Chilling out on the shelf

The latest European innovation for chilled ready meals is manufactured on a continuous production line and claims it can extend shelf life up to 45 days. If this seems a little hard to believe, then read on.

In the supermarket ready-meals section, the consumer has the choice between a fully frozen product or a chilled product. Presently, the chilled meal generally commands a premium consumer perception over the frozen range for several reasons:

• The freezing process can damage the product quality, for example, rendering crisp vegetables into a mush when reheated.
• The factory freezing process will dehydrate the meal, and storage in a domestic freezer will continue to dehydrate it. This affects the final quality and eating experience.
• The chilled product has greater visual appeal on the supermarket shelf than a frozen meal as its display appearance is identical to the reheated meal, and the packaging is generally designed to show this off.
• The chilled meal is perceived as fresh and healthy. That frozen dinner could be up to 12 months old!

The chilled product also commands a premium market price, and so its popularity amongst manufacturers is increasing.

The primary challenge for chilled ready-meals manufacturers is the limited shelf life of the product, requiring a flexible production process and slick logistics to optimise the time the product is present on supermarket shelves.

There are two main methods used exclusively to extend chilled meal shelf life and still retain that ‘just made’ appeal.

Methodology	Process	Shelf life of product
Pasteurisation	Heating up of product post production to ensure sterility	Up to 14 days
Modified atmosphere packaging (MAP)	Displacement of air in pack with CO2, nitrogen, or a mixture of both	Up to 10 days

For retailers, wastage rates and discounts are high due to the pressure to sell within the product’s limited shelf life and the inevitable loss of any product that remains unsold once it has passed its use-by date.

Innovation

There is now a process on the market which claims to extend the shelf life of these meals by 30-45 days (under industry-standard chilled storage conditions), while maintaining the quality of their pasteurised equivalents.

The technology was invented in Sweden by a company called Micvac. A range of ready-meals products using this process is already being manufactured and sold in one of Australia’s leading supermarket chains.

The Micvac Valve Unit.

Firstly, the Micvac process is designed to fully cook the product in the plant, by the use of a continuous industrial microwave tunnel, instead of alternatives such as a spiral oven. This renders segregated high-risk/low-risk divisions within the plant unnecessary, as the raw ingredients can be assembled into the tray. The tray is then sealed and the contents fully cooked within the microwave tunnel. All product leaving the plant has therefore been fully cooked in a sealed tray, and is sterile. The microwave oven provides a rapid and thorough cook within a small footprint, the cooking performance of which cannot be matched by a spiral oven.

It should be noted that some hydrated products such as rice and pasta require partial cooking prior to assembly due to the differing cooking characteristics of the components of the meal.

This is more than just another microwave cooking technology, the company says. The new element in this process is the patented Micvac one-way valve that is attached to the film that seals the top of every meal. This valve allows the cooking steam to escape from the pack during the rapid microwave cooking process and therefore prevents the pack from exploding. Once the meal is cooked, the valve closes during cooling to ensure the pack remains fully purged and no exterior air is allowed back in.

Ready-meal packaging with the Micvac Valve Unit.

The novel, multi-purpose nature of this valve allows it to serve, firstly, as described above in the initial cooking process, and then as a cooking tool for the consumer when they reheat the meal in their microwave oven.

Once heated, the Micvac valve emits a loud whistling noise to indicate that the meal is ready. This is due to the passage of hot steam through the valve exactly as it occurred during the factory cooking process.

Build it and they will come

Micvac’s innovation is smart in more ways than just how it cooks and reheats food. The company makes and supplies a number of the unique elements of this new technology, all of which can be implemented into any standard ready-meal manufacturing process. These features will be of great interest to the rest of the ready-meal industry.

The film that covers the meals and the valves are each supplied in roll form by Micvac. A purpose-built Micvac Valve Unit (MVU) module is integrated into an existing tray sealer and applies the valve and the seal while the sealer is running. Micvac manufactures the valves itself to ensure they all meet the required quality standards.

The microwave tunnels are supplied and supported by Micvac from its Swedish base. The special microwaveable Flextray trays are manufactured under licence at various sites but can be obtained through Micvac directly. Outside of these process particulars, any standard ready-meals plant would already have the necessary equipment in use to manufacture this product.

Conclusion

The appeal of chilled ready meals is their quality and authenticity to restaurant-quality food. There are other life-extending methodologies which will take the product life well beyond six months, such as deep freezing or retorting, but products preserved by these methods cannot match the fresh appeal of the chilled product and are proving hard to market to the consumer.

The growth area in the supermarket aisles is in fresh and chilled foods. This sector will grow significantly over the next five years and is predicted to outperform the overall growth in supermarket sales, displacing tinned and boxed foods from the shelves.

Retailers will be looking for ways to maximise their displays of chilled foods and reduce wastage in this high-margin sector. Extending shelf life while maintaining quality is the sure-fire way of ensuring a product ends up on consumers’ shopping lists.

*Martin Bevis is one of Wiley’s Senior Process Engineers and has worked on a range of food manufacturing projects in the United Kingdom, Europe and Australia.