You roast this amazing coffee, and then what? How do you preserve the freshness and make the flavor last? Will your customers have a good experience with your coffee three weeks down the road? As you may know, like other perishable products, the loss or gain of oxygen and carbon dioxide can rob coffee of its flavor and aromatic characteristics. External aromas and odors can also add undesirable flavors, ultimately degrading the quality of the beans. Freshness is an essential factor when referring to roasted coffee quality since it will have an effect on the taste of coffee and therefore customer satisfaction.
Bearing in mind that packaging is what protects coffee from external gases, selecting the right type will have a direct effect on the preservation of quality and freshness. According to Mark Howley, Chairman and CEO of Pacific Bag (PBI), “Coffee is adversely affected by oxidative rancidity. It is generally believed coffee taste will degrade within 10-14 days after roasting if coffee is exposed to oxygen. Packaging has a huge impact or effect on quality if distribution time extends beyond a week or so.” Moreover, according to Coffee Analysts “The rate of coffee staling will depend upon the amount of contact with oxygen. Conditions of heat and added moisture will accelerate staling. Moisture-resistant sealed packaging with a minimum of oxygen content is the key to coffee shelf life.”1 For this reason, if your goal is increasing shelf life, some essential factors to take into consideration are: the materials of the packaging, the type of valve, and degassing.
Materials – Select Wisely
Packaging materials vary from metal cans to paper tin tie through polyester, or aluminum foil bags. According to Joy Weedon, Marketing and Sales Manager at Pack Plus Converting Corp, “Our packaging ranges from low-barrier to high-barrier material depending on the shelf life one requires. For instance, tin tie paper bags are used mainly for everyday at the shop while higher-barrier foil packaging allows roasters to pre-pack coffee for display on the retail shelf whether at their own shop or at the local grocery store.”
According to Chris Burger, Coffee Market Manager at Fres-co System USA, Inc. “The key to fresh coffee is using the correct barrier materials for the desired shelf-life. The typical retail bag requires a layer of thin aluminum to prevent oxygen from entering into the bags.” In addition, Weedon adds, “Foil material is an effective barrier against mainly light, oxygen and moisture and is the preferred choice of many coffee roasters.” The packaging material should be selected taking into account the shelf life you desire. Ask yourself: Will the coffee be sold at your shop or in grocery stores? What is the usual turnover of inventory? Will the material be resistant to endure all the handling involved in the logistics?
Degassing – Just Let It Out
After roasting, coffee releases CO2, up to 1000 cc per pound. Fresh whole beans will release gases for several weeks after roasting. While many roasters might allow their coffee to de-gas in storage by letting it sit for a period of time before packaging, valves allow you to package your roasted coffee right away. The main purpose of a valve is to allow these gases to escape, without allowing any external gases, such as oxygen, to come in.
Multiple factors should be taken into account when selecting valves. According to Burger, “It is critical to understand the performance of the valve selected. Where is it made? What is the opening and closing pressure? What is the failure rate? Many times a bag can be a leaker directly through the valve causing coffee to stale in weeks.”
According to Nick Greco, Global Segment Manager at Avery Dennison Designed and Engineered Solutions, “Flexis technology has several advantages over conventional hard valve technology. Flexis valves allow for up to a 30 percent increase in application throughput and a 30 percent – 50 percent product purchase advantage over hard valves. Plus, they offer exceptional performance characteristics. Tests conducted in conjunction with a major university show that the valves maintain less than 2 percent residual oxygen for 24 months, equaling the reliability of hard button valves.”
Modified Atmospheric Packaging (M.A.P.), also known as Nitrogen or Gas Flushing, refers to a process where a roaster, within a few hours of roasting, evacuates the bag of all oxygen, flushes it with inert gas such as nitrogen to fill the voids that used to be taken up by air, and then thermally seals the bag. This process is recommended when considering expansion into grocery stores since increasing shelf life and preserving quality are a priority.
According to Burger, “There have been many studies that show coffee that has been gas flushed remains fresher longer as compared to coffee that has not been gas flushed. Many believe that simply putting fresh coffee into a bag and sealing it will give 6 months plus of shelf life. The issue is the oxygen in the coffee bag at time of sealing will start to stale the coffee and shorten the shelf life.”
Considering that it is recommended to have no more than 3% oxygen content in the package1, it is important to select wisely when purchasing and selecting packaging materials and methods. If you are only planning to sell your roasted coffee in your stores, tin tie paper bags can be the most cost-effective option. However, if your primary purpose is increasing shelf life, you will need to take into account the usage of a high-barrier material, effective valves, and Nitrogen Flushing methods to increase the preserve the quality and flavor of the beans.
1Coffee Analysts, Coffee Packaging and Shelf life, March 29th 2011, Retrieved September 24, 2012. From http://www.coffeeanalysts.com/2011/03/coffee-packaging-and-shelf-life/
By Karl Seidel – Cablevey
Ahhh… chemistry! In these days of political revelry combined with good old-fashioned religion I never tire of hearing opinions based on…nothing but hot air. It is interesting, then, to hear about nitrogen displacing oxygen while processing and packaging coffee – ground coffee in particular.
A few percentage points of oxygen one way or the other can kill a human. Yet displacing oxygen with nitrogen in a sealed bag can increase the life of your coffee – for a good while. Based on talking with Chris Honeyman & Jay Isais at The Coffee Bean and Tea Leaf, “oxygen is the biggest degrader to food.”
At sea level there are normal states of oxygen at 21%, nitrogen at 78% and the leftover 1% is Argon. You will notice it’s harder to breathe that oxygen at higher altitudes and you’ll get the bends without enough oxygen when you’re scuba diving. What you want to consider is what happens to your roasted coffee after it leaves your place and gets to a customer’s location. This is because that is where they open the bag and get the aroma-effect. If your coffee is stale – and ground coffee stales more quickly than whole bean coffee – that is what your customer will remember!
I was curious about how the nitrogen gets in the bag and has the stated effect of keeping the coffee from staling because I know when the coffee empties out of conveyors it lands someplace – a silo or other way-station before getting bagged. The idea is to get it someplace, then let it rest and off-gas. After this point, the nitrogen is injected into the process.
Typically, the nitrogen is going to be injected from below to force the oxygen up and out of the beans before they are put in a bag. This is the tricky part – the oxygen can be sucked out while adding a blast of nitrogen – and sometimes this occurs by keeping the coffee sealed in a smaller area/chamber while it gets into the bag.
At this point, an epic battle ensues. Once the bag is sealed the oxygen is still in there but the Carbon Dioxide from the off-gassing and the nitrogen “flush” is displacing the oxygen using a combination of the heavier weight of the two inert gases. Nitrogen and Carbon Dioxide fight it out and the oxygen is pushed out through the one-way valve in the bag you typically use for packaging ground coffee. Phew!
At the end of all this sucking and blowing, and getting the coffee into the bags, how much of the 21% of oxygen has been displaced by the nitrogen? Good question! The goal is all but 2 to 3%… and that seems to be the standard roasters shoot for in this process.
Whole bean coffee is a less contentious struggle and knocking the nitrogen down to single digits is OK.
Most roasters big enough to be doing a nitrogen flush will consider three basic methods. The first uses cylinders that are portable which will last for a couple of days and need regular replacement. The next size up company will use a bulk tank that is filled as often as needed by a nitrogen-carrying truck. And if you are the right size (bigger) you will get yourself a nitrogen-generator/compressor and scrub the air to make it yourself! In the end, all of these methods will extend the shelf life of your coffee creating longer selling cycles.
Packaging Resource Guide
Avery Dennison Designed and Engineered Solutions
Fres-co System USA, Inc.
Pacific Bag, Inc.
Pack Plus Converting