Speed syndrome in cooling fruit..

.By Jan Lievens of UTE
The last 5% of your timing in your product cycle is important, yet there seems to be a problem for a lot of people to understand the importance is of this statement…

JL001

If the core temperature of your ‘hottest’ box is above the required core temperature, it’s a potential recipe for disaster. Image credit: My Fancy Pantry

Now, I’m really going to throw a battery of cats among the pigeons.

There is a vast difference between making something cold, and cooling fruit...

A lot has, and still is, being said about the time that is needed to cool grapes down to the prescribed temperatures of +0.8° C or even still -0.5°C.

Everybody wants to cool down as fast as possible and looks at the clock to get the forced air cooling tunnel time down to a sometimes-ridiculous fast time. Now, that’s all good and well but in the first place, the rule of thumb seems to have been be forgotten here; an un-cooled table grape deteriorates in an hour at 32°C as much as in a day at 4°C or a week at 0° C.

Secondly, did you ever measure, and do all your boxes get measured on the correct end temperature on every position in the tunnel during and at the so-called ‘end of the cooling process’?

Or do you, or ‘they’, whomever that might be, only measure the outside boxes, in other words the easiest cooling targets?

That brings us to some interesting discussion points in our industry.

On the first issue, it’s simple: You can talk all you want about the speed of your fast-forced air cooling facility for as long as you want, if your delay and path between harvest and cooling tunnel is too long, it doesn’t really matter what the ‘fast’ cooling time is. Your product is damaged, and that damage is irreversible.

Some farms still have more than seven hours (or far more in some instances) delay between harvest and the arrival at the central cooling facilities, often not pre-cooled correctly with too high temperatures, too high wind speeds with too low relative humidity (RH), often still not pre-cooling at all.

On the second issue, it’s even simpler. If the core temperature of your ‘hottest’ box is above the required core temperature, it’s a potential recipe for disaster. A marine container is not designed to cool product down, it’s designed to keep product cool.

JL002A marine container is not designed to cool product down, it’s designed to keep product cool. Image credit: Boxhub

I recently received TempTale graphs on various ‘real’ table grape shipments, where the return air was for over 14 days well over 4°C, starting from close to 10°C. Trust me, not from one container but from a whole battery of containers. Apart from me nearly having a heart attack and tears in my eyes, it’s simply deadly. And that is mainly down to inadequate carton design and inefficient forced cooling tunnel designs.

I just wonder for how long the industry is going to keep putting its head in the sand. There clearly is a problem, no matter how many studies you try to do and how much money you throw at further theoretical exercises.

In 2012, I already stated at an International Research Congress in Cape Town that there is a huge gap between our fantastic scientists and researchers when it comes down to imparting and implementing knowledge in the field on a practical level at the farms.

It is time that the industry changes its attitude and approach to the last 5% of the process, since it is 99% of your income.

Let's first tackle the problem at farm level and then at central cooling units.

Click here to read the issue of Cold Link Africa

 


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