Dairy Products

Food items: 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, Yoghurts, other items

Recommended gas mix

Hard cheeses except mould-ripened cheeses
100% CO₂

Grated and soft cheeses
except mould-ripened cheeses
30% CO₂ 
70% N₂

Other dairy products
100% N₂

Exceptions:
Aerosol creams: Nitrous oxide (N₂O)

The gases and mixtures listed above are for general guidance. To identify the optimum gas for your product and process, we recommend you undertake a product trial, with the help of an Air Products MAP gas specialist.

Storage temperature
Legal maximum*: 8° C
Recommended: 0° C to + 5° C

Achievable shelf-life
In air: 1-4 weeks 
In MAP: 2-12 weeks

Principle spoilage organisms and mechanics
Pseudomonas species (in air), Brochothrix species, Lactic acid bacteria, Entereobacteriaceae, yeasts and moulds, oxidative rancidity, physical separation.

Food poisoning hazards include
Clostridium species, Salmonella species, Staphylococcus aureus, Listeria monocytogenes, Bacillus species, E.coli and E.coli 0157.

Typical MAP machines
Retail
• TFFS – Thermoform-fill-seal
• PTLF – Preformed tray and lidding film 
• HFFS – Horizontal form-fill-seal
• VFFS – Vertical form-fill-seal 

Typical types of package** 
Retail: Tray and lidding film, Tray inside pillow pack, pillow pack 

Examples of typical MAP materials
Retail
Tray: 
• UPVC/PE
• HDPE 
• EPS/EVOH/PE

Lidding and/or pillow pack film:
• PET/PVdC/PE
• PA/PVdC/PE
• PC/EVOH/EVA
• MPET
• MOPP
• OPP/PVdC

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 aw products such as hard cheeses are generally spoilt by mould growth, whereas higher aw 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 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 MA 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.

* The Food Safety (Temperature Control) regulations 1995 states that the maximum Storage temperature for chilled perishable foods is 8°C. There will be flexibility to vary this when scientifically justified. For legal temperature storage requirements, please contact the Campden and Chorleywood Food Research Association.

** Tubs and pots are commonly used for yoghurts, soft cheeses, margerine, creams, custards and butter.