As soon as coffee is roasted, the steady decline of freshness begins almost immediately. Over the following days and weeks, internal changes in the coffee continue to take place as carbon dioxide (CO2) is released and a number of chemical reactions initiated during roasting cause the coffee to break down and become stale.
For specialty coffee roasters, it’s important to ensure that the freshness of their coffee is preserved right up until the moment of consumption. This means keeping it protected from light, oxygen, moisture, and heat, all of which can adversely affect the quality, flavour, and aroma of the beans.
Nitrogen flushing and vacuum sealing are two of the most effective ways of preserving roasted coffee. Both packing methods greatly reduce oxidation and slow the rate of staling, helping to keep coffee fresh for weeks, if not months, on end.
But is one better than the other? Read on to find out about the pros and cons of each method for specialty coffee roasters.
What Is Nitrogen Flushing?
For decades, nitrogen has played an important role in the preservation of food and beverages. Cheap to produce and relatively unreactive, it is a popular gas used by manufacturers looking to extend the shelf life of goods.
Nitrogen flushing is a technique for preserving and protecting perishable goods. It involves “flushing” the oxygen from packaging containers using nitrogen gas. Unlike oxygen, nitrogen doesn’t react with foods, nor does it affect flavour or texture However, it is heavier than oxygen and provides a “cushion” for the contents of the packaging during transportation and storage. It’s safe to inhale too; in fact, around 70% of the air we breathe everyday is made up of nitrogen.
One of the most common examples of nitrogen flushing is in bags of potato chips. Due to their delicate composition, the packaging must protect them from bumps and jolts typical of transit, yet also prevent them from becoming stale before they reach the consumer.
To nitrogen flush coffee, the beans (or grounds) are added to an open pouch before a machine is used to force the regular, oxygen-rich air out and replace it with nitrogen gas. To prevent the nitrogen from escaping, the pouch must be sealed immediately after. The sealed pouch is then ready to be distributed to consumers, coffee shops, and supermarkets.
Relatively recent developments in machinery have helped automate the modern nitrogen flushing process so that it can occur on a large scale, making it especially popular among medium to large roasteries.
What Is Vacuum Sealing?
Vacuum sealing is also a simple, low cost way of preserving foods. It involves removing the oxygen from the packaging after the coffee has been placed inside by using a machine to suck out the air. Immediately after, the pouch is sealed to prevent oxygen from reentering. Unlike nitrogen flushing, there is no air left between the pouch and the coffee.
Vacuum sealing is an effective way of prolonging the shelf life of coffee because it’s completely airtight, which helps to reduce the chances of contamination occurring during storage, transfer, and handling. As well as being hygienic, the absence of air around the contents means that it takes up minimal space when stored or transported.
In his pioneering book on coffee roasting, Scott Rao writes that vacuum sealed bags “greatly limit oxidation” helping to “slow the rate of flavour degradation”. For green, unroasted coffee beans, he says that it’s the “best available method of packaging” because it “protects the beans from moisture, odours, and oxygen”, and therefore “slows down the ageing process”.
Vacuum sealed bags often include a degassing valve to prevent CO2 from building up within the bag and causing it to rupture. A degassing valve is a one-way vent that allows CO2 to escape without letting oxygen enter. In the absence of a degassing valve, the roasted coffee needs between 24 and 48 hours to degas before it’s vacuum sealed.
For those who choose to freeze their roasted coffee, vacuum sealing is a popular way of containing it. It keeps the coffee moisture-free, creating a dark environment free of temperature fluctuations and air movement.
Head-To-Head: Nitrogen Flushing Vs. Vacuum Sealing
There are various pros and cons to nitrogen flushing and vacuum sealing. Before proceeding with either option, specialty coffee roasters should assess each method and decide which one will work best for them.
After coffee is roasted, the enemies of freshness are external factors such as moisture, light, and oxygen. When exposed to these external factors for too long, lipids (fats and oils) break down into oligo-fatty acids, causing the flavours in the cup to become obscured.
Both vacuum sealing and nitrogen flushing are highly effective at preserving the freshness of roasted coffee and extending its shelf life. By being airtight, they stop external factors from entering, helping to slow the rate of staling.
However, it’s important to note that with vacuum sealing, a small percentage of oxygen always remains. While it’s nowhere near the levels found in the atmosphere, over time, it can cause the coffee to lose its freshness.
Whether distributing roasted coffee to a local café or to customers on the other side of the world, it’s more than likely that anything you produce will spend at least some time in transit. For that reason, roasters need to ensure that their coffee is able to withstand a series of bumps, jolts, and knocks without being affected.
Because nitrogen flushing substitutes the oxygen it displaces with nitrogen gas, a cushion of air remains around the coffee. This makes it more resilient during long periods of time spent in transit than vacuum sealed coffee, in which the beans are in permanent contact with the surrounding packaging.
Cost & Ease Of Use
Both methods of packaging coffee are relatively cost-effective and simple to put into place. The development of machines have made the process quicker and more reliable over the years, helping to cut down the amount of time it takes to complete each bag of coffee.
As mentioned earlier, the inclusion of degassing valves can speed up the process of vacuum sealing because it means roasters don’t have to wait for the beans to degas before packaging them. It also limits the risk of the bags rupturing due to a buildup of CO2.
As a specialty coffee roaster, it’s crucial that all the hard work and effort that goes into creating quality coffee is not affected by poor packaging decisions. Both nitrogen flushing and vacuum sealing are effective ways of ensuring your coffee remains fresh for as long as possible, helping to limit exposure to oxygen and slow down the rate of staling.
In addition to your preferred packaging method, it’s also important to choose the right materials for your pouches. At MTPak Coffee, we offer a range of sustainable coffee pouches with the option of additional components, from degassing valves to resealable zippers.
For more information on our sustainable coffee packaging, contact our team here.
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