How Nitrogen Extends Food Shelf Life

Sep 15, 2021

Table of contents

packaged crackers on shelf

While oxygen has no shortage of positive effects on our bodies, it can be detrimental to the life of food products. Once it comes in contact with the organic matter we eat, oxygen causes quick deterioration, from turning fats rancid to fostering the growth of undesirable bacteria. To meet consumer demand for longer-lasting products and maximize the value of food, nitrogen and modified atmosphere packaging (MAP) have emerged as important players.

Keep reading to learn about MAP and why nitrogen gas is used to preserve food.

In This Article

What Is Modified Atmosphere Packaging?

MAP is a type of packaging that creates an extremely low concentration of oxygen in the atmosphere surrounding the product inside the packaging. Needs will vary by product, but you can often expect a concentration of 1-5% oxygen in the immediate atmosphere around the item. This concentration creates a buffer, protecting the item from the adverse effects of oxidization and physical damage from jostling within the package.

MAP can occur through various methods, but it usually involves either a gas-flushing process or special films. These two processes represent the two types of MAP, active and passive:

  • Active MAP: Active MAP is used when displacing oxygen by pumping the packaging with a gas with a low oxygen concentration. The most common choice here is food-grade nitrogen, which is inexpensive and can easily be generated to purities higher than 99%. Active MAP is used with products that don't respire much, like meat and fish. Active MAP works with bags, cans and drinks, too.
  • Passive MAP: Passive MAP relies on the natural respiration of the product and how the chemistry of those gasses diffuses through special films used in the packaging. Some fruits and vegetables, for example, do a lot of respiring and must be able to transmit gas through a permeable film. These products may need passive MAP techniques to suit the needs of the food.

Products will react to MAP in different ways, and its effect can extend freshness anywhere from a few days to a few years, depending on the item. Seafood, for instance, is on the lower end of the spectrum and might see a little less than a week of extra freshness, while cheese and bread can be kept fresh for several months with the help of MAP.

All of this is done to keep the spoiling effects of oxygen at bay — it's one of the quickest routes to spoilage for most perishable items. Some of its impacts on these products include microbial growth and oxidized fats. Oxidization can also affect the taste and color of a food item.

Gas Flushing With Nitrogen

One of the most common solutions to displacing oxygen in food product packaging is to replace it with nitrogen. How does nitrogen keep food fresh? Nitrogen is dry and inert and can minimize the growth of aerobic organisms, making it an excellent candidate for the job. It's also useful for filling up the package to maintain conformity. Additionally, it's completely safe — it makes up about 78% of the air we breathe every day.

how does nitrogen keep food fresh

The process of gas flushing works because nitrogen is heavier than oxygen. Nitrogen gas flushing can be done in flexible packaging, cans, bags and other types of containers. When selecting packaging, manufacturers must consider several aspects, such as gas permeability, water vapor transmission rate and sealing reliability, which will determine how effective MAP can be.

It's possible to purchase the nitrogen itself from third-party vendors, but the nitrogen is often generated on-site with a nitrogen generator, which may not be your best bet. Many food and beverage manufacturers and processes like to use gas generators because they're cost-effective with minimal maintenance requirements, and they offer on-demand gas according to production requirements. There's no need to wait for a shipment from a third-party provider or pay extra for expedited service.

The vacuum packaging equipment takes it from there and uses your nitrogen supply to displace the oxygen and provide a valuable nitrogen barrier around the product. It'll quickly seal up the container to keep the nitrogen in place and send it along to shipping.

How Nitrogen Protects Food

What exactly does this additional barrier of nitrogen do for a food product? It all comes down to reduced exposure to oxygen, which prevents:
  • Discoloration: Consumers expect a particular color when buying food. Even though oxygen doesn't spoil the food, it can still be discolored, creating a less-appetizing product and experience for the customer. This process is called enzymatic browning and often occurs in fruits and vegetables as the enzymes' natural processes are sped up in the presence of oxygen. If you've ever cut an apple and watched it turn brown when you don't eat it quickly, you've seen enzymatic browning in action. This type of oxidation can also cause the nutritional content of a product to be reduced.
  • Spoilage: Of course, as food is exposed to the elements, it's going to break down faster. Exposure to oxygen causes lipid oxidation, which brings discoloration and odd flavors, along with a loss of nutrients.
  • Texture differences: Oxygen spoilage can also affect the texture of the food, leading to mushy vegetables, stale chips and other effects.
  • "Off" flavors: Similarly, as food breaks down upon exposure to oxygen and as bacteria eats away at it, you might notice some odd flavors.

Many of these factors come from a combination of factors, like enzymatic processes, physical damage and microbial growth. That last factor can have various effects and isn't always visible — a perfectly ripe-looking tomato can be filled with undesirable bacteria. Different types of food are susceptible to many types of microorganisms, but keeping oxygen out of the equation is an effective way to prevent their growth and negative effects. 

Working With Reliable Nitrogen Equipment

Food spoilage is a considerable problem for consumers and society as a whole. Pennsylvania State University estimates that more than two-thirds of households waste between 20% and 50% of their food. In addition to making food and beverages more appealing to consumers, MAP with nitrogen can have a significant advantage in the fight against food waste.

If MAP sounds like an appropriate packaging approach for your product, the trustworthy equipment from Fluid-Aire Dynamics can make it possible. Our high-quality gas production devices include membrane nitrogen generators and pressure swing adsorption nitrogen generators. Both can help you achieve reliable, on-demand nitrogen generation to support your food preservation efforts. All of our equipment is backed up by our skilled team and exceptional product support.

We offer sales and services nationwide with locations in Illinois, Wisconsin, Minnesota, Texas, Michigan and Pennsylvania.

To learn more about our nitrogen generators and MAP processes, reach out to us today.

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