Egyptian citrus reaches eating maturity before it reaches full external colour. Warm autumn nights in the Delta hold chlorophyll in the peel, so the first Navel of the season can carry the required sugar and acid balance while still showing green. Buyers in the Gulf and in Europe will not take a green orange, and that gap between internal maturity and external colour is what degreening exists to close.
What degreening actually does
Ethylene applied in a controlled room breaks down chlorophyll in the flavedo and lets the underlying carotenoids show. It does not raise Brix, it does not lower acid, and it does not advance ripening in the way it does on a climacteric fruit such as mango or banana. Citrus is non-climacteric. The fruit that goes into the room at a given eating quality comes out at the same eating quality, only orange. This is worth stating plainly to a buyer, because degreening is sometimes described as ripening and it is not.
Room conditions
A degreening room runs on four variables that have to hold together. Ethylene is dosed at low concentration, commonly in the region of 1 to 5 ppm, and more is not better. Room temperature is typically held around 20 to 25 C, since colour break slows at lower temperatures and decay accelerates at higher ones. Relative humidity is kept high, around 90 to 95 percent, to prevent moisture loss and rind shrivel over what can be a two to four day cycle. Ventilation matters as much as the gas: carbon dioxide produced by the fruit has to be flushed out, or the colour response stalls and off-flavours develop. Fruit is checked daily and pulled the moment the target colour is reached, not left to run a fixed cycle.
The cost of overdoing it
Extended exposure is where degreening damages a load. Too long in the room and the calyx dries and drops, stem-end rind breakdown appears, and the fruit becomes markedly more vulnerable to green and blue mould in transit. Ethylene also accelerates senescence in the peel, which shortens the shelf life the fruit has left when it reaches your warehouse. A degreened consignment is not the same commercial product as a naturally coloured one arriving in January, and it should not be booked on the same assumption about holding time.
What to specify as a buyer
- Whether the consignment has been degreened, stated on the specification rather than discovered at arrival.
- The target colour and the tolerance, agreed with a colour reference rather than in words.
- Time in the room, which tells you more about likely rind condition than the colour itself.
- The post-degreening handling plan, since fruit coming out of a warm room needs to be cooled promptly and evenly.
- Fungicide and coating treatment, because decay pressure on degreened fruit is higher.
The maturity side of this decision, which sets the earliest defensible picking date, is covered in our note on Brix, acid and the maturity ratio. What happens to the fruit immediately afterwards is set out in pre-cooling before the reefer doors close, and degreened fruit makes that step less forgiving, not more.
For the 2026/2027 season we expect the first degreened Navel volumes to move as maturity testing clears the early blocks, with naturally coloured fruit taking over as night temperatures fall. Shipments run from Alexandria, Damietta and Sokhna on Incoterms 2020 terms, FOB or CFR as agreed.
Book early season citrus
To discuss early Navel programmes, degreening status and set points for your market, message the Nile Prime team on WhatsApp at +20 10 9911 1918.