Modified Atmosphere Packaging of Dairy Products

Extending the shelf-life of dairy products

MAP modified atmosphere packaging for dairy products, including Aerosol creams, blue and white mould-ripened cheeses, butter, cream cakes, creams, custards, fresh cheeses, grated cheeses, hard cheeses, margarine, semi-hard cheeses, sliced cheeses, soft cheeses and yoghurts.

The principal spoilage mechanisms affecting dairy products are microbial growth and oxidative rancidity. The type of spoilage affecting dairy products will depend on the intrinsic properties of the different products. For example, low water activity products such as hard cheeses are generally spoilt by mould growth, whereas higher water activity products such as creams and soft cheeses are susceptible to yeast and bacterial spoilage, oxidative rancidity, and physical separation.

MAP can significantly extend the shelf-lives of dairy products. Similar shelf-lives are achieved for MAP as opposed to vacuum packaging. Hard cheeses are generally packed in CO2 gas which is very effective at inhibiting mould growth. Soft cheeses are packed in CO2/N2 gas mixtures, which can also inhibit bacterial spoilage and oxidative rancidity. For soft or grated cheese, 30% CO2, 70% N2 is recommended. MAP modified atmosphere packaging is particularly effective for crumbly cheeses such as Lancashire and grated cheese where vacuum packaging would cause undesirable compression.

MAP is not recommended for mould-ripened cheeses since CO2/N2 gas mixtures would kill desirable mould growth, causing it to turn an unpleasant yellow. Creams are adversely affected by CO2-containing atmospheres which cause acidification of the cream, giving it a sharp rather than smooth taste. Consequently, N2 is recommended for MAP of creams and cream containing products. A gas/product ratio of 2:1 is recommended. By exclusion of air, N2 is also capable of inhibiting aerobic microbial growth and oxidative rancidity. Aerosol creams use nitrous oxide (N2O) as a propellant, which also inhibits oxidative rancidity.

Other dairy products such as butter and yoghurt are not usually MAP packed but would benefit from packaging under N2. Possible food poisoning hazards associated with dairy products are primarily due to either inadequate pasteurisation or cross-contamination during or after packaging. Consequently, adequate pasteurisation, the maintenance of recommended chill temperatures, and good hygiene and handling throughout are essential for ensuring the safety of dairy products.

General Information for Modified Atmosphere Packaging of Dairy Products