Plastics ensure the cold chain remains unbroken
Cold chain: it affects us all !
The cold chain involves ensuring that refrigerated or frozen foods are constantly maintained at a low temperature, either positive or negative, depending on the case. This process enables the hygienic, nutritional and organoleptic qualities of products from the place of production to the kitchen. Why is it important to never break the chain? Simply because cold limits or stops the proliferation of micro-organisms that can cause food poisoning. European legislation requires food industry players to comply with regulation-prescribed temperatures during storage, transport and distribution. However, it does not impose anything on the last player in this chain: the consumer.
Transport: key link
This may seem obvious but it is during transport that you are the most at risk of breaking the cold chain. Its effectiveness relies not only on the temperature of refrigeration, but also on maintaining that temperature at a uniform level. There is nothing worse for food than having its temperature go up and down like a yo-yo! Of course, agribusiness and transportation professionals make every effort to ensure a constant temperature is maintained from the production centre to the shop shelves. But problems usually occur between the shop and the home, where it can be a few hours before food makes its way to the refrigerator or the freezer. Fortunately, once again, plastics come to consumers' rescue.
The cooler bag: a not-so-basic basic
They are now part of our daily lives. They just keep stacking up in many homes, and no one pays them any mind, and yet...Although they have become commonplace, cooler bags are a relatively recent invention, which will celebrate its thirtieth anniversary this year. Initially an American invention, it will yet take a few years to get a foothold in all channels of food product distribution. Although the concept is simple: to ensure the products contained in the bag are maintained at the same temperature for at least two hours is not quite as easy to manufacture. Three polymers are necessary to make a cooler bag: the outside is made from a metalised polyester that reflects sunlight, the central core is composed of a polyethylene foam and finally, the internal lining is a veil of white food-grade polyethylene. Admit it; this simple bag seems a lot more complex all of a sudden.
For the record, the bag's isothermal qualities mean that it also enables hot foods to be kept warm. It might not come as a surprise, then, that an American pizza chain was the first to seize the opportunity to use this invention.
Some bags even take a further step with the technology: they are enriched with a eutectic gel, usually a sodium methyl cellulose, sandwiched in the internal structure which, once chilled, doubles the duration of food preservation. It is particularly suitable for transporting highly sensitive goods such as meat and deli products, or dairy products made from raw milk, for instance. This particular bag concept has found use in the transport of drugs which absolutely need to be kept cold. So, thanks to these bags, vaccines can be delivered around the world without using refrigerated transport.
Ice boxes haven't been left out in the cold
One could be forgiven for thinking that these new bags would do away with the traditional ice box. Far from it! Ice boxes were able to evolve, too. They are no longer the bulky and heavy plastic boxes of old. Modern ice boxes are now light and flexible. Although the principle is substantially the same as that of isothermal bags, they are, in most cases, made of polystyrene, a very light and perfectly insulating material which provides the bow with some degree of rigidity. Its outer surface is lined with a polyamide-type synthetic fabric onto which is sewn handles and shoulder straps for ease of transportation. The latest models even come with a separate compartment for eutectic cooling blocks. This particular development isn't frivolous in the least because it is strongly advised not to put these blocks into contact with food in order to avoid the risk of freezing.
The plastics that keep
Food transportation no longer holds any mystery for you. You now know how not to go about breaking the cold chain. That's good, but it is unfortunately not enough to ensure your food is safe to eat. Once you get home and take your food out of its packaging, bacteria will gradually do the job...Luckily, this is a problem that can be solved. Ideally, you'll stem the proliferation of bacteria by isolating your food from natural light and air... Not an easy task! Natural light obviously won't enter into a refrigerator, but air will steel circulate freely. And a well-stocked fridge is the perfect place for bacteria to indulge in a multiplying frenzy. The best answer is to keep food vacuum-packed. Although they are not widely commercialised, there are machines available on the market which are able to aspirate the air between two layers of polypropylene plastic film. Effective but expensive! So, what to do?
Mister Tupper's genius
For many, Tupperware® is practically a noun. This plastic box would revolutionise the lives of innumerable "housewives", as they were known at the time. In 1946, Earl Tupper, a chemical engineer, developed a polyethylene box designed to improve food preservation. Three years later, he honed his invention right up to covering it with an air-tight lid. Tupperware® was born and the revolution began! It went on to be a phenomenal success in most developed countries. As always, good ideas are quickly copied. The company had to compete in a race towards continuous innovation in order to stay ahead. Over time, the boxes took on new colours, became larger, and longer...a box for each type of food...the marketing department strikes again, but we have to recognise that they form a particularly effective barrier to air. They are mostly manufactured mainly from polypropylene or low density polyethylene and always to the highest and most stringent standards.
Smarter packaging
The so-called modified atmosphere packaging that significantly extend the shelf life of "fragile" foods such as meat or salad have been around for a few years already. The technique is simple: the oxygen content of the air in the perfectly airtight packaging is reduced while its nitrogen and/or CO2 content is increased. This constitutes a first step in this direction and will certainly not be the last, since research is being actively pursued and it would seem that we, as consumers, won't have to wait very much longer before new, more intelligent packaging becomes more widespread.
The idea behind the packaging is to preserve product quality by maintaining or creating suitable conditions for their conservation. In order to achieve this, active systems are added to the packaging. These microcapsules are generally incorporated directly into the perfectly airtight centre of the packaging. They can prevent gases that damage the product from forming, or they can release preservatives or antioxidating agents. Active packaging is thus divided into two broad categories: absorbers which remove unwanted elements (e.g. oxygen or odour absorbers, or moisture regulators), and release-systems that introduce beneficial elements to the product-packaging whole, e.g. antimicrobial agents, whose role is to slow down the growth of microorganisms.
