As said in my previous article today we will have a look at three new pasteurisation/sterilisation techniques for ready meals. These techniques are all related to microwaving, but in such a way that the results, taste, texture and nutrient value, are far superior to the old autoclave sterilisation technique, used in the past for ready-to-eat meals. In all three techniques steam is used as a by-line.
That’s different with the fourth example in which steaming is the main cooking source, as it is a newly developed disposable food steamer from Russia. I suppose that I don’t have to explain that steaming raw food is the best way of preparing a meal, in terms of taste, texture and nutrient value. It certainly is the first step into a world of “steaming packages”.
We start with the Swedish Gooh meals.
A development from MicVac, in cooperation with SealPac, allows Sweden’s Lantmännen Gooh to market an in-pack microwave cooking and pasteurisation concept for its ready-to-eat meals. It provides a refrigerated shelf life of at least 30 days at 8ºC.
This new method of preparing food involves a thermoformed tray filled with raw food ingredients, meat, poultry, vegetables, and certain partially pre-cooked ingredients such as potatoes. The filled polypropylene tray is topped and heat sealed with a peelable PA/PP flexible film.
Just before the lidding material is applied, a small hole is punched in the lidstock, while over the hole a special MicVac valve is applied.
Filled, lidded, hole-punched and “valvelized” the trays are sent through a microwave tunnel, in which the contents are cooked for 4 to 10 minutes depending on the size of the particulates in the tray. During this cooking process, the MicVac valve opens to release the internal pressure created as the food releases steam. The patented valve can open and close multiple times.
The seal of the lidstock to the tray is strong enough to withstand the internal pressure during pasteurisation and heating up in the consumer’s microwave yet it remains easy to peel away when the heated food comes out of the microwave.
The final result is a cooked, pasteurised, and vacuum packaged ready meal. For more detailed information about this new pasteurisation process and the packaging read the Packaging World Magazine article with video written by Pat Reynolds: “Microwave pasteurization puts ready meals where consumers want them”
The second example is an evolutionary step further into the technology as described above.
Variable Heating Steaming
Variable Heating Steaming was the first name the inventors gave to this new technique, then it changed in Steam Cuisine, to finally end up as: microwave-shielding technology.
Shieltronics microwave-shielding technology makes it possible to control the intensity of microwaves in a microwave oven so that foods requiring less microwave energy than others can all be prepared in one convenient cooking cycle lasting four to six minutes.
To achieve this, the packaging has a special structure. It’s a two-compartment injection-moulded PP-tray that is filled with vegetables in one compartment and raw or partially cooked fish, chicken, or meat in the other.
The LDPE lidding film is laser perforated in three areas. Two sets of perforations over the vegetable compartment, while the third set is perforated over the protein compartment. The protein compartment is evacuated and back-flushed with a gas mix that prolongs refrigerated shelf life to eight or nine days and the perforated lidstock is heat sealed on the rim of the tray and the wall that separates the two compartments. The end result is an MAP compartment for protein and a separate compartment for vegetables.
To conclude the process two LDPE pressure-sensitive labels about 10 mm in diameter are applied over one perforation of the vegetable compartment and one over the perforation of the protein compartment. These labels function as valves and open slightly to release some of the internal pressure that builds up when the consumer cooks the meal in the microwave oven. The valve on the protein compartment also ensures that the modified atmosphere environment is maintained.
One of the perforations on the vegetable compartment remains uncovered, to allow the fresh vegetables to respire: oxygen in, carbon dioxide out. Without this controlled exchange of gases, the vegetables would spoil fast.
This technology lets dissimilar foods requiring very different cooking times in a single package that can be conveniently cooked in the microwave without requiring the consumer to cook them separately.
The third example is a completely different set-up.
Frozen-food tray incorporating two innovative technologies
The new frozen-food tray, developed by Graphic Packaging Intl. for ConAgra Foods has two innovative technologies incorporated. DesignerWare is a paperboard/plastic hybrid, and MicroRite, provides shielding and even-heating benefits to frozen meals heated in the microwave.
The paperboard body of the DesignerWare paperboard/plastic hybrid tray replaces up to 55% of the non-renewable plastic with renewable paperboard. The injection-moulded frame provides additional stiffness, impact resistance and the possibility for a high-barrier package for chilled and non-food applications.
For the MicroRite technology the trays are laminated with a polyester film of thin patterned aluminium. The patterned aluminium is used to harness and control the microwave energy, as the MicroRite technology redistributes the microwave energy via a selective aluminium patterning, channelling it deeper into the frozen food for faster more even heating. The technology, according to the company, provides shielding and even-heating benefits to frozen meals, as it manages the available microwave energy, reducing cooking time, dehydration, overcooked edges and unheated centres.
The company claims that the laminated trays also perform well in conventional ovens.
My last example is the steaming packaging from Russia.
During the 22nd international World Food (Весь мир питания) exhibition in Moscow last September Aleksey Parovarov presented his newest invention the “disposal steamer”.
The disposable steamer is made of two compartments. The upper contains a frozen prepared product to be cooked with steam, while in the lower the consumer pours water prior to cooking the product.
After adding water to the steamer (250 ml right over the frozen prepared product) the consumer places the packaging on a stove (gas or electric), on low fire. The cooking process takes 5 – 35 minutes depending on the ingredients from which the prepared frozen product is made.
During heating steam flows from the lower to the upper compartment through openings in a perforated plate, which ensures careful and uniform cooking of the prepared product.
The disposable steamer packaging is made of aluminium foil with a plastic window allowing the consumer to monitor the cooking process.
According to the inventor, the production costs virtually equal that of similar cardboard packaging and don’t have a substantial impact on the price of the end product. The steamer size is meant for approximately 500 g of prepared product or 8 standard size dumplings.
And what about the future?
The Institute of Food Technologists recently issued a Scientific Status Summary on the latest innovations in food packaging materials. They indicated that “as consumers continue to spend heavily on foodservice products, the role of packaging in ensuring food safety and providing convenience can only increase.
And there are new packaging technologies in the pipe-line. One of them, not on the market yet, is Culidish, a new wave in culinary food preparation.
The CuliDish design allows simultaneous microwave heating of food that requires high heat and food that does not (such as salads) in the same tray. This technology has the extraordinary property of being able to control the amount of microwave energy that can reach the different meal components, as a result of which it is possible to prepare salads, vegetables, sauces and meat/fish in the microwave at the same time, on a single dish, bringing each component to exactly the desired temperature.
The control over the microwaves is achieved by means of a shielding technology. During the production process (injection moulded/in-mould labelling) a specially engineered label is incorporated into the wall of the food packaging containers. Shieltronics Meta-Grid flexible multi-layer foils then control the microwave energy intensity explicitly per compartment ( 0 – 100%), ensuring that each meal component will reach its own optimal temperature.
Such innovations in the area of heat and heat retention will reduce the food safety risks associated with improper cooking. Food consumers prepare and eat only 60% of meals at home and 20% of consumers eat while in-transit to another location. As a consequence, many of the innovations in foodservice packaging are accommodating ready meals eaten in transit and multi-component meals.