Self-Heating Packaging With Built-In Microwave Device

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It’s always very helpful when you want to write an article about a specific issue and you don’t know anything about the technique behind it. You don’t feel restricted in your ideas by knowledge, you don’t have prejudices, and you never will say “That can’t be done”, when you only are familiar with the household application of the technique. That’s the case with microwaving.

Referring to the Symposium of the International Microwave Power Institute held in New Orleans last month, I want to write today about “Self-heating Packagng With Built-In Microwave Device”.

And coming back to that “helpful”-remark I made, I have to admit that I’m not at all interested in the pure technique of microwaving (that’s for the specialists), but solely in the application of the microwaving technique in packaging. To install microwave technique into packaging, I don’t need to know how it works, I only want (after some logical thinking) to present some packaging ideas in which incorporating microwaving technique might work after some (without doubt intense) development by the specialists.

Recently we have seen some revolutionary developments in materials, which elevate the microwaveable packaging onto a new level. I wrote about some of these new developments in my previous article.
Today we will have a look at the outdoor market, the let’s call it rough-terrain entertainment, where even the basic facilities are absent. We talk about packaging convenience fot the expanding consumer interest in hiking, mountaineering, sailing, biking and more of those extreme outdoor activities and maybe even festivals.

A growing number of self-heating packages is trying to infiltrate that expanding outdoor market. But I’m convinced that the manufacturers of self-heating packaging are keeping alive the wrong technique. The exothermic chemical reaction, which is the heart of the self-heating packaging, is a result of lime reacting with water generating a substantial heat output. However this self-heating source is out-dated, incorporates some serious risks, and isn’t offering the required results or not even suitable for solid food. Furthermore it makes for weighty beverage cans. Although the self-heating technique of HeatGenie comes from a solid fuel source, it still has the same disadvantages as mentioned above. For more about this self-heating technique read my article here, here and here.

I think we have to look into more sophisticated techniques for self-heating solid food, such as ready meals and snacks, in a rough-terrain environment. Furthermore it’s of great importance that differentiation in heating intensity (compartmental heating) can be realised. We have seen this importance described in several of my articles: “What’s Going On In Packaging For Ready Meals” (Click here and here).

I can’t see (but who am I) a simple solution for compartmental heating, if this heating is a result of a chemical reaction. The heating is an even in the whole packaging and even worse it’s almost certain that the (short time) intensity of the heating results in partially burned and blackened food parcels, making the complete ready meal inedible.

No, the self-heating techniques being on the market aren’t suitable. I was thinking into another direction. A tentative approach is given by an American inventor, who designed the portable microwave, about which I wrote in my article: “Ready Meals And The Onda Portable Microwave”

The portable microwave of course is a brilliant development. However, I’m afraid it will not work out as a success in the market place, simply because it requires a more or less standardised consumer packaging. This type of standardisation is very complex and I don’t see the willingness of the consumer goods companies to reign in their fancy ideas that are supposed to conquer the market.

Consequently we have to find a more flexible solution. But keep the portable microwave in mind, because it will be at the basis in my “thinking-process” about self-heating ready meals.

Microwave heating proves to be portable. Let’s analyse the before mentioned Onda Portable Microwave. The inventor, Matthew Schwartz, explains the working of the Onda as follows:
“The working is simple. Pre-prepared meals are placed in compatible food containers. When the device is attached to the dish, they seal together, the aluminium contained within the interior of the handheld device, creates a circuit connection when the seal of the packaging is broken and the enclosed food container acts as the cooking chamber which contains all of the microwaves safely inside. Power-paper batteries produce steady and eco-friendly power for efficient cooking and allow it to be used virtually anywhere”.

Correctly the inventor included some extra functions in the Onda, to secure an overall application for whatever ready-meal is connected to the device. As I intend to incorporate the microwave device into a specific packaging of a ready-meal, we can skip all the extra and additional functions and simplify the device for that specific ready-meal. Just one pre-set temperature, one pre-set time and consequently one pre-defined energy output.
This position also simplifies the choice and the dimensions of the necessary one-way paperboard batteries.

Furthermore we have to take a look at the packaging material. The description of the Onda Portable tells us that “the aluminium contained within the interior of the handheld device, creates a circuit connection when the seal of the packaging is broken and the enclosed food container acts as the cooking chamber which contains all of the microwaves safely inside”.

We have seen various aluminium contained ready-meal trays, particularly the one of ConAgra Foods (see photo) of which not only the hybrid paperboard/plastic material is able to stand microwave heat, but the incorporated MicroRite technology, which redistributes the energy via a selective aluminium pattern, can be used as the ‘circuit connection’ as mentioned in the description of the Onda.

Of course there are other materials for ready-meal trays suitable for incorporating a microwave device. I just want to draw attention to the Ahlstrom NatureMold, of which I wrote in my article: “Innovations in Food Trays”.

NatureMold is a fibre based tray laminated with a Genuine Vegetal Parchment and can in my opinion easily hold a thin aluminium pattern as circuit connection.

What’s left for us to solve. We have been talking about compartments to ensure partial heating, better call it ‘tailor-made’ heating, of the ready-meal.
In my article: “What’s Going On In Packaging For Ready Meals (Part 02)” I explained the Shieltronics microwave-shielding technology 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.
This is achieved by creating compartments. 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 Shieltronics technology uses PP as material for the tray and perforated lidding film to cover the protein and vegetable compartments. This, of course, can’t be copied by a microwave packaging as proposed in this article, as the microwave energy is incorporated in the packaging and for Shieltronics it’s the extern microwave which has to be controlled. But nevertheless it has to set us thinking. Include into that thinking-process the material for microwaveable packaging as described in my article: “Developments In Microwaveable Food Packaging”.

In that article I write about the development of the Heat Fresh Pouch designed by Hillshire Brands. The main characteristic of this packaging design is, that it offers a moisture-equilibrating, self-venting, absorbent packaging for one-step microwave heating, so that the consumer gets the same texture on the bottom as on the top. The nonwoven film is the absorbent component of the packaging.

The interesting part of this design is that during heating, moisture created by the heat cycle rises to the top of the packaging, rolls down the sides, and is absorbed by the non-forming film. At the same time, pressure is created within the packaging to drive heat into the core for controlled, even heating of meats, cheeses, and other components. The packaging is also designed to self-vent so that it doesn’t burst during microwaving

This must be a perfect material for compartmentalising a multi-ingredient ready-meal packaging.

So, now we are at the end. Don’t you think that when we put all the items, I mentioned in this article, into a tumbler and shake a few times, that a packaging for ready-meals with an incorporated microwave device rolls out? As a matter of fact we only need some simple electronic parts and the correct choice in packaging material. Let’s see what the specialists have to say.

One response to “Self-Heating Packaging With Built-In Microwave Device

  1. Thank you for the comparison and the nice explanation. I was always looking for something like this but did not get before. Your point on portable microwave is valid but I guess soon we will also have much more flexible portable microwaves

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