By Jan Lievens
I mentioned in one of my previous articles that the last 5% of the timing in your product cycle is important. Fact.
There really seems to be a problem for many people to see and understand exactly what the importance of this statement is. Do you realise and understand that you (the farmer) produce blood, sweat, and tears, often with lots of stress as well, for over 8 to 9 months to produce the best possible products on the vine, orchard, bush, or field?
In the process, nature too throws all kinds of curved cricket balls at you: pests, climate change, rain, often when you really do not need it, insects – the works!
Then you have all kinds of gurus that come and tell you what and what not to do, fancy products, of course only the ones that are allowed, plenty of myths, again: the ‘Full Monty’.
And, yes, they all have their place in the preharvest scene, of course.
But if you really must start believing one thing – it is that when you grow the near perfect product, the last 5 percent of your efforts sit in the postharvest trajectory after you cut the umbilical cord of your fruit. Fact.
Ninety-nine percent of the farm income depends not only solely on what you do in 24 to 48 hours after you did that; I can tell you it starts within minutes after your harvest. Fact.
Now, I am really going to throw a battery of cats among the pigeons…
Fact, and for the last time, please take note: cold rooms DO NOT maintain RH levels. Cold room panels are usually made from a closed-cell structure steel plate glued on both sides of a closed-cell product that is the insulation.
It has no properties to enhance, create or maintain RH levels in your rooms and, the refrigeration systems get the moisture out of the atmosphere – and your product. Period. It is simple, basic physics.
A lot has been 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 ridiculously fast time.
Firstly, that is all good and well, but the rule of thumb seems to be forgotten here; an uncooled table grape deteriorates in an hour at 32°C, as much as in a day at 4°C, or a week at 0° C. That means that the timing from harvest until it reaches the cold room is of utmost importance.
Secondly, what is the RH in your precoolers when you start without fruit inside? Has this been accurately measured and recorded? Where are the records kept? What do you do with the readings?
Thirdly, what is the core temperature of your product after precooling? Is it even over the whole line? Has this been accurately measured and recorded? Where are the records kept? What do you do with the readings?
Fourthly, did you balance the temperature between the precooled product and the temperature in the packhouse? Has this been accurately measured and recorded? Where are the records kept? What do you do with the readings?
Fifthly, 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” – whoever that might be, only measure the outside boxes, ie the easiest cooling targets? Has this been accurately measured and recorded? Where are the records kept? What do you do with the readings?
That brings us to remarkably interesting discussion points in our industry.
On the first issue, it is 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 the cooling tunnel are too long, it does not really matter what the “fast” cooling time is. Your product is damaged, and that damage is irreversible.
Some farms still have >7 hours, and far more in some instances, delay time between harvest and the arrival at the central cooling facilities, often not precooled correctly with too elevated temperatures, too high wind speeds with too low RH, often still not precooling at all.
Then the industry will have to start realising that you still cool like forty years ago with, at that stage, four to five cultivars and that you now have sixty-five cultivars to work with. To tell you the truth, the one-sided cooling regime is for many new varieties a death penalty.
On the second issue, it is again amazingly simple – ninety-nine percent never ever measured that.
“Over forty years of debate and tug of wars between various interest groups, and you still have a disaster deluxe on your hands.”
The third and fourth issues are also simple too – many do not do this.
On the fifth issue, it is even simpler. If the core temperature of your “hottest” box is above the required core temperature, it is a potential recipe for disaster. This is not a myth but the simple reality: A marine container is not designed to cool the product down; it is designed to keep the product cool.
I recently received TempTale graphs on various “real” table grape shipments where the return air was, for over 14 days (sic), well over four degrees C, starting from close to ten degrees 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 is simply deadly. And guess what? The cold room released the shipment for export after authorities “measured” zero point 8 degrees on the one side of the pallet.
And should I mention the carton and inner packaging debacle? Really?
Over forty years of debate and tug of wars between various interest groups, and you still have a disaster deluxe on your hands? Every season? Serious? Surely, we are smarter than that? Or maybe not?
And why not simply work together with people to get to a proper airflow system for all cartons in the country, regardless of the structural box design? Recently I was introduced to a “new” design, which is going to be evaluated soon. Again, with obvious flaws that can be addressed and rectified if people would just learn how to work together and learn how to use available knowledge.
Let us be honest, you can hide this all you want under the biggest stones even Hercules cannot move, your competitors from all the other grape-producing countries are laughing themselves to a standstill.
We have some of the best possible grown-quality on the planet, but you must preserve that quality after harvest to get it to market and to create the best possible chance to sell it. All that is described above kills your shelf-life = quality, and that is exactly where they thrive on.
I just wonder, for how long the industry is going to keep putting its head in the sand. There clearly is a problem, in fact a whole bunch of problems and no matter how many studies you try to do and how much money you throw at further theoretical exercises, if it is not getting implemented, to be frank, I regard it as complete and utter time wasting.
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 implementing knowledge in the field on a practical level at the farms.
It’s time the industry changes its attitude and approach to the last five percent of the process. Let us first tackle the problem at the farm level and then at central cooling units. I am prepared to share our knowledge accumulated in a practical way over the years.
Stop wasting time and money, become organised and start doing the right thing, it is in your own interest.
As a last thought of the day after your read this article, note this: when your product is damaged in the postharvest cycle, that damage is irreversible and cumulative, and it will show up during the transit period. Fact.
Facts are indeed stubborn, but not doing anything about it is plain and simply irresponsible.
About Jan Lievens
Jan Lievens, born in Belgium, is a graduate civil engineering(B) and international senior consultant for engineered applied postharvest technology at Humiditas South Africa. With over 20 years of experience in this field, he is widely regarded as a specialist in the fruit-, vegetable- and flower industry with regards to humidity, airborne bacteria and ethylene removal, both locally and internationally. Furthermore, he also designed airflow-friendly packaging systems for the industry with proven results.