Laws of nature don’t change

Laws of nature don’t change

Jan Lievens, senior consultant on applied postharvest technologies at UTE South Africa

When you come to grips on how nature works and respect the fact that nature never breaks her own laws, you are getting there.

But it took me nearly 25 years of dedicated and stubborn perseverance to come to a point where you finally understand what exactly nature does in postharvest.

Kees Nijssen, process sales leader at Datalogic and an expert on cooling with high humidity in one process, once said, “Jan, humidity can make or break a farm...” And he was right. Two weeks ago, I visited a big stone-fruit packhouse where so-called specialists installed a relative-humidity (RH) system in the cold rooms. They even had fancy electronic measuring displays in the machine room that indicated that the rooms were at 95% RH (the ratio of the partial pressure of water vapour to the equilibrium vapour pressure of water at a given temperature).

It is a poor workman who blames his tools.

Going into the specific cold rooms, as we walked into four of them, and measuring the RH in the various rooms at positions where the RH levels are important, in other words close to the fruit, we measured between 62% and 68% RH. Apart from that, the system also continuously sprayed unfiltered water into the rooms with devastating results: There were fungal deposits in all corners of the room and dried out and shrivelled fruit on top of that.

Water on fruit is a recipe for disaster. Only marketers use water drops on fruit in their promotional pictures to show freshness. If there is water on your fruit during the postharvest process – drops, mist or in any other form – you are in trouble. Big time.

Also read: Continuing the conversation on reducing postharvest fruit losses

Due to our never-ending endeavours to pressurise the industry to at least take notice of the importance of RH during the postharvest treatment and the diligence with which we kept doing that over the last decades, unfortunately, there have been so-called specialists that started selling machines rather than solutions. And when you start selling machines instead of solutions based on knowledge, the phrase ‘a little learning is a dangerous thing’ does come to mind.

Unfortunately, the farmer is almost always the victim, because he often does not fully understand how difficult this matter really is.

When I explain applied postharvest in my seminars, I try to explain in a fun and easy way how Mother Nature works and what the consequences are if you do not recognise that fact. But before you can do that, you must understand the matter completely. It is also important to understand that ‘an ounce of prevention is worth a pound of cure’.

Rather start talking to the right people from the outset; people who are dedicated to the subject and only sell innovative solutions to complex matters and problems. 



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