Frequently asked questions about degreening citrus

What is the system and chemical used for colouring fruit?

The system for colouring fruit is called degreening, the chemical used is ethylene and the method used is called trickle degreening.

What are the brown marks on the skin of fruit after they come out of the degreening room?

This is a condition known as 'degreening burn' and is believed to be associated with the anthracnose fungus. Several factors are known to predispose the fruit to damage. These include picking fruit when immature, abnormal degreening conditions and moisture and nutrient imbalances close to harvest. Growth of the anthracnose fungus in the skin is triggered by ethylene during the degreening process. Some of the marking develops during degreening but it often occurs during and after packing.

How much ethylene do I use for degreening citrus?

The concentration of ethylene required is between 3 and 10 parts per million of the fresh air intake. Air intake is between 1% and 2% of the room volume per minute.