Ingredients for Proper Ripening
 
Setting up the correct parameters to ripen any fruit is critical.  Also key is to have management instituted so that constant monitoring of the ripening process occurs.

 

Here are elements that are vital to any ripening program:

 

  • Mature fruit. Immature fruit may ripen, but typically will not have full flavor development and may not have full cosmetic appeal.  Ripening such fruit will require extended ethylene application and a longer ripening cycle.  For proper results, ripen only mature fruit!

  • Age of fruit. It is good to know the quality of the fruit to be ripened.  Age and history of conditions that the fruit has been exposed to will help in determining the proper ripening cycle.

  • Proper temperature.  Key to the ripening process is pulp, or core, temperature of fruit.  Keeping a close eye on this temperature of fruit while ripening helps to control the process and dictate the speed that the fruit ripens.  The ability to control the pulp temperature is determined by ripening room design.  The room must be able to remove heat generated by the the fruit as it ripens; fruits vary in the amount of respiration, but the highest are avocados and bananas.  

  • Time.  It is imperative not to rush the ripening process!  Increasing temperature beyond proven upper limits for a particular fruit in order to speed up ripening typically causes much more harm than benefit..."cooked" fruit, shortened shelf life, dissatisfied customers, etc.

  • Airflow. The room must have properly sized fans to facilitate air flow; if the design is forced air / pressurized, then the room system should be able to maintain the pulp temperature of interior boxes of a pallet to within a degree. If not pressurized ("conventional" rooms), then each box should be positioned on the pallet in a "cross-stack" pattern to facilitate airflow.

  • Humidity.  The relative humidity (RH%) for most fruits should be maintained at 90-95%. Improper levels will result in weight loss and cosmetic damage.

  • Carbon Dioxide / Oxygen.   As fruit ripens, it's respiration decreases the oxygen in a ripening room and emits carbon dioxide. Concentrations above 1% (10,000 ppm) will retard ripening, delay the effects of ethylene and cause quality problems. Therefore regular ventilation is required to keep carbon dioxide levels below 1%.

  • Ethylene. To trigger the fruit within a ripening room to ripen uniformly and predictably, an external source of ethylene is required for most fruits. Ethylene is a natural plant hormone that affects the growth, development, ripening, and senescence (aging) of all plants. Ethylene has been found not harmful or toxic to humans in the concentrations found in ripening rooms (typically less than 250 ppm). In fact, ethylene was used medically as a anesthetic in concentrations significantly greater than that found in a ripening room.  For more information on ethylene, please see our Resources page. Ethylene is explosive at 27,000 ppm; however, all that is required to ripen fruit is 100 - 150 ppm.  There are several sources of ethylene application systems available; the safest form is ethylene generators and concentrate.  In fact, the United Kingdom's HSE has stated in a document that "the use of cylinders of pure ethylene should be vigorously discouraged."

  • "Tight" Rooms. Ripening rooms should have a smoke test performed to check for air leaks at least once per year.  While not vital to the ripening process, this will help show where ethylene will escape and cause premature ripening in other rooms or damage to other types of fruit.  When rooms are relatively "tight" and have limited leaks, this will save on ethylene loss, refrigeration and more.

 

 

 

 

 

 

 

 

 

 

 

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