Fresh red meat products were conventionally packed in Styrofoam trays with PVC stretch films. The stretch film is highly permeable to oxygen and allows the freshly cut meat to bloom. The shelf life is limited to 2 – 4 days in the refrigerator due to microbiological growth. The gas composition in the headspace is near ideal for the growth of spoilage organisms (predominantly Pseudomonas varieties). Their growth becomes apparent as off-odours, slime formation and discoloration.

In Modified Atmosphere Packaging, the meat is packed in a protective gas mixture within a gas barrier package. The most widely used gas mixture is 60 % O₂, 30 % CO₂ and 10 % N₂. The elevated oxygen level stabilises the red meat colour. The elevated carbon dioxide level retards the growth of micro-organisms, especially Pseudomonas, resulting in a prolonged shelf life of 5-8 days. Various companies sell a variety of MAP-machines:

• Tray sealers, in which the meat is placed in pre-formed barrier foam trays, vacuumed, flushed with the desired gas mixture and sealed with a transparent barrier top film.
• Thermoformers, in which trays are freshly thermoformed, the meat is placed in the trays, vacuumed, flushed with the desired gas mixture and sealed with a transparent barrier top film.
• BDF, (Barrier Display Film packaging) in which the meat is placed in a standard Styrofoam tray, vacuumed and then flushed with the desired gas mixture. The tray is completely enclosed in a gas barrier film that is heat shrunken around the tray.

All these MA-packaging techniques have their pros and cons. Tray sealers produce an attractive top-sealed package that resembles a conventional Styrofoam package but which require a voluminous warehouse to store trays of all the required formats. Thermoform machines require operators to have good technical control over forming and sealing the trays. The trays can be completely transparent or look similar to foam trays. BDF is a relatively cheap and out-dated technique that suffers from a high failure rate and a less appealing image.

Improving on MA-packaging technology is ongoing. In Norway, MA-packages with 30 % CO₂, 0.5 % CO and the balance N₂ have been successful in obtaining an even longer shelf life. However, the implementation of this technique in the EU, Canada and the USA is restrained by legislation that forbids the use of carbon monoxide.

Some American meat processing companies have invested heavily in Master Pack technology. About a dozen highly oxygen permeable consumer-packages are packed in Master cartons with a 100% carbon dioxide atmosphere. The pure carbon dioxide gas greatly prolongs the shelf life (up to 3-4 weeks). A long shelf life is required for the long distribution distances in North America. The Master cartons are opened at the supermarkets and the meat starts to bloom, with a remaining shelf life of about 2-4 days. Although much research has been conducted and large investments have been made, the Master Pack technology is not being used in Europe, is used only to some extent in Australia and New Zealand and hardly being used in the USA or Canada for various reasons:

• Investments at the centralised meat packing company are relatively large,
• Legislation requires the packaging date to be printed on the packages, warning the consumers they are buying ’old meat’,
• Health hazards are large at two critical control points (packaging integrity and initial meat quality) and a strict control is necessary.

As a result, MAP-technology is still the leading technology for packaging fresh meat in Europe.

The prolonged shelf life of the fresh meat products can be used beneficially in many ways. When these benefits are taken in the right manner, the additional costs of the MAP-system are more than paid back by cost savings elsewhere in the supply chain. A good business plan that takes the complete supply chain into account helps to switch over successfully. Typical benefits associated with MA-packages are listed in the table below:

Fluctuations in the demand for meat products have always troubled the supply chain. The longer shelf life helps buffer these fluctuations. This helps to relax the production and distribution. Moreover, it helps to reduce the retail losses due to unsold products and lost sales from out-of-stock situations. A detailed information exchange system on stock levels and sales between producers, distributors and retailers can greatly assist the success of all retail meat businesses and especially for MAP-technology.

The introduction of MAP-technology also has a downside. The volume of product flow is increased because the size of the MAP package is larger. This is most noticeable with large meat products such as roasts and rolled meat. The number of packages per crate /case is greatly reduced. Hence, the volume of the warehouses, the number of trucks and the display space in the supermarket might require expansion.

Past misconceptions that MAP-technology would improve the quality of poor quality meat or reduce the level of control required of the chilled supply chain have proven false. Hard lessons were learned that MAP-technology can only extend the shelf life with good quality meat and in a supply chain with a good temperature control.

Partners in research

We can help to make switchovers to MAP successful. It has been involved in various meat supply chain and packaging research projects and has experience in meat quality, packaging technology and logistical optimisation. We have collaborated with the Food Process Development Centre (FPDC) of Canada on meat projects. ID-Lelystad, is the cattle and meat quality research institute in The Netherlands. It performs all controls of cattle disease and meat quality and microbiological checks for the Dutch Ministry of Agriculture. The FPDC in Canada is a highly experienced research centre with expertise in meat quality and meat processing. It is also involved with switchover projects in Canada and possesses much knowledge of the North American meat market and legislation.