Vacuum evaporator: what it is for and how to choose one

In brief. A vacuum evaporator (VVU) heats the product under vacuum and evaporates water from it at a reduced temperature. The product does not burn and keeps its flavour and colour — which is why good condensed milk is cooked in a VVU rather than in an ordinary cooking kettle. Milberg units are most often used to cook condensed milk and dulce de leche (boiled condensed milk), jams, fruit butter, preserves and sauces; the most popular volume is 500 L. The key selection criteria are vacuum depth and the vacuum pump: this is where cheap units cut corners. Milberg VVU prices start from €8,900.

What a vacuum evaporator is for

The job of a VVU is to concentrate the product — that is, remove part of its water — without overheating it. A vacuum is created in the vessel, and at reduced pressure the product boils at a temperature well below 100 °C. The water evaporates, while the product does not burn, darken or pick up a caramelized taste.

What is most often cooked in Milberg VVUs:

• sweetened condensed milk and dulce de leche (boiled condensed milk);
• jams, fruit butter and preserves;
• sauces and pastes.

The same units are used in cosmetics, pharmaceutical and chemical production — wherever water needs to be removed from a product without overheating it.

Why condensed milk cannot be cooked in an ordinary kettle

"You will never cook good condensed milk in an ordinary cooking kettle: it cooks at a high temperature, and that affects the taste. You need a vacuum and low-temperature cooking under that vacuum." — Alexey Troshin, Director of the Milberg plant

A cooking kettle is good for its own tasks — general-purpose cooking of dairy and food products, including home-style condensed milk. But industrial-quality condensed milk requires a vacuum: either a vacuum version of the kettle or a vacuum evaporator.

Condensed milk made to GOST (the Russian standard) is produced by evaporating water — which is exactly what a VVU is for. In recipes made to TU (manufacturer's specifications), the evaporation stage is eliminated altogether. If you produce condensed milk, dulce de leche and heat-stable fillings in volume, take a look at the condensed milk production line — we build it to GOST or TU, for whole milk or milk powder.

How to choose a vacuum evaporator

1. Vacuum depth — where corners get cut

The deeper the vacuum, the lower the boiling point and the better the taste and colour of the finished product. The most common buyer mistake is to underestimate vacuum depth and opt for a cheaper unit. Cheap units have thinner metal and a weaker vacuum, which means cooking at a higher temperature.

2. Vacuum pump

Cheap units are fitted with an ordinary air compressor. It is not suitable for a deep vacuum and wears out very quickly. Milberg fits liquid-ring vacuum pumps: they are designed for deep vacuum and last much longer.

3. Volume

The volume is chosen to match the batch size and production plan. Our customers most often choose a 500 L VVU. We also make smaller units — for example, 60 and 150 L — and larger ones to suit the task.

4. Design for the product

A standard Milberg VVU includes:

• a full-volume heating jacket with electric heating elements, with water or propylene glycol as the heat-transfer medium;
• a strip cooling jacket on the shell;
• a frame agitator with scrapers on a geared motor with a frequency converter;
• 50 mm PU foam insulation, a conical bottom and a DN 300 manway;
• a DN 100 sight glass and a vacuum gauge;
• a cleaning head and a 10 L loading funnel with a butterfly valve.

Steel grades: AISI 304, 316 or 321. The agitator, steel and vacuum pump are selected according to the type and properties of the product.

5. Control

The basic version is a control panel with a temperature controller using two sensors (jacket and product) and agitator control. For serial production — full automation that runs the cooking according to recipes.

How Milberg VVUs are delivered

Every VVU is manufactured at our factory, tested before shipment and handed over to the customer with documentation for installation and start-up. The unit can be used to produce sweetened condensed milk and concentrated milk and to concentrate whey — a product that many plants simply dispose of. Our completed deliveries are in the Projects section.

How much a vacuum evaporator costs

A Milberg VVU costs from €8,900. The final price depends on volume, steel, pump and level of automation. A complete condensed milk production line starts from €11,200.

Tell us what you cook and what batch size you need — we will select a unit and send a quotation within one business day. All equipment in this area is in the "Vacuum evaporators" section.