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SHELF LIFE: IT'S NOT FRESH UNLESS IT'S FLUSHED


Gas flushing in the food industry has become all but ubiquitous in our modern age of high demand for snack foods and extended shelf life of consumable commodities in general. Unsurprisingly, responsible cannabis producers have followed suit. Long gone are the days of simply vacuum sealing, or even storing cannabis in clear plastic sandwich bags (gasp!), as producers have recognized the growing need to keep their cannabis fresher, longer.


WHAT IS SHELF LIFE AND HOW IS IT DETERMINED?

According to The Institute of Food Science and Technology shelf life is “the period of time during which the food product will remain safe; and be certain to retain its desired sensory, chemical, physical, microbiological, and functional characteristics.” So, both safety and quality are important aspects of shelf life. But in the food industry, which has preceded the cannabis industry by decades if not centuries, there is no universal protocol for the determination of shelf life.


This fact remains true in the emerging cannabis industry. Currently, there are no “use by” dates associated with cannabis flower. And the freshness of cannabis edibles is often based on the other ingredients, like eggs or milk in brownies. What we do know, however, is that the packaging of cannabis products can greatly affect the quality, and therefore, the shelf life.


The composition of the air within a container and the permeability of that container used to store cannabis can influence oxygen degradation and bacterial growth. Oxygen is one of the top four spoilers of cannabis (along with light, heat, and moisture), so the less oxygen that touches cannabis after curing, the better. And while the industry is still working on discovering optimal oxygen levels in cannabis packaging, a good guideline to consider in the meantime would be less than 6%, which is the amount usually accepted for fruits and vegetables.


If you’re not sure how to know the oxygen content of your packaged cannabis, a Modified Atmosphere Gas Analyzer (or simply an Oxygen Analyzer) can help. These devices are designed to quickly report gas percentage levels in sealed packages. They work by inserting a small needle that detects thermal or magnetic changes and translates them into gas level calculations.


You might think that inserting a needle into a package would ruin the hermetic seal, but these analyzers use a handy little gadget to avoid this potential problem. It’s called a sticky nickel. These small adhesive dots create their own seal that functions during and remains after the insertion of the needle, allowing the package to maintain its sealed integrity. Oxygen analyzers and sticky nickels are widely available online, and for a relatively small investment cannabis producers can purchase them for use during packaging to ensure proper oxygen levels, which enhances quality control.


WHAT IS GAS FLUSHING?

Did you know that in the 18th century merchants would place a lit candle in a barrel full of biscuits before closing the lid? The candle used up the available oxygen before dying out, and therefore protected the baked goods from excess oxidation during transport and storage. This may have been one of the first examples of what we now call Gas Flushing.


Gas Flushing is also known as Modified Atmosphere Packaging (MAP), Protective Atmosphere Packaging (PAP) and Reduced Oxygen Packaging (ROP). One of the most common gasses used for gas flushing is nitrogen (N2).


Nitrogen is the fifth most abundant gas in the universe, and it makes up approximately 78% of the air we breathe. That equates to about 4,000 trillion tons of nitrogen in our atmosphere alone.

Fractional distillation is one method used to pull nitrogen out of ambient air. It entails cooling the air, isolating the nitrogen, separating it from the air, and collecting it. It’s like cooling a lake in order to slow down the fish so you can pluck them right out of the water.

Another method is the use of nitrogen generators, which separate N2 molecules from the air by using a membrane that allows oxygen, water vapor, and other unwanted materials to permeate out as the pure nitrogen is collected. Nitrogen generators are basically air filters, like the ones you use in your car or your home, but more high-tech.


Almost any container can be gas flushed. Mason jars, tin cans, rigid and flexible plastic packaging are all legitimate candidates. But each has its own drawbacks, especially when it comes to environmental impacts. Although glass, tin, and some rigid plastics are highly recyclable, their life-cycles may not be more sustainable than flexible plastic packaging. And as we learned in a previous post on recyclability of packaging materials, recyclability is a poor indicator of environmental impacts. It’s in the entire life-cycle of a product that we will find a better understanding of how it impacts our environment.


GAS FLUSHING VS VACUUM SEALING: WHAT’S THE DIFFERENCE?

Gas flushing with nitrogen and other gasses is not the same as vacuum sealing, although the two processes can be used together and both end with a proper heat seal.


Vacuum sealing is a process in which a certain volume of ambient air is removed from a package before it is sealed. Ambient air is made of approximately 78% nitrogen, 21% oxygen, and 1% carbon dioxide. These numbers stay the same when a package is vacuum sealed, because no matter how tightly you vacuum seal there is still air in the package and the makeup of the air has not been altered.


On the other hand, gas flushing is a process which allows for the gas percentages in a package to be altered. When nitrogen is injected into a package, it forces the denser oxygen out. And because of its relatively inert properties (it does not react with other compounds in the air or with food) nitrogen is commonly used to significantly slow the process of food spoilage.

Vacuum sealing can result in a crushed product if too much air is removed because the packaging collapses on the product and squeezes it. This may not be a big deal for the average person vacuum sealing their next week’s meals, but it is a huge no-no for packaging cannabis. Squeezing cannabis in this way destroys the delicate trichomes.


Gas Flushing rarely, if ever, results in a crushed product. In fact, many snack foods like potato chips are gas flushed in order to maintain freshness of the product, but also to provide a “pillow pack” effect so the delicate food cannot be destroyed before being consumed. Just like potato chips, cannabis enjoys a comfy pillow pack that protects trichomes from being crushed and destroyed.


When a low permeable package is gas flushed and properly heat-sealed the modified atmosphere inside is contained, and ambient air from outside the package is kept out; and this can dramatically increase the shelf life of a product.

WHAT INDUSTRIES USE GAS FLUSHING? WHAT ARE SOME EXAMPLES OF GAS-FLUSHED PRODUCTS?

The food industry uses gas flushing in a myriad of packaging materials on an epic scale. Products from cheese to crackers to meats and vegetables are packaged in modified atmospheres, and each atmosphere is unique to the product it surrounds. Take cheese for an example. Hard cheeses with low water content are susceptible to mold, but softer cheeses with higher water content may be affected by bacteria. So hard cheeses are packaged with higher levels of carbon dioxide (CO2), even up to 100%, whereas soft cheeses are packaged with CO2 levels up to 40% and nitrogen makes up the difference. These modified atmospheres can keep hard cheeses fresh up to 10 weeks and soft cheeses up to 3 weeks.

In the case of meats, the atmosphere is completely different. In order to keep meat looking red, for example, the atmosphere inside the package must contain carbon monoxide (CO).

It would seem that our modern era is obsessed with the benefits of gas flushing. The food industry can’t get enough of it; the healthcare industry uses it for packaging medical devices; even the tech industry knows the benefits of gas flushing for keeping things like SMD components from corrosion during transport and storage. And the cannabis industry is no exception. Here at Rogue Pouch we endorse gas flushing for packaging cannabis products, and we are certainly not the only ones lauding the benefits of this type of modified atmosphere packaging in our industry. A quick internet search will show any interested cannabis producer that this method is gaining ground – and for good reason.

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