Food Packaging - It's A Gas!

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Having recently opened a supermarket bag of salad one week after the 'use by' date I was shocked to find that it was... absolutely lovely! Of the six different types of leaves, none of them had gone brown or started to liquefy! One of my office colleagues then told me that they had eaten bagels from an unopened packet some two weeks past the 'use by' date and had clearly lived to tell the tale.
Leaving aside the confusion caused by nuances in the labelling with terms like 'best before', 'use before', 'use by' and and 'sell by', it is clear that some foods have taken on a magical property that makes them last longer than they would 20 years ago. Actually it is the packaging that has changed and specifically making the package air tight and adding a protective gas – it is the gas that then enables the contents to stay fresh for as long as they do.

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Food Packaging - It's A Gas!
Image is licensed under CC Attribution

The first industry to embrace the idea of using gas was the soft drinks industry. Towards the end of the 19th century people were commonly adding Carbon Dioxide to drinks either by using soda fountains or with bottling. The beauty with doing this was that it not only improved the taste of the water or flavoured drink, but it also kept it preserved. Nowadays processes are much more sophisticated with different gases being used depending on the products – so in the example of the salad packaging, the packaging company will generally create a 90% Nitrogen atmosphere within the bag. If there was normal air in the bag, the oxygen in it would speed up oxidation - the process of decay.
Food Packaging With Gas
License: Image author owned
One of the main things that causes food to go off is the growth of microbes such as mould, bacteria and yeasts and these are naturally present in the air. Fresh air will also change the colour and appearance of food over time, and even if this is not harmful it will lessen the attractiveness of the food making it more difficult to sell. In the case of raw meat, there is an optimum mix of Oxygen (70%) and Nitrogen (30%) which will help preserve the colour of the meat. According to the website Modified Atmosphere Packaging website there are a number of recommended packaging gas mixtures for retailers, some of which are listed below:
  • Raw poultry and game - Carbon Dioxide (30%), Nitrogen (70%)
  • Oily fish and seafood - Carbon Dioxide (70%), Nitrogen (30%)
  • Low fat, white fish - Carbon Dioxide (40%), Nitrogen (30%), Oxygen (30%)
  • Cured, cooked and processed meat - Carbon Dioxide (30%), Nitrogen (70%)
  • Ready meals – Carbon Dioxide (50%), Nitrogen (50%)
  • Fresh Pasta products - Carbon Dioxide (50%), Nitrogen (50%)
  • Bakery products - Carbon Dioxide (50%), Nitrogen (50%)
  • Hard Cheeses - Carbon Dioxide (100%)
  • Soft Cheeses - Carbon Dioxide (30%), Nitrogen (70%)
  • Fruit juices - Nitrogen (100%)
It is probably a little unfair to blame the food industry for modifying the air content in food packaging as after all it is us, the consumer, who wants attractive-looking food which will last a long time. I'm sure the representatives of the food industry would no doubt point out that this practice is actually much better for us than putting additives in food. There is also the positive benefit in allowing retailers and consumers to use slightly less refrigeration in the transport and storage of the food. Food companies have invested considerable research in producing the optimum gas mixture technologies and in manufacturing packaging that doesn't leak.

It would of course be preferable if everyone bought fresh fruit and vegetables from their local market or corner shop, and bought all their meat from a butchers and bread from a bakery. It would also help if we were all slightly less obsessed with everything looking beautiful. But let's face it, this isn't going to happen so the result is that we will have to accept that much of the 'fresh' food that we buy is now gassed!

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Richard
About the Author:

Richard Bloomfield is the website editor for the Workplace Depot – a supplier of equipment to leading retailers and food manufacturers

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