Procedures for cooling sensitive fruit.

It is well known that sensitive fruit products suffer from increased levels of Internal Browning if cooled too quickly. Eg Pink Lady apples must be step wise cooled. Stone-fruit cooled to quickly suffers badly and increases shrinkage. QTee pears appear to suffer the same fate.

The most affective system when harvesting in hot conditions is to drench the fruit with cool water for a few minutes. This can reduce the field temperature by 5/10° without causing any harm to the product. In addition, when placed into cold storage the water on the fruit acts a conduit for removing heat without moisture loss to the fruit.

In relation to QTEE, I feel, the procedure adopted of rapid cooling is totally wrong.

The way to do this is, stepwise cooling. This means that you drop the field temperature in 5 Degrees Celsius increments until the desired temperature is achieved with the last 5 degrees taking the longest time. (ie 2-3 days)

If you install AiroFresh® within the cooling chamber, there will be no ripening taking place as the ethylene is destroyed by the AiroFresh® unit.

The most important factor with AiroFresh®, apart from correct placement, is adequate constant airflow at all times.

There are two ways to achieve this;

  1. Have your evaporators fans on continuous airflow, which in fact increases the humidity within the room.
  2. If your evaporators are cycling, then install an additional fan at the back to the rooms so that airflow is directed back to the evaporators and the AiroFresh® unit.This is critically important no matter what product is placed under AiroFresh®, without adequate airflow they do not function to their full capacity.

I feel confident that you will achieve much better results with Qtee if you follow these guidelines.

The same principle applies to all other products, except some apples are not affected by rapid cooling. Ie Granny Smith, Red delicious.

In the cooling process it is important to understand that the cooling is by conduction, that means the outside is cooled reasonably quickly, but the centre remains quite hot and hence this can induce ripening, particularly in bins with plastic liners. Even the centre of the bin remains hot for some time.

The information that I sent in relation to Pink Lady stored under CA and AiroFresh® for 10 months, speaks for itself and when compared to Fruit treated with1MCP, the flavour profile is significantly reduced with 1MCP. (Refer to the French Research which clearly shows this) Moisture loss is higher, as are rots and moulds with 1MCP.

Hoping that this is helpful to you and I would be interested in knowing the outcomes should you proceed down the AiroFresh® path.

Since leaving Berlin two major cold store operators in Australia are installing AiroFresh® in all their rooms this season, following very successful trial without 1MCP. 10 rooms in one facility and 11 in another ranging between 600 and 1100 bins per room.

Please contact me if you need anything else.

Kind regards


WA Australia

Giston Consulting Services