Milk Powder Packing with Nitrogen

Milk powder is much more stable than fresh milk but protection from moisture, oxygen, light and heat is needed in order to maintain it's quality and shelf life. Milk powder readily takes up moisture from the air, leading to a rapid loss of quality and caking or lumping. The fat in whole milk powder (WMP) can react with oxygen in the air to give off-flavour, especially at higher storage temperatures (> 30°C) typical of the tropics.

Whole milk powder contains between 25 and 40% fat, it is highly susceptible to oxidation and therefore off-flavours, even rancidity.

The standard for shelf-life of milk powder is 6 to 9 months if stored below 27°C and 65% relative humidity, although flavour changes may occur as early as three months if kept at ambient temperature. It is obviously important to both producers and end users that storage stability should be as long as possible.

Research was done to study the effects of milk powder packaging atmosphere, storage temperature and storage time on milk powder shelf-life. For the packaging atmosphere - air was compared to nitrogen flushing, for storage temperature 2°C was compared to 23°C, and changes were monitored over a total period of one year. It was found that Nitrogen-flushing when whole milk powder is packed and storing the packaged product in the fridge extends shelf-life considerably and should prevent off-flavours.

Research shows that optimum shelf-life of milk powder in terms of flavour (loss of "fresh" flavours and/or development of "grassy" off-flavour) was about 3-months, regardless of package atmosphere or storage temperature. After six months, "painty" off-flavours in milk powder were detected by the sensory panel in chocolate. Nitrogen flushing greatly enhanced storage stability of milk powder by preventing the development of "painty" flavour. It was concluded that packaging oxygen levels should be as low as possible to prevent rapid oxidation and off-flavours. Cooler (2°C) storage temperature also enhanced storage stability of milk powder, but to a lesser extent than nitrogen flushing. It was also shown that milk powder stored in nitrogen-flushed packaging for up to one year could be successfully used to manufacture milk chocolate.

It is now clearly understood in the dairy industry, packing of whole milk powders and other products with Nitrogen, extends the shelf life and prevents spoilage due to oxidation. Nitrogen is an efficient, cost-effective way to displace oxygen and moisture.

Nitrogen gas is a critical element in the milk packing industry. Nitrogen Gas is available in cylinders (which is very costly) and it can also be produced on site.

MVS Engineering offered a wide variety of On-Site Gas Generators (such as one pictured above) for producing Nitrogen in the manufacturer's own factory.

Producing gases on-site has following advantages:
  • Much lower cost than purchasing Nitrogen from outside
  • Investment pay-back in as little as 1-year
  • No dependence on external gas supplies
  • Control over quality of Nitrogen
  • No hassles of handling/transportation of cylinders
  • Nitrogen is available round-the-clock
  • Very simple unit, requiring no attendant - fully automatic system

Read more about our Nitrogen gas generators.