MechChem Africa

Today’s consumer is more aware and discerning when it comes to buying fresh foods. Afrox’s Hendrik Pretorius highlights safety trends and the advantages of involving a food gas expert when preparing perishables for sale to the modern consumer.

Increasingly, the modern consumer is driving packaging OEMs towards change with respect to extending the shelf life of fresh food, and its quality and appearance on supermarket shelves, says Afrox gas mixtures specialist, Hendrik Pretorius.

Afrox food safety MAP Flash Freezing Consumers want to be able to purchase and prepare fresh produce at any time, as if it came directly from the farm. What they forget, however, is that to get fresh food to the supermarket, it often has to be transported hundreds of kilometres from a farm, food factory or depot, Pretorius points out.

“Keeping products fresh, and meeting the growing consumer demand for healthy, minimally processed and attractively packaged foods, is changing the technologies used by food processors, the food transport industry and supermarkets worldwide,” he says.

“And those reluctant to embrace these new technologies are increasingly likely to be punished by rigorous public health and safety legislation and, more significantly, deserted by consumers.”

Pillow packaging of fresh ready-to-eat vegetables and other food products, for example, is extending shelf life without the need for freezing or any other preservation technology.

Instead, the product is sealed in a puffed-up plastic bag filled with a purpose-developed gas mix that protects the food from natural spoilage caused by moisture, oxygen, bacteria or other contaminants in the atmosphere.

This is where Modified Atmospheric Packaging (MAP) comes in. It involves the use of different gas mixtures to extend shelf life – typically by up to a week for fresh produce – and to retain the fresh look of the product.

The key to this technology lies in varying the concentration of the different gas mixtures used, explains Pretorius. Typically, carbon dioxide (CO2), nitrogen (N2) and oxygen (O2) are used in a scientifically developed mix to provide the life-extending needs of the product being packaged.

“While the use of quality products, temperature control and hygienic conditions are vital to the process, the use of the right gas mixtures and packaging are central to the optimisation of shelf life,” says Pretorius.

For most foodstuffs, the package should contain as little oxygen as possible – typically less than 1 to 2% – to retard the growth of aerobic microorganisms and reduce the degree of oxidation. However, there are exceptions. Oxygen helps to preserve the oxygenated form of myoglobin, which gives fresh meat its red colour, for example.

Carbon dioxide, according to Pretorius, is the most important gas in the field of MAP technology. Most microorganisms, such as mould and common aerobic bacteria, are strongly affected by carbon dioxide.

Citing a recent experience of a meat product manufacturer, Pretorius says: “The manufacturer had launched a new sausage in its current range by adding organic constituents, such as onion and herbs to the meat mix.

“However, this changed the dynamics of the reaction with the MAP gas and after a week and a half, an acidic ‘white water’ was seen coming off the product. Not exactly an enticing sight for any consumer.

Fortunately, Afrox was able to quickly identify the problem and provide a rapid solution. It did take specialist gases knowledge in order to do so, but that specialist knowledge also added real value to the production process of this new product.

While MAP saves money and improves the quality of the food, of far greater importance is that food safety is improved and consumer confidence in the food industry, up and downstream, is protected.

Pretorius advises that instead of employing full time MAP and gas specialists, food processors and packaging companies should rely on the extensive experience and know-how of a gases company such as Afrox to provide the right solutions.

“As an added benefit, fresh food manufacturers and producers also have access to the latest in gases technologies emerging out of extensive research by The Linde Group, Afrox’s global parent company,” says Pretorius.

Liquid nitrogen and cold chain

By volume, dry air contains over 78% nitrogen and nearly 21% oxygen. So in any cryogenic air separation unit (ASU), the largest liquefied gas being produced is nitrogen.

Nitrogen has no taste, colour or odour and it is non-toxic. We breathe it in and out all the time, without any negative effects. It is also mostly inert, making it ideal for use to exclude moisture and oxygen from the likes of pillow packaging for products such as potato crisps.

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