Packaging Methods for Condensed and Evaporated Milk

When condensed or evaporated milk leaves the processing line, it enters one of the most critical stages of its journey – packaging. This step determines how long the product stays fresh, whether it arrives safely to the end user, and if its flavour and texture remain intact over weeks or even months of storage. Unlike regular fluid milk, these concentrated dairy products demand specialised packaging approaches because of their unique composition. Let’s break down the different packaging methods used for condensed milk and evaporated milk, the materials involved, and why sanitary practices during this stage are non-negotiable.

Why packaging matters for concentrated milk products 🔗

Condensed and evaporated milk have had a significant portion of their water removed during manufacturing. This concentration process creates a thicker, richer product – but it also makes the milk more vulnerable to spoilage if exposed to air, light, or microbial contaminants. Packaging serves as the final line of defence. It blocks oxygen that could cause oxidation and off-flavours, prevents light from degrading vitamins, and creates a sealed barrier against bacteria and other microorganisms. According to ScienceDirect, metal cans remain the traditional and widely used containers for evaporated milk because they provide a truly hermetic seal along with excellent protection from gases, light, moisture, and microorganisms.

The two products – sweetened condensed milk and evaporated milk – also follow different packaging workflows. Sweetened condensed milk relies on its high sugar content (typically 62.5-64.5% sugar in the water phase) as a preservative, so it does not need to be sterilised after canning. Evaporated milk, on the other hand, contains no added sugar and must undergo in-container sterilisation after being sealed. This fundamental difference shapes everything from the choice of containers to the sanitary protocols observed during filling.

Packaging of condensed milk 🔗

Condensed milk is packed using two primary formats depending on the end use: barrels for bulk or commercial transport, and cans for retail sale. Each method has specific requirements for materials, temperature control, and hygiene.

Bulk packaging in barrels 🔗

For large-scale commercial use – think bakeries, confectioneries, and ice cream manufacturers – condensed milk is filled into barrels of various sizes, typically ranging from 50 kg to 300 kg. These barrels are constructed from either wood or metal. To prevent the milk from reacting with or absorbing flavours from the barrel material, the interiors are coated with wax or fitted with polyethylene liners.

Before any milk is poured in, each barrel must be sterilised using steam. Once the steam condensate has been allowed to drain, the condensed milk is run into the barrel through the bunghole using a funnel. The ideal filling temperature is around 15.5°C (60°F), which helps maintain the product’s consistency without causing undesirable changes in texture. Once the barrel is full, the bung is driven in firmly to create an effective seal.

The room where barrel filling takes place must meet strict sanitary standards. The atmosphere should consist of filtered air to prevent airborne contaminants from reaching the product. Barrel packaging is cost-effective per unit, reduces packaging waste, and allows efficient transport. However, once opened, the contents need to be used relatively quickly, making this format impractical for household consumers.

Retail packaging in cans 🔗

For consumer markets, condensed milk is packed in cans of various sizes, from as small as 200 grams to 5 kg or more. The can-filling process varies widely depending on the scale of the operation – from hand filling in small dairies to continuous automated filling in large factories.

In large-scale operations, tin sheets are shaped into cans by machines, then immediately filled and sealed. Smaller facilities may purchase pre-made cans and fill them either manually or semi-mechanically. The filling machines typically use either volumetric or gravimetric methods to measure the product into each can, with gravimetric filling being more accurate for consistent product weights.

After filling, the cans are sealed right away to prevent exposure to the atmosphere. Sealing is done either by soldering or by crimping (also called double seaming), which interlocks layers of the can body and lid to form an airtight closure without solder. According to BW Packaging, in double seaming, five layers – three from the can end and two from the can body – are compressed and tightly ironed to create a hermetic seal.

One crucial detail: since cans of sweetened condensed milk do not undergo sterilisation after sealing, the filling environment must be exceptionally clean. Any microbial contamination introduced during packaging directly affects the product’s shelf life and safety.

Sanitary conditions during condensed milk canning 🔗

Maintaining strict hygiene during the filling and sealing of condensed milk cans is essential. Here are the key practices followed in well-managed operations:

The filling and sealing area should be fully enclosed, with only filtered air circulating to keep out atmospheric dust and dirt. All filling machines and accessories must be thoroughly washed and sanitised before each production run begins. The cans and lids, as they move towards the filler, must be sterilised – typically by passing them under or over a battery of gas jets. Personnel operating the equipment are also required to follow sanitary habits rigorously.

It is important to fill each can as fully as possible to exclude as much air as practical, and then seal the can promptly. Residual air inside the container can promote oxidation, leading to off-flavours and reduced shelf life over time.

Packaging of evaporated milk 🔗

Evaporated milk packaging follows a distinctly different approach compared to condensed milk. Because evaporated milk has no added sugar to act as a preservative, the product must be sterilised inside its sealed container. This means the packaging and sterilisation steps are closely linked, and the containers must be able to withstand high temperatures and pressures.

Can filling methods 🔗

Two main types of can-filling systems are used for evaporated milk:

Vent-hole type: In this method, the concentrated milk is filled through a small aperture (approximately 3 mm or 1/8 inch in diameter) in the can. After filling, the cans are sealed immediately. The opening is typically soldered shut by a mechanical device, though hand soldering may be used for smaller-scale operations. Speed is critical here – the cans must be filled and sealed as fast as possible to minimise the risk of contamination.

Open-top (sanitary) type: In this more modern approach, open cans with one end already seamed are used. The concentrated milk is filled into the open top of the can, and then the other end is seamed shut by an automatic seaming machine. This method allows for faster processing and is widely used in larger factories.

After sealing, every can is tested for leaks. The standard method involves plunging the sealed cans into a hot water tank. If any tin rises to the surface or releases air bubbles, it is immediately discarded as unfit for sterilisation. Modern sealing lines operate at high speeds, processing a large number of cans per minute.

In-container sterilisation 🔗

Once sealed and tested, evaporated milk cans proceed to sterilisation. The objective is to destroy all bacteria, spores, and enzymes, making the product shelf-stable without refrigeration. According to a US patent on evaporated milk sterilisation, the process typically involves subjecting sealed cans to temperatures of around 116-118°C (approximately 240°F) for about 15 minutes.

Two sterilisation systems are commonly used:

Batch sterilisation is suitable for small-scale operations and can handle cans of various sizes. The filled cans are placed in racks, loaded into a steam-tight autoclave, and rotated at 6-12 revolutions per minute throughout the process. After the required heating time, steam is shut off and the cans are cooled to 25-30°C using water sprays or immersion in cold water.

Continuous sterilisation is designed for large-scale production. The system consists of multiple compartments maintained at different temperatures and pressures. Cans roll through these chambers via a spiral track, ensuring uniform heat distribution to each container. The rolling motion replaces the mechanical agitation provided in batch systems. Both methods maintain the cans at sterilisation temperature for approximately 15 minutes before moving them into a cooling section.

After sterilisation, the cans are cooled and then often passed through an oscillating or shaking machine. This breaks up any curd or lumps that may have formed during heat treatment, restoring a smooth, homogeneous texture. Excessive shaking is avoided because it can decrease the product’s viscosity.

Packaging materials and their properties 🔗

The most common packaging material for both condensed and evaporated milk is tin-plated steel. Tin plating provides corrosion resistance and a food-safe surface, while the steel underneath gives the can structural strength – especially important for evaporated milk cans that must survive high-temperature sterilisation. Some manufacturers also use aluminium cans, which are lighter and resist corrosion well.

As noted by the FAO, the choice of packaging material has always been tied to the type of heat treatment the product receives. In-container sterilised products require packaging that can form and maintain a hermetic seal under extreme conditions. Internal can surfaces are often coated with food-grade lacquers or synthetic polymeric resins to prevent the metal from reacting with the milk, which could cause off-flavours or discolouration.

In recent years, some manufacturers have begun offering sweetened condensed milk in aseptic paperboard cartons, sachets, and tubes, especially for consumer convenience. However, for evaporated milk – which requires in-container sterilisation – metal cans remain the dominant choice because alternatives struggle to withstand the temperatures and pressures involved.

Modern filling equipment and automation 🔗

Today’s dairy packaging lines are highly automated. Industrial filling machines can handle hundreds of cans per minute with precision dosing, automated seaming, leak detection, labelling, and case packing all occurring in sequence. For example, automated end-of-line systems for condensed milk cans in large facilities can operate at speeds of up to 400 cans per minute, incorporating labelling, case erecting, case packing, and sealing in a continuous flow.

Filling machines used in dairy applications are built to meet stringent sanitary design standards (such as 3-A Sanitary Standards in the United States and EHEDG guidelines in Europe). These machines feature stainless steel construction, non-contact filling nozzles to prevent cross-contamination, and clean-in-place (CIP) systems that allow thorough sanitisation between production runs without disassembly.

Key differences between condensed and evaporated milk packaging 🔗

To summarise the main distinctions: sweetened condensed milk relies on its high sugar content for preservation and does not need post-packaging sterilisation, so it can be packed in both barrels (for bulk use) and cans (for retail). The emphasis is on maintaining a clean, enclosed filling environment since there is no further kill step after sealing. Evaporated milk, lacking added sugar, must be sterilised inside its sealed container. This means only containers that can tolerate high heat and pressure – primarily metal cans – are suitable. The sealing must be robust enough to withstand sterilisation, and every can is tested for integrity before heat treatment begins.

Both products benefit from being stored at cool temperatures (ideally 10-15°C) to maintain quality over their shelf life, which can extend to 18-24 months when packaging and storage conditions are properly managed.

What do you think? With newer packaging options like aseptic cartons and flexible pouches entering the market, do you think traditional metal cans will continue to dominate for concentrated milk products? How important is packaging innovation for extending shelf life while also reducing environmental impact in the dairy industry?

References

1. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/sterilized-milk
2. http://dairy-technology.blogspot.com/2014/01/packaging.html
3. https://egyankosh.ac.in/bitstream/123456789/9538/1/Unit-11.pdf
4. https://www.bwfillingclosing.com/products/can-seamers-angelus
5. http://dairy-technology.blogspot.com/2014/01/manufacture-of-evaporated-milk.html
6. https://patents.google.com/patent/US3112205A/en
7. https://www.fao.org/4/X6511e/X6511E01.htm
8. https://fruitprocessingmachine.com/portfolio-items/condensed-milk-processing-line/
9. https://www.clearpack.com/blog-post/end-of-line-packaging-of-condensed-milk-can