Nitrogen keeps packaged food fresh by pushing oxygen out of the pack. With little oxygen left, fats do not turn rancid, colour and flavour hold, and aerobic bacteria and moulds cannot grow. Food-grade nitrogen (E941) must be at least 99% nitrogen with no more than 1% oxygen, and many packers run 99.5–99.9% to reach a lower residual oxygen in the pack. An on-site PSA nitrogen generator makes this nitrogen from air at a fraction of the cost of cylinders or liquid nitrogen.
This guide covers how nitrogen packaging works, what purity to specify, which foods benefit, and how to size a generator.
How nitrogen packaging works
Oxygen is the main cause of spoilage in packaged food. It drives oxidation, which turns oils and fats rancid, fades colour and dulls flavour, and it feeds aerobic bacteria, yeasts and moulds. Nitrogen is inert: it does not react with food and is about 78% of the air we breathe.
Three common methods use it:
- Nitrogen flushing: nitrogen is blown into the pack just before sealing, pushing out the air. Used for chips, namkeens, nuts, coffee and powders.
- Modified atmosphere packaging (MAP): the air in the pack is replaced with a controlled gas mix, usually nitrogen, sometimes with carbon dioxide. Residual oxygen is typically brought down to the 1–5% range or lower, depending on the product.
- Blanketing: a layer of nitrogen over tanks of edible oil, juices or wine keeps oxygen away during storage.
What nitrogen purity do you need?
Purity is the share of nitrogen in the gas. The rest is mostly oxygen, so purity decides how much oxygen ends up in the pack.
Food-grade nitrogen (E941) is commonly specified as:
| Parameter | Limit |
|---|---|
| Nitrogen | At least 99% |
| Oxygen | No more than 1% |
| Carbon monoxide | No more than 10 ppm |
| Carbon dioxide | No more than 300 ppm |
| Moisture | Very low (dry gas) |
For most snacks and dry foods, 99.5–99.9% nitrogen is enough. Higher purity costs more to make, because a PSA generator needs much more compressed air for every extra “9”. Specify what the product needs, not the highest number. For the standard in detail, read food-grade nitrogen and EIGA Doc 941.
Which foods benefit
| Food | Why nitrogen helps |
|---|---|
| Chips, namkeens, fried snacks | Stops oils turning rancid; keeps crispness; cushions the pack. See nitrogen purity for fried snacks |
| Nuts, dry fruits and coffee | Prevents oxidation of oils and loss of aroma |
| Grains and pulses | Protects stored grain from insects and oxidation. See nitrogen in grain and pulse packaging |
| Dairy (cheese, milk powder) | Prevents off-flavours and mould |
| Meat, poultry and seafood | Slows spoilage and discolouration in MAP |
| Fresh-cut fruit and vegetables | Slows browning and microbial growth |
| Edible oils, juices, wine and beer | Blanketing in tanks; dispensing and dosing in beverages |
Benefits of an on-site PSA nitrogen generator
- Lower cost per Nm³ than cylinders or liquid nitrogen, with no rental or delivery charges.
- No running out: nitrogen is produced on demand, 24×7, so lines do not stop waiting for cylinders.
- Purity control: set the purity each line needs, and an analyser confirms it continuously.
- Food-safe air treatment: filters and dryers remove oil, moisture and particles before the gas reaches the product.
- Less waste: longer shelf life means fewer returns and less spoiled stock.
How to size a nitrogen generator for packaging
- List each machine and its nitrogen use in Nm³/hr. Machine makers usually state this.
- Map when they run, shift by shift, to find the average and the peak.
- Set the purity and pressure the machines need. Packaging machines often need only 2–3 barg.
- Use a storage tank to cover peaks, so the generator can be sized nearer the average.
See how this worked for a food packager with 50 machines: right-sizing with a 20 KL tank cut their plant from 160 to 120 Nm³/hr and saved about ₹51 lakh a year. Read how to size a nitrogen plant for varying demand.
For payback against cylinders or liquid nitrogen, use the free ROI calculator.
Talk to us about your packaging line
See nitrogen generators for food and beverage, or the compact nGENX, popular for food packaging. Email info@absstem.com or call 1800 547 0506.