicators of the device used, calibrated according to the manufacturer's data, differ from the indicators obtained by reference methods, for example, the Gerber method for determining fat. The difference can be significant, say 0.3% fat. With the apparent simplicity of the method, forgetting about its intricacies can lead to systematic errors in the analysis. For example, the temperature regime is not maintained, the isomeric composition of the isoamyl alcohol used is not monitored. This leads to discrepancies between the readings of the milk analyzer and the results obtained from the chemical analysis data precisely because the control analysis method (Gerber's method) was performed incorrectly.

In addition, the modern pace of life and production constantly requires an increase in the speed of all stages of production. Owing to new technologies, quality analysis is carried out much faster and does not depend so much on the qualifications of employees. Therefore, now more and more often give preference to analyzers that use indirect methods of data collection.

Despite all the advantages of modern analyzers, there are areas that still need to be refined. Equipment for agricultural producers must meet a number of requirements. First, it should be inexpensive and competitive. So the average cost for present analyzers ranges from 340 € to 22,660 € and more, depending on the modernization (Table 3). Second, it should be easy to use. If we talk about the analysis of milk quality directly on farms, then the best option is the ability to adapt to any milk pipeline, without making significant changes to the structure of the milk pipeline and without breaking the vacuum regime. Third, the analyzer must take into account the heterogeneity of the milk flow in the milk pipe. Milk is a complex polydisperse system. Milk sugar (lactose) is dissolved in a dispersed medium (water: 85–89%) of milk, the size of its molecules is 1–1.5 nm. Milk salts are in the form of colloidal particles, protein substances form colloidal solutions. Milk fat is in a warm state in the form of an emulsion, in a cold state—in the form of a suspension. The process of milk movement through the pipeline of the milking installation is unsteady, from laminar to turbulent modes. It is also necessary to take into account the heterogeneity of the milk-air flows because of the mechanical effect on the milk, leading to foaming. This complicates the determination of milk quality parameters. Fourth, the analyzer must carry out tests as quickly as possible. The best option is to work in real time, directly in the stream. There is currently no automatic counter-sensor for linear installations. Non-independent manufacturers (De Laval, GEA PHARM Technologies, etc.) offer mobile milking machines for use. They have small dimensions and do not interfere with the measured flow. However, they have a significant cost and high error (up to 10–12%, with the maximum allowable rate not exceeding 5%). Thus, at the moment there are no analyzers that could meet all modern requirements.


