Packaging Solutions for Malted Milk Foods

Malted milk foods – products made from milk solids, malt extract, and cereal grain flour – are among the most moisture-sensitive items in the dairy industry. Their packaging is not a mere afterthought; it is a critical step that determines whether the product reaches consumers in perfect condition or turns into a sticky, clumped, unusable mess. Understanding why and how these products must be packaged gives valuable insight into the science behind shelf-stable dairy foods.

Why malted milk foods are so vulnerable to moisture 🔗

The term hygroscopic describes a substance that readily absorbs moisture from the surrounding air. Malted milk foods are extremely hygroscopic, primarily because of their composition. During manufacturing, the barley malt’s diastatic enzymes convert starch into sugars, and additional milk sugars (lactose) are present in a non-crystalline, amorphous state. These process-converted and added sugars have a strong affinity for water molecules. When exposed to even moderately humid air, the powder particles begin absorbing moisture almost immediately.

This is not a minor concern. The water activity (aw) of properly dried malted milk food is typically below 0.6, a level that inhibits most microbial growth. However, once moisture creeps in, water activity rises, and the product becomes vulnerable to bacteria, yeasts, and moulds. Beyond microbial risks, moisture absorption causes physical changes – the powder becomes sticky, soft, and forms hard clumps that are impossible to dissolve properly. The flavour also deteriorates as unwanted chemical reactions, including browning and lipid oxidation, accelerate in the presence of moisture.

The role of low-humidity environments in packaging 🔗

Because malted milk food is so eager to absorb water from the air, the packaging process itself must take place in a controlled, low-humidity environment. Manufacturers typically use dehumidification systems in their packaging areas to keep relative humidity well below safe thresholds. According to industry guidelines for dried dairy products, packaging facilities generally aim to maintain relative humidity levels that minimise vapour transmission into the product during the brief exposure period between drying and sealing.

If the air in the packaging room is too humid, the malted milk powder will start absorbing moisture before the container is even sealed. This defeats the purpose of using moisture-proof packaging, since the product itself would already carry excess moisture going into the container. That trapped moisture then leads to caking, stickiness, and accelerated spoilage inside the sealed package.

Cooling before packaging 🔗

An often-overlooked but essential step is cooling the product to room temperature before packaging. Malted milk food is typically dried at high temperatures – either in vacuum tray dryers or spray dryers – and may still be warm when it comes off the production line. Packing warm powder into a sealed container creates condensation on the inner walls of the packaging as the product cools. This condensation introduces free moisture directly onto the powder surface, triggering the exact problems the packaging is designed to prevent. For this reason, the dried product is first cooled in an air-conditioned room to avoid moisture pick-up, then scrapped off trays, milled into fine powder, and only then moved to the packaging line.

Glass bottles with screw-type metal lids 🔗

The traditional and one of the most effective packaging solutions for malted milk foods is the glass bottle fitted with a screw-type metal lid. This combination has been favoured for decades, and for good reason.

Why glass works so well 🔗

Glass is an inorganic, non-porous, chemically inert material. It provides a complete barrier against moisture, oxygen, and odours. Unlike many plastic materials that allow trace amounts of water vapour to permeate through their walls over time, glass blocks moisture transmission entirely. Research published in ScienceDirect comparing glass, PET, and HDPE containers confirmed that glass offers the highest moisture and oxygen barrier properties among common packaging materials.

Glass also does not react chemically with the malted milk food, so there is no risk of off-flavours, tainting, or leaching of substances into the product. The transparency of glass allows both manufacturers and consumers to visually inspect the product’s condition – checking for colour changes, clumping, or other signs of deterioration without opening the container.

The importance of the screw-type metal lid 🔗

The glass bottle alone is not enough. The closure is equally critical. Screw-type metal lids create a tight, hermetic seal when properly applied. The threading mechanism ensures consistent compression between the lid and the bottle finish, preventing air and moisture from entering through the closure. Many metal lids incorporate a sealing compound or liner (often made of expanded polyethylene or other food-grade materials) that fills microscopic gaps between the lid and bottle rim, further enhancing the seal’s integrity.

A study on closure systems noted that the sealing efficiency depends on proper application torque – the lid must be tightened to the correct specification during manufacturing to guarantee an airtight seal. If under-tightened, moisture can seep in; if over-tightened, the closure may deform and compromise the seal over time.

Other moisture-impervious containers 🔗

While glass bottles remain a popular choice, manufacturers also use several alternative packaging formats depending on cost considerations, scale of production, and market requirements. The key requirement for any alternative remains the same: it must be virtually impervious to moisture.

Metal cans 🔗

Metal containers made from tinplate or aluminium offer excellent protection against moisture, oxygen, and light. They can be hermetically sealed and are widely used for dried dairy products. Some manufacturers pack malted milk food under vacuum or in a nitrogen atmosphere inside metal cans, which removes oxygen from the headspace and further extends shelf life. The main drawback of metal cans is their susceptibility to corrosion if exposed to temperature fluctuations that cause condensation, though modern lacquer coatings and aluminium construction have largely addressed this issue.

Laminated flexible packaging 🔗

Modern laminated pouches and sachets use multiple layers of different materials – typically a combination of polyethylene, aluminium foil, and polyester – to create effective moisture barriers. Aluminium foil in these laminates provides near-total protection against moisture and oxygen permeation. These multi-layer barrier structures are lighter and cheaper to transport than glass, making them an increasingly popular option for refill packs and single-serve portions. However, they must be handled carefully to avoid punctures or tears that would compromise the barrier.

High-density plastic containers 🔗

Food-grade plastic jars made from high-density polyethylene (HDPE) or polypropylene (PP) are sometimes used, particularly for consumer-sized portions. While these materials offer reasonable moisture resistance and are lightweight and shatter-proof, their barrier properties are not as absolute as glass or metal. For highly hygroscopic products like malted milk food, plastic containers often require additional barrier layers or desiccant sachets inside to maintain adequate protection during the entire shelf life.

What happens when packaging fails 🔗

When malted milk food absorbs moisture due to inadequate packaging, the consequences are predictable and problematic. The first visible sign is clumping and caking – the free-flowing powder sticks together in hard lumps. This happens because dissolved sugars on the particle surfaces act as a glue, binding particles together. The product’s texture becomes soft and sticky, making it difficult to scoop, measure, or dissolve properly.

Beyond texture issues, moisture absorption promotes Maillard browning – a chemical reaction between sugars and amino acids that darkens the product and produces off-flavours. The fat content in malted milk food is also susceptible to oxidation, which creates rancid, unpleasant tastes. Products with higher lactose levels are particularly prone to stickiness, caking, lactose crystallisation, and increased browning during storage if moisture barriers are breached.

In serious cases, elevated moisture levels can push the water activity above safe thresholds, enabling microbial growth – including moulds that may produce harmful mycotoxins. At this point, the product is not just unappetising but potentially unsafe for consumption.

Quality control during the packaging process 🔗

Effective packaging of malted milk foods requires more than just choosing the right container. The entire packaging process must be carefully monitored and controlled.

Environmental monitoring 🔗

Temperature and humidity in the packaging area must be continuously tracked. Any spike in humidity – from weather changes, equipment malfunction, or inadequate HVAC systems – can compromise an entire production batch. Most modern facilities use automated sensors and alarms to alert operators when conditions drift outside acceptable ranges.

Seal integrity testing 🔗

Every sealed container must maintain its barrier properties throughout the product’s intended shelf life. Manufacturers regularly test seal integrity through methods such as vacuum decay testing, pressure testing, and visual inspection. For gas-packed metal cans, headspace gas analysis confirms that oxygen levels remain below the target (typically less than 2%) and that the inert atmosphere is intact.

Compliance with food safety regulations 🔗

In India, the Food Safety and Standards Authority of India (FSSAI) sets specific labelling and packaging requirements for malted milk food products. These regulations mandate that packaging materials must be food-grade and safe for their intended use. They also require specific labelling declarations, including details about added colouring matter, artificial sweeteners, and sugar content, ensuring consumers have clear information about the product they are purchasing.

Storage conditions after packaging 🔗

Even the best packaging cannot compensate for poor storage practices. Once packaged, malted milk foods should be stored in cool, dry warehouses away from direct sunlight. Ideal storage conditions typically mean temperatures below 25°C and relative humidity below 65%. Temperature fluctuations during storage and transportation are particularly dangerous because they can cause condensation inside the packaging, introducing moisture directly onto the product surface even when the seal is intact.

Distribution logistics must also account for climate conditions, especially in tropical and subtropical regions where ambient humidity is naturally high. Proper palletising, covered transport, and climate-controlled warehousing all contribute to maintaining the integrity of the packaged product from factory to retail shelf.

Emerging trends in malted milk food packaging 🔗

The packaging industry continues to evolve, and several trends are relevant to malted milk foods. Modified atmosphere packaging (MAP), which replaces the air inside a container with nitrogen or a nitrogen-carbon dioxide mixture, is gaining traction for dried dairy products. This approach not only removes moisture-laden air but also eliminates oxygen, slowing oxidation and extending shelf life significantly.

There is also growing interest in recyclable high-barrier films that can replace traditional multi-material laminates containing aluminium foil. These newer materials aim to offer comparable moisture protection while being easier to recycle, addressing the dairy industry’s increasing focus on sustainability.

Additionally, the shift from traditional vacuum tray drying to spray drying for malted milk food production produces powder with improved physical characteristics like better dispersibility and wettability. This change in the product’s particle structure may also influence future packaging requirements, as spray-dried powders may behave differently in terms of moisture absorption compared to conventionally dried products.

What do you think? How might the push for sustainable, recyclable packaging materials affect the shelf life and quality of hygroscopic products like malted milk foods? And with India’s growing demand for malt-based beverages, what role should regulatory bodies like FSSAI play in setting stricter packaging standards for these products?

References

1. http://dairy-technology.blogspot.com/2014/01/malted-milk-foods.html
2. https://www.dairyglobalnutrition.org/safety-and-quality/shelf-life-and-packaging
3. https://www.ift.org/news-and-publications/food-technology-magazine/issues/2021/september/columns/packaging-controlling-moisture
4. https://www.sciencedirect.com/science/article/abs/pii/S1773224722002404
5. https://www.newfoodmagazine.com/article/27263/dairy-packaging-materials-and-methods/
6. https://www.honokage.com/milk-powder-packaging-material-an-in-depth-analysis/
7. https://fssai.gov.in/upload/uploadfiles/files/Compendium_Packaging_Labelling_Regulations_05_06_2022.pdf
8. https://www.ti-films.com/case-studies/recyclable-milk-powder-packaging-with-ultra-high-barrier-properties/