Unexpected Freeaire System Benefits: Ethylene Gas Dispersion (Apples and Carrots Stored Together, Happily)

SignfreshfruitvegetablesFreeaire systems provide many benefits, including:

  • Reduced energy use saves money.
  • Reduced energy consumption leads to reduction in a business’s ‘carbon footprint’.
  • Less system run time means reduced wear and tear and maintenance for conventional refrigeration equipment.

But that’s not all.

In the area of  the unexpected benefits, bringing fresh, filtered outside air into a cooler can help store fresh produce for extended periods, and also allows for diverse products to be stored together.

A walk in cooler is a closed environment, the atmosphere is usually stale, musty and somewhat unpleasant.  When fresh produce is stored in such an enclosed space, the ethylene gas given off by certain fruits and vegetables can accelerate ripening, with detrimental consequences:

Ethylene Production Classification Of Some Fruits And Vegetables

Ethylene is a natural plant growth regulator, produced by “climacteric fruit”, such as apples, tomatoes and bananas (see Table 3). It is a colorless gas that is thought to coordinate the ripening of these fruits. Ethylene gas is also produced by tractors and other equipment with internal combustion engines and can accelerate ripening of climacteric fruit. Ethylene can have a number of deleterious effects on other products. These include faster yellowing and senecence of leafy vegetables, browning reactions such as russet spotting on lettuce leaves, development of bitterness in carrots, and sprouting of potatoes.  (Source: Cornell University Ecogardening Factsheet #19, Summer 1999)

When a walk in cooler has a Freeaire Polar PowerTM package installed, the system uses highly filtered, cold outside air as a cooling agent and turns off evaporator fans and condensing units for weeks or even months at a time. The air that can be brought in will vary in relative humidity, from very moist to very dry.  The Freeaire system uses a combination temperature and (optional) humidity sensors to control the use of outside air and to regulate humidity.

Real world examples:

  • One Freeaire owner supplemented the moisture inside a walk-in cooler full of carrots and other root crops with a humidifier that added enough moisture to maintain a temperature of 33°F with a relative humidity of almost 95%, even when using the extremely dry air of mid-winter.
  • Another owner reported excellent results over a winter of storing carrots and apples together, a combination that is usually unsuccessful due to ethylene gas given off by the apples causing premature ripening of the other crop.

The exchange of air inside the cooler keeps the ethylene levels very low.  Additionally the air quality of many coolers has benefited from using outside air brought in by their Freeaire systems. Even coolers that smelled bad or stale and musty before due to mold spores or un-swept floors littered with food scraps can “smell as fresh as all outdoors” with a Freeaire system.

Disclaimer:  We have not formally studied or quantified the precise benefits of ethylene gas dispersion via Freeaire systems.  The anecdotal evidence presented above, however, represent real-world examples of two Freeaire system owners who have shared their experiences with us.