Self-Cooling Chocolate Packaging – Kraft invites people to join them in research …..

Kraft Foods invites industry, scientists, and inventors to find a packaging technology that will protect chocolate bars from melting. It may surprise everybody that Kraft comes up with an innovation request which certainly will increase the material price of the chocolate packaging, after the company recently made a change for Milka chocolate bars from an aluminium foil wrapper inside a paper envelope to a one-layer, laminated, oriented polypropylene flow pack with a cold sealant, reducing packaging material by 60%.

Every chocolate lover knows the problem and although many a company has developed a new chocolate packaging in the past, nobody is addressing the problem of melting chocolate.

Kraft Foods, one of the world’s largest manufacturers of chocolate after its recent takeover of Cadbury, said possible approaches, minimising melting when the temperature ranges from 24 to 40°C, may include, but are not limited to, novel insulating materials, phase change materials, thin film approaches, active packaging technologies that are triggered by temperature or light, and novel cooling or heat absorbing technologies.

Let’s have a look, with an open mind, at existing relevant technology which might, eventually in combination and intertwined, and with some extra research, develop into the required ‘cool pack’.

The last 10-15 years the packaging world has been littered with technological failures in search to fulfil the dream for single-serve self-cooling beverage containers.

Technological choices boil down to two, namely endothermic chemical reactions (endothermic (“within-heating”) describes a process in which the reaction absorbs energy from the surroundings in the form of heat) and heat pump technology using water vapour as the heat transfer fluid. Endothermic reactions tend to be weak; by contrast water evaporation can be a powerful cooling process.
Heat pump technology is finding commercial success in Italy where coffee beverages like Caldo Caldo, and Freddo Freddo employ the endothermic reaction between sodium thiosulphate pentahydrate and water.

Unfortunately a chocolate bar is no beverage can, it doesn’t have any space for a heat pump technology how miniaturised as it might be. A solution in an endothermic reaction is although far from realistic probably a valuable option for chocolate bars.

Nanotechnology is a method of controlling matter at near-atomic scales to produce unique or enhanced materials. Nanotechnology uses tiny particles, measuring one billionth of a metre (a human hair is 80,000 nanometres (nm) wide).
In the form of composite films, wafer-thin nano coatings of aluminium or aluminium oxide protect snacks or chocolate bars packed in them from oxygen, water vapour and flavour substances. Other applications include sensors to detect pathogens and toxins in food or registering environmental changes. For example, nanochips in smart inks used for food packaging could register warnings if the temperature of the package rises above certain programmed limits.

In March this year, Innovalight, a California-based company, secured a patent for highly efficient crystalline wafer solar cells with silicon ink, which is believed to have commercial packaging applications. Meanwhile, researchers at the Stanford University have developed a technique that can turn ordinary packaging paper into a battery by using enhanced, recycled inks made of carbon nanotubes and silver nanowires.

Thermochromic techniques
The thermochromic technique is based on special pigments in inks which change colour as the temperature rises or falls. They got famous when Skol, Coors, Grolsch among others introduced the ‘cool meter’ on their beer cans, using a thermochromic ink, which indicates when the beer inside is cold enough to drink. The ink, which begins to change colour at 11°C, changes back to the original colour when the beer becomes warmer.

Atomic Layer Deposition coating
Developed in Finland in the 1970s by VTT Technical Research Centre of Finland, the ALD (Atomic Layer Deposition) reactor is a device for the chemical composition of thin films. It can produce a film with the accuracy of one atomic layer. The basic materials of aluminium oxide coating are usually trimethyl aluminium and water.
By using ALD coating, different functions can be integrated in the packaging material, such as properties which prevent water, oxygen, humidity, fats and aromas from permeating the packaging, while it  protects the surface from stains and bacterial growth.

Printed electronics
Printed electronics is opening up fascinating new potential. One idea is to supply energy from printed batteries or solar cells. That is the key to animated images or advertising jingles, but might also be the key to trigger a cooling process.
Konarka’s photovoltaic technology can utilize a wider range of the light spectrum than conventional solar cells, visible and invisible light sources, not just sunlight, to generate power.
Photo-reactive materials can be printed or coated inexpensively onto flexible substrates using roll-to-roll manufacturing, similar to how newspaper is printed on large rolls of paper.
Made from semi-conducting polymers and nano-engineered materials, the printed active material, sandwiched between printed electrodes which are sandwiched between the substrate and the packaging material, absorbs photons to trigger the release of electrons which are then transported to create electricity.
The finished product is only 2-10 mils (50-250 μm) thick.

Phase change material
Phase-change material shifts from liquid to solid or vice versa at pre-set temperatures.
Entropy Solutions Inc, a thermal technology company, developed the Greenbox, which protects temperature-sensitive products like pharmaceuticals. They use a combination of phase change material (E-Packs), and Thermal-Lock panels, which offer unparalleled resistance to heat transfer, as nanotechnology creates torturous path through pores of carbon silica to slow transmission of heat or cold.

Ok, this sounds and actually is a bit bulky, as it was designed for shipping containers. But the technology is there and it’s worth to have a look at.

Insulation films
For on-the-go products that are best consumed hot or cold a new flexible packaging material has been developed with insulation in mind. The film, made from bi-oriented polypropylene, created by Innovia Films Inc. and sold under the name Rayotherm, holds promise for food and beverage packaging. In addition to keeping food hot or cold, packaging made from the film would insulate consumers’ hands from the temperature extremes of items such as ice cream, soup and hot beverages.

Applications for the film include formed packages, wrap-around labels, in-mould labels and thermoformed labels. According to the supplier, the film is compatible with sealing, printing, embossing, die cutting and machining.

We know that for cooling/heating we need energy. Let’s resume: With the thermochromic inks we can establish the moment we need cooling, it then triggers the energy supply of photovoltaic material, or any other nano or ALD coating. And now the cooling element. Maybe some form of an endothermic reaction is feasible or some miniscule thin phase change layer incorporated in the packaging film.
Complicated? Ahh, nobody said there is a simple solution. Costly? I doubt it, as long as you can incorporate it with the film, the demand of Kraft worldwide is so high that it is feasible that it can be manufactured at low cost.

I know the tender closed September 10, but I’m sure that when you come up with some revolutionary, but realistic idea or invention, the people at Kraft Foods will listen, because nobody has a ready answer.

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