Packaging Heated Products Successfully

With a growing trend for packaging baked products, including those freshly baked, temperature is the prime indicator to optimize everything from the packaging process to ultimately the shelf life before consumption. In a recent interview, Andreas Schildknecht, senior product manager Robotics/industry manager Bakery at Syntegon Technology, explained the challenges and priorities manufacturers should consider when packaging heated goods as well as products that will be heated in their packaging.

If the temperature is too low, the product has already begun to dry and becomes brittle, which, in turn, leads to faster staling. If the temperature is too high when packaging baked goods, they have not been allowed to cool and dry enough, and the excessive moisture will lead to condensation, softening of the crumb and loss of product integrity when slicing.

The challenge in bakery is to keep the freshly packaged products looking fresh, smelling fresh and tasting fresh. Handling and packaging must be arranged in such a way that it keeps delicate bakery products crunchy and tasty throughout the whole manufacturing and supply chain.

The conditions inside a hermetically sealed pack can only be at an optimum if products enter with a core temperature below 5°C during the packaging process. “This helps to create an ideal atmosphere with low levels of humidity, maximizing shelf-life, and reducing the growth of mold,” Andreas Schildknecht explains.

To ensure consistency in packaging, the production environment must be maintained stable at all times, the specialist stresses. “Manufacturers need to monitor their facilities constantly. The prevailing humidity and temperature levels directly influence the moisture levels and product temperature inside each pack,” he illustrates. Additional factors, such as exposure to sunlight, can also impact on product quality. “Surfaces have to be easy to clean and the machines should be designed in a way that prevents the accumulation of product residue and dirt. The machinery also has to be robust enough to endure relevant cleaning methods,” Schildknecht says.

Technology Requirements

The bakery industry works with the broadest range of product variety, format range and pack style complexity. As a result, format flexibility and fast changeovers are key to overall equipment effectiveness. “In terms of wrapping equipment, the maximum film width defines the machine’s format range. For wrapping pizzas or large cake products, this often requires a film width of 700mm or more,” says the specialist. Robotic solutions, vision inspection systems and scalable, programmable feeding systems, such as XTS linear motor technology, offer maximum flexibility and gentle handling. “Automated changeovers minimize downtime and ensure vertical start-ups. Being able to adjust the entire system to the required speed differences  – from the oven to the case packer – and optimize all interfaces maximizes efficiency and reduces food waste,” highlights Schildknecht.

Packaging Different Product Categories

In general, flexible primary packaging is ideal for bakery products. Depending on the product size and pack style, manufacturers choose horizontal and vertical form fill and seal (VFFS) equipment for flow wraps and bags. VFFS bags are common in bakery for more robust products, that are fed into bags randomly by a check-weigher or counting device. Individual flow-wrapping, on the other hand, is more suitable for delicate products, like cupcakes, muffins or donuts.

Bread often goes through a slicing process and is then packed in pre-made clipped bags, ranging from 200 to 1,000g. “Due to the size of the packs and presentation on the shelf, case packing is preferred for shipping and shelf-ready packaging. In North America in particular, where manual loading is being replaced by flexible and hygienic robotic solutions, we see a lot of clamshell packaging,” he observes.

Shelf-life Optimization

Different bakery products require different levels of moisture to maintain a long shelf-life. Throughout the product’s shelf-life, the moisture level has to remain constant. Modified atmosphere packaging (MAP) technologies and proper storage at steady temperature levels help to prevent condensation.

Depending on the product, different solutions and strategies are available to extend their shelf-life. An important driver is reducing food waste. This can mean offering just the right amount of products to the various end-consumer groups, from single-households to families. “Portion packs can help minimize food waste: single unit packaging within a multi-pack keeps products fresh for longer since consumers can portion the product more easily,” Syntegon’s specialist tells us. Added functionalities, such as easy opening and closing features for resealable packs, increase the product’s shelf-life.

Moreover, modified atmosphere packaging (MAP) technologies, like gas-flushing with CO2 or nitrogen, can also improve shelf-life significantly, he adds. “Some products require alcohol or saline solution spraying to protect the products further. Cream-filled products in particular often require an additional barrier that protects them from light. Secondary packaging solutions (such as top-load cartooning) offer additional protection throughout the supply chain.”

Final Preparation of Packaged Products

Special considerations should be taken into account when packaging goods that will be heated (final baking or heating) in the packaging, because there is no “one-size-fits-all” solution in this scenario. Manufacturers have to take their products and consumers into consideration when choosing the right packaging material and pack style.

The most relevant factor, in this case, is the heat resistance of the packaging material. “Packaging films have to be sealable using heat, while still being able to resist enough heat for final baking. During the heating and final baking process, in particular, food safety is key. The packaging material has to maintain its physical characteristics, such as stiffness, transparency and taste, throughout the process. Lastly, the consumer needs to be able to open the pack easily and safely once heated or baked,” illustrates the specialist.

The packaging industry offers several solutions and different pack styles like bottles, clamshells, bags, pouches, even sustainable materials. He weighs in on common materials, including Polyethylen (PE): “Different from Vinylen (PVC), Polyethylen does not emit any pollutants through incineration or bio-degrading processes that could harm the environment. The thermoplastic material is multi-recyclable, fusible and reformable and malleable again.  Polyethylen does not lose its characteristics in a range of -60 to +85°C. Looking at the highest acceptable temperature level, it becomes clear that PE can only be used for warming up, not baking. Studies also show some emission of micro-plastics due to embrittlement or overheating, which may conflict with food-safety regulations.  Polyethylenterephthalat (PET)  also withstands oil, alcohol, weak acids and fat what is a big advantage when it comes to packaging food. It is often used for microwave trays.  Crystalline Polyethylene Terephthalate, short-name CPET is an inexpensive alternative to aluminum trays, allowing for a temperature range of -20 up to +220°C.” To meet the different requirements, many packaging material suppliers have developed solutions specifically for baking or microwaving. Some suppliers offer advanced material allowing for a temperature range of -40 up to +175°C, featuring vacuum packaging capabilities, ease-of-use and easy-opening features, extended shelf-life and shortening of baking times.

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