The processes of cleaning and filtering milk are designed to eliminate contaminants and natural unwanted impurities from its composition. There are different ways to solve such problems, which differ in technological organization, efficiency, productivity and performance. The equipment for milk purification, which is equipped with production lines, also varies.
General cleaning technology
All processing operations are carried out in special conditions that meet technical and sanitary requirements. The standards applied to the organization of work of food enterprises are taken as a basis. On dairy farms, both individual technological processes for processing raw materials and complex product preparation can be carried out.
The main cleaning methods are implemented today on milk separators and centrifuges with pasteurizers. At a minimum, this equipment allows you to remove mucus from milk plasma, solids, and dirt particles. Finer filtering also gives a disinfection effect with the destruction of harmful bacteria. Methods for the purification of milk through thermal and biological effects are also developing. In such treatment systems, the physicochemical properties of milk are modified, the content of surfactants (proteins, phospholipids, fat globules and acids) is optimized and surface tension is reduced.
Delivery of raw milk to production
The transfer of milk between departments on the farm or its delivery by transport to the processing plant is carried out in special containers or tanks with refrigerators. According to the requirements, the inner surfaces of tanks and reservoirs must be made of stainless steel or aluminum. External surfaces are finished with heat-insulating material. In the process of moving, it is important to maintain the optimum temperature regime of raw milk. So, the average temperature is 4-6 ° C. In this state, the raw material can be contained no more than 10 hours. If a longer transportation is planned, then a special milk cooler is initially involved - equipment in the form of a tank, which immediately after milking lowers the temperature of the liquid product from 35 to 4 ° C. At the same time, pathogenic elements of the composition are removed and useful qualities are preserved.
Cooling modes
The properties of milk, and in particular its bacteriological characteristics, will to a large extent depend on the temperature of its further storage. If you leave the product uncooled, then after 10 hours its content, its acidity will increase by almost 3 times, and with it the number of unwanted bacteria will increase sharply. For optimal storage from the point of view of favorable microflora, long-term maintenance at the plants requires maintaining a regime of 12 ° C. Strong cooling is also not recommended, since it is detrimental to beneficial microorganisms. Again, a milk cooler comes with the aid of control sensors and an automatic temperature control system, which takes into account several physical and chemical properties of milk. Such equipment may contain from 100 to 1000 liters at the same time, depending on the model and production needs. The choice of specific cooling tactics will depend on the time of keeping, but short periods at different stages of milk cleaning and processing usually require maintaining 4-6 º.
Basic machining
Also, this process can be called centrifugal separation - this is one of the basic cleaning procedures, involving the separation of milk into fractions of different densities. For example, skim and high fat milk (cream) may be separated. Technically, the process is organized at the facilities of a separator with a rotating drum. The installation operator monitors the following parameters of the mechanical purification of milk during its operation:
- Drum rotation speed.
- The rate of release of globules of fat.
- Density of fat and plasma.
- Viscosity.
As the size of the density of milk plasma and fat globules increases, the rate of separation and release of creamy mass accelerates. In turn, an increase in viscosity helps to reduce the rate of separation of fat fractions. The temperature and acidity of milk have an indirect effect on the centrifugal treatment of milk. Acidity can change the protein mass of milk by increasing its colloidal state. As a result, the process of precipitation of flakes will begin against the background of an increase in viscosity and difficulty in separation. As for the temperature effect, its increase reduces the level of viscosity and slows down the transition of the fatty fat mass to a liquid state. Therefore, before separation, it is recommended to heat milk to 35–45 ° . An increase in temperature will provide a more efficient degreasing process.
Separators for milk purification
The above operations of separation of milk fractions and purification are performed on special separators. As a rule, these are electric machines with a built-in motor, a collector, a bowl for loading milk and a centrifuge. On medium-sized farms, devices with a capacity of up to 50-70 l / h are widely used. In this case, the rotational speed of the drum can reach 12,000 rpm. Modern equipment for dairy production has the means of automated control and protection. Monitoring and control is implemented through a combination of sensors and a controller with an operator panel. Having set the desired program, the user starts the separation process with robotic control in accordance with the established milk processing algorithms. Protective systems are mainly represented by devices that prevent electrical and thermal overloads.
Milk filtration
Also one of the initial processes for preparing dairy raw materials for biological and chemical treatment. The main task at this stage is to remove contaminants that have gotten during milking or storage by filtration. Filters themselves can have a different device. So, closed-type membranes rid the liquid of large mechanical impurities. Typically, these filters are installed on the lines of a production milk line and milking systems. The quality and degree of cleaning depth will depend on the characteristics of the material used. The most effective fine filter for milk made from non-woven fabric. Sometimes in one circulating circuit or in a milking unit , several filtering devices are used to delay particles of different fractions.
Bactericidal cleaning phase
This is a time period during which microorganisms that get into milk do not multiply, but die. In this phase, the crude product is characterized by the presence of natural bactericidal properties provided by antibacterial substances. These include leukocytes, normal antibodies, lysozymes, etc. This ability of milk will depend on the physiological condition of the livestock from which it was obtained. The duration of bactericidal purification of milk is determined by the external microflora and storage temperature, but usually does not exceed 2-3 hours. In the future, it will be important not so much cleaning as such, as the technological processes of maintaining the life of antibacterial substances. The main measures of this kind include primary cooling, and filtration, as well as the introduction of enzymes that fight toxins that cause milk defects.
Thermal milk treatment technology
Heat treatment is used to disinfect dairy raw materials. In the process of its implementation, not only the destruction of microorganisms with products of their vital activity occurs, but also favorable conditions are created for maintaining and maintaining the beneficial properties of milk. It should be noted that, in itself, the temperature effect in any form destroys the primary physicochemical structure of the raw material. The degree of change will depend on the duration and temperature of the treatment. On dairy farms, this operation is performed by special tubular, capacitive and plate heaters. Multifunctional heat treatment equipment also includes a pasteurization bathtub.
Conclusion
The effectiveness of preparing dairy raw materials for further processing is largely determined by its initial state. Not every raw material is, in principle, suitable for use in the food industry. There are special standards and requirements that determine the suitability of the product for procurement. After a check of physico-chemical and biological indicators, milk purification begins according to the previously designated scheme. This can be separate chemical processing operations with filtration, and deep comprehensive separation with improved bacterial microflora of the product. The specific set of technological operations of cleaning will depend on the tasks of procuring a dairy product at the farm or production line.