Condensed milk concentration line

The production of condensed milk with sugar can be carried out in accordance with various technologies and recipes, but most manufacturers recipes are based on GOST standards, which define high production requirements and clearly regulate the processes. Therefore, our company has specially developed a mini production line, which, even with its low productivity, fully reflects the entire GOST technology for the production of sweetened condensed milk from normalized whole milk.

In a milk concentration and condensation line equipped with various options, a wide range of processes can be performed to meet the customers' requirements, including:

Basic equipment required for milk concentration:

The vacuum evaporation unit comprises a 3-layer conical vacuum reactor (with thermal insulation and an external decorative casing made out of polished stainless steel), which is equipped with a forced circulation circuit with a pump for thick and viscous products and a plate heat exchanger. Heating is carried out by an external heat exchanger, where steam is supplied at a pressure of about 3 bar. Hot normalized and pasteurized milk with a temperature of 95-98 degrees is fed into the rarefied environment of the vacuum reactor through a tangential feed, where it spreads in a thin layer along the walls. The water contained in the milk almost immediately begins to evaporate due to the lower boiling point of water under vacuum, secondary steam appears, which is drawn through a trap into the vapor condensation system - the condenser. For the condenser to work properly, you must connect it to a source of ice water. Evaporation occurs at a temperature of about 60 degrees. The evaporation process is carried out cyclically: milk constantly circulates through a heat exchanger and is fed into a vacuum reactor, this process is repeated until the required level of dry matter concentration and mixture density are achieved. During the concentration process, samples can be taken through a special sampling valve. The basic version includes a piping system with shut-off and control valves as well as mechanical valves.

The density of condensed milk is usually 1061-1063 kg/m3.

The installation includes a vacuum generation system, pump-product control and a temperature controller for adjusting the heating temperature.

Additional options:

• Syrup sprayer for better mixing of milk with the finished syrup. It is recommended to serve the syrup at a temperature of about 90-95 degrees, since at lower temperatures there may be problems when mixing the syrup and milk, and at higher temperatures the proteins of the condensed milk may coagulate.
• To determine the content of dry substances, we also offer flow refractometers, which are installed in the piping of the circulation circuit. There is no need to stop the process and open it or take samples mechanically; the data can be monitored directly during the process on the refractometer display.
• Steam generator for supply to the heat exchanger with a pressure of 3 bar.
• Ice water station with a chiller

In production lines for sweetened condensed milk with a capacity of 285 kg/hour, we also offer inclined models of vacuum evaporation units with the possibility of equipping them with jackets and an electrically driven mixing device.

To obtain concentrated milk or cream, just the single installation described above is sufficient, but depending on the desired processes and recipes, additional equipment can be offered as well:

• The syrup cooking station consists of a 60 liter cooking kettle operating on thermal oil inside which the sugar for the production of syrup is dissolved; the temperature in the thermal oil jacket can reach a maximum temperature of 150 degrees. This cooker has a mobile wheel support with locks, insulation of the working vessel and an upper safety spiral above the stirring device. Sugar syrup is prepared by mixing granulated sugar with hot water, the temperature of which is 60-70°C. After boiling the mixture, it must be cooled down to 90-95 degrees. It is recommended to prepare syrup variations with a sugar concentration of 65-70%. The syrup is boiled under atmospheric conditions in parallel with the concentration of the milk, and is added at the end of the milk boiling process to achieve the desired consistency.

In some recipes, sugar is introduced into the vacuum evaporation unit simultaneously with milk. This technology simplifies the production process, thereby reducing the boiling time for milk (while also improving the energy efficiency of the process). The addition of sugar to milk is commonly employed in the production of skim sweetened condensed milk. However, this method may have its drawbacks, depending on the quality of the sugar. When dry sugar is added to pasteurized milk, various microorganisms can contaminate the mixture. Therefore, in the production of condensed canned food, pre-prepared sugar syrup is typically used. It is also advisable not to store the prepared sugar syrup for longer than 20 minutes after boiling, until it is mixed with condensed milk in the vacuum evaporation unit. Upon cooling, the syrup may undergo structural changes, thickening or becoming sugary, while chemical changes in its composition may occur due to sucrose hydrolysis, leading to the breakdown of sucrose into glucose and fructose. The station may feature an independent control panel, or, depending on the model, temperature and rotation speed control for the mixing device may be integrated into the vacuum evaporation unit's control panel.

• • As an option, we additionally offer a flow-through stainless steel filter for the syrup brewing station.
  • We also provide a product pump for syrup, which assists in pushing the product through the filter during loading.

• The milk pasteurizer comprises a batch pasteurizer equipped with a jacket for the coolant, allowing for the introduction of steam or hot water from an external supply source. This capacitive pasteurizer serves as an optional addition, chosen by customers who do not have a pasteurization unit in their production line. Prior to loading into the working container of the evaporation unit, milk must be supplied at a minimum temperature of 95 degrees Celsius. Additionally, the heating circuit of the vacuum evaporation unit can be utilized for heating milk, depending on the specific modification.

• The vacuum crystallizer is designed for the controlled crystallization of the finished mixture of condensed milk with sugar. It is equipped with an external circulation loop directed through a heat exchanger for effective cooling of the product. This process is one of the most important in the production of condensed canned food, as it has the greatest impact on the quality of the final product. To achieve the desired crystallization structure, a seed is added (in the form of dry crushed lactose, at least 0.2% of the product's mass with crystal sizes of 2-3 microns). Condensed milk from previous brews can also be used as a seed, in an amount of at least 10%. In uncooled condensed milk with sugar, lactose exists in the form of a saturated solution; upon cooling, the solution becomes supersaturated, initiating crystallization. The product is also briefly boiled in the crystallizer. A special screw pump for thick and viscous products and a heat exchanger are installed in the circulation circuit of the crystallizer to increase the cooling intensity. It is necessary to ensure rapid cooling of the mixture, preferably without air exposure. Condensed milk is typically quickly cooled to a temperature of 30-35 degrees Celsius, at which point lactose is added, and then the mixture is cooled to the crystallization temperature (around 20 degrees Celsius). After crystallization is complete, the product acquires a thicker and denser, homogeneous, and delicate structure.

For cooling, it is necessary to supply a source of ice water, both to the crystallizer jacket and to the remote heat exchanger. The basic version of the vacuum crystallizer-cooler includes a vacuum reactor with a coolant jacket, a vacuum generation system and an adjustable mixing speed for a stirrer with fluoroplastic scrapers.

The cooled condensed milk is then unloaded into a storage tank, where it is stored for some more time to consolidate the results of crystallization.

• Simmer-crystallizer for boiling condensed milk. The milk simmering process is carried out in a universal cooking container both under vacuum and under pressure up to 0.5 Bar, where the product is slowly simmered. Heating is carried out through the installations jacket, where steam or hot water is supplied from an external source.