How Extra FRESH® works



Understanding ethylene!
The ethylene molecule is very reactive and is readily oxidized into a state that will not do damage to produce. There are several ways that may be used to remove ethylene from produce storage areas. One of the simplest and safest methods is to oxidize it with potassium permanganate. (For those of you who, like me, enjoy chemistry, a link to the reaction is given at the bottom of this page). This reaction can remove ethylene to very low levels. Potassium permanganate (KMnO4) is used in a number of familiar applications, such as in drinking water treatment systems.

Composition
We chose to use potassium permanganate as our oxidizer, we then needed to find a way to make it the most available for reacting with the ethylene gas in our refrigerator. We needed a support medium that will allow the ethylene to contact the oxidizer so it may be reacted away.

The granules within your Extra FRESH® disc have been used as a commercial product in the fruit and vegetable industry throughout the world for more than 30 years. It has a proven track record of keeping fruit and vegetables fresh and is now available for you to use at home.

BI-ON® is the name of our permanganate pellet. BI-ON® is a disposable purifier generated from a mixture of natural clays and potassium permanganate. One of the natural clays is called Zeolite, which is a pure form of volcanic ash that has a very high surface area, providing an ideal substrate for the ethylene oxidation to occur.

Natural zeolite is often used as an odour absorber and a humidity stabiliser in refrigerators, closets, and automobiles. The very high surface area traps odour molecules and absorbs water when humidity is too high - releasing it back into the atmosphere when it gets too dry. Of course, the zeolite used in your Extra FRESH® disc serves those purposes, but its function as a support medium for removing ethylene is its main purpose.

The zeolite used in Extra FRESH® is from an exceptionally high quality deposit. After the crushing and grading of the zeolite, there are no fines and virtually no dusting. The potassium permanganate is applied to the zeolite using a patented process that lays the active chemical on the surface uniformly all the way to the center of the zeolite. The resulting product has the highest reactive chemical, and the best cationic exchange capacity of any in the industry.

Packaging
The KMnO4 coated zeolite is then packaged in Tyvek packets that are water resistant, but are highly permeable to ethylene. It contains the zeolite and prevents any fines from getting out of the disc and onto your produce.

Fridge manufacturers have improved their cooling & humidity but...
While refrigeration and humidity slow the decay of your fruits and vegetables, they don't halt the production of harmful ethylene gas, whose effects can be quick and destructive. Ethylene gas levels as low as 1 part per million (ppm) can destroy an entire shipment of produce in a single day by accelerating the ripening process and making produce vulnerable to disease - imagine the damage it does to the food in your refrigerator!

Because plants produce ethylene even after they are harvested, and are exposed to external sources of ethylene, confined storage areas, refrigerators and freezers are full of the deadly gas.

You've seen the effects of ethylene gas damage many times: shrink (fresh produce and flower bulbs); russet spotting (leafy vegetables and eggplants); yellowing (cucumbers, broccoli and brussel sprouts); odour (garlic and onions); wilting (vegetables and cut flowers); scald and loss of crunch (apples); and rind breakdown (citrus).



Design
A very important feature in the Extra FRESH® disc is its design. In order to maintain the very low concentrations of ethylene necessary to protect the produce in your refrigerator, there has to be a lot of contact between the air and the potassium permanganate. If the zeolite packet were dropped into your produce crisper as is, it would quickly find its way to the bottom of the drawer.

The venting design on both the front and back of the disc prevents cutting off the circulation that is required for its effectiveness. It is unlikely that anything could inadvertently fall onto the disc that would totally restrict air flow. Ideally, the disc should be placed in separate drawers to further limit the possibility that restricted air flow would reduce its effectiveness. By having two points of possible contact between the ethylene in the air and the KMnO4 on the zeolite, the lowest possible level of ethylene can be maintained.

Time for Replacement
The reaction between the ethylene and potassium permanganate oxidizes the ethylene away and, or course, reduces the potassium permanganate away, too. The amount of potassium permanganate available will last at least 3 months in most home refrigerators. After 3 months you should replace the Extra FRESH® disc.

Want to know the chemistry behind it all? See the chemistry in action.