How to nitrogen flush coffee bags

Jane Merchant
April 14, 2022
nitrogen flush coffee

For specialty coffee roasters, preserving freshness is vital to maintaining the distinct flavours and aromas of their coffee before it reaches the consumer.

Factors such as oxygen, light, and moisture can cause coffee to lose freshness immediately after it is roasted. Thankfully, there are a number of options available to roasters to prevent exposure to these factors.

One of the most popular methods is for roasters to flush their coffee packaging with nitrogen, also referred to as nitrogen flushing.

This is a technique that replaces the oxygen in coffee packaging with nitrogen, creating a cushion of gas that protects the coffee during transport and storage.

Read on to find out more about nitrogen flushing and why roasters use it for their packaged coffee.

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flushing coffee with nitrogen

What is nitrogen flushing and how does it work?

Nitrogen flushing is a form of Modified Atmosphere Packaging (MAP), which was first adopted by retailers in the 1970s.

The process involves packaging food in an atmosphere containing carbon dioxide (CO2), nitrogen, or oxygen in certain quantities in order to create a specific profile.

Initially, MAP was developed for perishable food items that continue to emit CO2 and water vapour, while taking in oxygen after it has been packaged. This includes meats, vegetables, fruits, and coffee, for example.

Gas packing, also known as flushing, is another form of MAP. This method involves injecting a continuous stream of gas into a packaged product until it has replaced all the air. This displaces most of the oxygen and CO2, replacing it with nitrogen. Nitrogen is an inert gas, which means it doesn’t react with the product.

This process can help extend the shelf life of coffee and prevent staling. The process of staling is accelerated by a buildup of CO2, as well as exposure to moisture, heat, oxygen, and light.

These elements even impact vacuum packed, low oxygen coffee, with oxidation increasing according to packing density and grind size.

Notably, research shows nitrogen flushing may double the shelf life of packaged coffee in certain circumstances. It may be even more effective when combined with vacuum sealing and layered packaging that contains degassing mechanisms.

recyclable coffee bags

Nitrogen flushing your coffee bags

With MAP nitrogen flushing, the proportions of gases used can lead to different outcomes and packaging choices.

For instance, red meats benefit from nitrogen flushing as it removes excess oxygen. However, removing too much oxygen can leach the meat’s characteristic red colour.

A number of mouldy cheeses require some oxygen to preserve existing mould growth, but not too much that it becomes too ripe. This is why packagers tend to flush it with CO2 and use semi-permeable packaging to preserve its condition.

When it comes to coffee, nitrogen flushing is highly effective in keeping packaged roasted coffee free from CO2 and moisture. Additionally, it does not require semi-permeable packaging, making it suitable for most forms of coffee packaging materials.

Furthermore, nitrogen is naturally and abundantly available in the atmosphere, making it affordable and accessible.

The process of nitrogen flushing involves filling each bag with grounds or beans and feeding the filled bags into a dispenser that flushes and seals the bag at once.

Including a degassing valve will help the coffee continue to degas without the risk of the bag exploding. As the flushing process equalises the pressure inside and outside the bag, the valve’s seal encounters less resistance, making it more effective.

It is estimated that nitrogen flushing leaves a bag of coffee with less than 3% of its original oxygen levels, which may be why many roasters use it as part of their packaging process.

For example, Georgia-based Volcano Coffee uses nitrogen flushing as they roast to order. This process allows them to package their coffee on the same day it’s roasted, and get it to customers within two weeks.

Volcano adds that vacuum sealing can take up to 72 hours, as they first need to allow the coffee to degas as much as possible.

nitrogen flushed coffee bags

Selling nitrogen flushed coffee 

For roasters who are considering using nitrogen flushing in their packaging process, there are a few things they need to consider.

First is the volume of orders, turnaround time, and roast capacity. According to Australia’s Seven Miles Coffee, nitrogen flushed coffee is best two weeks after roasting. Additionally, they claim flushed coffee can remain fresh for up to eight weeks after that.

They believe that coffee packaged without nitrogen flushing tastes best roughly one to three weeks after roasting. This means roasters will want to reserve nitrogen flushing for packaging larger orders or for those travelling longer distances.

Another key point is roasters need to test packaging after flushing. This is essential as an increase of just 2% of oxygen can render the nitrogen flushing process pointless and will not preserve the coffee.

While nitrogen flushing is an excellent preservation tool for primary coffee packaging, coffee will have a secondary shelf life that begins once the packaging has been opened.

Investing in packaging with strong barrier qualities and resealing mechanisms will help preserve the coffee so consumers can enjoy its unique flavour profile.

Essentially, roasters must package and brand their coffee in a way that not only attracts customers, but protects it during transit and extends its shelf life for as long as possible.

At MTPak Coffee, we have a range of multilayer coffee bags that will keep out oxygen, while providing full sustainability. We offer a choice of natural, 100% compostable and recyclable packaging options, such as kraft paper and rice paper.

Additional choices include PLA and LDPE coffee bags, and all of our packaging options are fully customised using sustainable materials such as water-based inks. We also offer recyclable degassing valves that can be fitted to the bags either before or after manufacture.

Furthermore, we can help you decide on the best resealing option for your coffee bags, from pocket and loop zippers, to tear notches and zip locks. All our resealable features can be integrated into our recyclable, compostable, and biodegradable coffee bags.

If you are a micro roaster, we offer low minimum order quantities (MOQs) on a number of packaging options.

For more information about our sustainable coffee packaging, contact the team

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