Drying, chilling, freezing, sterilisation and pasteurisation describe just some methods of food preservation. However, all of these have major drawbacks — including the loss of essential nutrients and flavour. Here, Charlie Ahern, general manager at aluminum packaging supplier Advanta, explains.
In 1877, French scientists Pasteur and Joubert observed that Bacillus anthracis, a common type of bacteria, could be killed using carbon dioxide (CO2). From here, the preservative method of CO2 took off commercially.
However, it wasn’t CO2 that was deadly to the bacteria, but rather the lack of oxygen. Today, there are three main types of packaging techniques that take advantage of low oxygen levels; modified atmosphere packaging (MAP), controlled atmosphere packaging (CAP) and vacuum packaging.
Let’s kick things off with MAP. This describes the modification of the air inside the package, displacing normal air for a composition of gases that is low in oxygen. This normally means more nitrogen or carbon dioxide is included than normal. Of course, the composition depends entirely on the type of food, and the permeability of the film.
For respiring products, such as fresh fruit and vegetables, the aim is to minimise its respiration rate. For non-respiring products, such as cooked poultry or fresh pasta, it’s all about minimising microbial growth as the main spoilage parameter.
Getting the composition right can result in highly extended shelf lives for MAP packed products. Fresh poultry, for example, normally has a shelf life of three to ten days, but can withstand six to 21 days with MAP.
Using MAP, you cannot control what happens after the produce is packaged and respiration continues. However, with CAP, you can make alterations to the storage conditions of the packaging during its lifespan. This involves adding oxygen absorbers or nitrogen to achieve the optimal gas composition to extend shelf life. The temperature and humidity of the product’s storage atmosphere is also regulated to reduce spoilage.
CAP is a storage technique, rather than a shelf-ready retail tactic. However, it does make a huge different to food logistics, ensuring ingredients arrive and are stored, in the best conditions possible. Just like MAP, this increases shelf life, reducing food waste and resulting in better convenience for the customer.
Vacuum packaging does what it says on the tin, it is created by sucking the air out of packaging. However, not all oxygen is removed in this process.
The removal of most of the oxygen impedes the ability of oxygen-breathing microorganisms, meaning they cannot grow and spoil the product. The lack of oxygen also reduces the amount of spoilage due to oxidation – the same process that causes apples and bananas to turn brown.
Unlike traditional methods of preserving food, these methods allow the preservation of food products without the addition of any chemical preservative and stabilisers. Whichever technique you choose for your products, these methods all support the conservation of nutrients and other functional properties.
Ultimately, that’s what today’s health conscious consumer is looking for.