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By Jan Lievens
In simple terms, “holistic” refers to the understanding of the relationship between all parts of a whole. In problem solving, a holistic approach starts by first identifying an obstacle, then taking a step back to understand the situation.
In the fresh commodities industry, you have preharvest, postharvest and logistics as three main “blocks” that come into play.
Preharvest, which takes almost 9 months of the farmer’s time, is well covered and to be honest, our South African farmers are rated as being some of the best in the world.
There is then also nothing wrong, in most cases, with the quality of the produced fruit on the vine, orchard or in the field. So, I won’t go into detail on that part.
The logistics, once the cooled produce is on core temperature and loaded in a container, are then kicking in. There, we all know the havoc that was created last season by container availability, container freight price and shenanigans in the Cape Town harbour. This is a debate item that must be held by other specialists – maybe in another section of this publication. But it is also an important debate that will have to take place and rather sooner than later as the season is again upon us.
I want to talk on the last 24-36 hours after harvest, the postharvest part of the process. Here you only have that time slot to correctly CONDITION the quality that you have harvested.
And in that timeframe you have what we call our 10-point program – to do everything right in the correct sequence without skipping any of the issues at hand. So one simply cannot overlook any of the issues at hand and you will have to look at the detail as well.
You simply cannot look at this complete chain event in separate slices and only tackle each slice without looking at the total chain. That is what I meant by looking at the postharvest block in a holistic way.
Plenty of my articles have covered these aspects.
“Blowin in the wind” in September last year covered the airflow in the boxes. And that is just one slice of the whole chain, but one that has got a huge influence on one issue that has to be avoided in postharvest all together: CONDENSATION.
In 1998, Mark McCleery, from Mondipak at the time, and myself, designed what was going to be known as the “Filacell” carton in a (at that stage still allowed) smokey Innovation centre of Mondipak on the 2nd floor in Epping.
The hole size was determined by the cigarette box “footprint” of Briane Reynolds, director at Mondipak in that time.
We managed to make a fully “flow through” design of a 300 x 400 x 120 mm grape carton.
And we thought we invented the “nec plus ultra” which nobody did at that stage.
6 weeks later, a book arrived from UC Davis, which I ordered four months before, in the post and guess what… the book was published in 1976 and on page 13, the “ideal” carton that we designed was described in full.
So, if you want to start reinventing the wheel, remember, we have known that for nearly 5000 years that it is round. That carton, as stated, known as the “Filacell” carton, was tested in 2000 by Hortec and it simply outperformed the “traditional” cartons by two miles.
In fact, Hortec recommended that it should have been tested and implemented in the industry.
That hardly happened as those tests in some or other mysterious way “disappeared”. Over the years, tons of materials, scientific studies, research, and debates have been going backward and forward on this subject. To date, these stories are still ongoing and unfortunately, in practice on the farms, the logical proper designs are often not implemented. It is really like a tug of war is being played by some role players to the detriment of the farms.
In fact, if it wasn’t so tragic, it’s almost comical how intelligent people sit in meetings, agree on changes, and then go their own way again once they leave the room.
In 2015, when Professor Luis Luschinger came to South Africa, the above-mentioned story was noted by somebody in the audience and the exact words that Professor Luschinger said at the time are still not ready for publication even now after all these years! But he didn’t mingle his words and found it strange that the Filacell carton was never ever implemented on a big scale in the industry. He also saw huge problems with the cartons on his visit.
That is where the David and Goliath story does start taking off. We are Davids in the industry, but we have proven to be right and eventually the penny will drop and the stone will hit Goliath on the head or even somewhere else where it will hurt.
As we tried to do the best we can for the farms to their benefit. Looking at what the Goliath family is doing in this respect, one starts wondering why they are so stubborn in not wanting to implement a simple, logical principle based on nature’s laws.
In South Africa, the farms are often confronted with an added problem. Over here, still a lot of farms are dependent on cooperative or commercial central cooling companies to get their products cooled to the appropriate temperatures before shipping properly cooled produce to far away destinations.
And that is where another problem comes in: “PROPERLY COOLED”.
Often these big conglomerates are based on volume throughput, and they don’t always care about the total picture. Volume makes money, so money they will chase. Often, and more than normally should happen, the temperatures are taken on the coldest point, approved for export, and moved on to a container as there are other pallets to be cooled.
And that is where the problem comes in. Due to the “in general bad airflow designs” of the cartons and inner packaging, the coldest point will measure 0.8°C, but 1200mm further in the same pallet, we have measured temperatures from 13.8°C till >15°C. And that is due to bad airflow design.
You are not cooling “something”, you are working with living, fragile produce. From protecting fragile produce to facilitating quick, efficient cooling, we should by now all know that good box design plays a vital role towards delivering top quality conditioned produce.
To add to the problem, there are close to 15 different carton manufacturers that, in a cooperative and/or company cooling scenario, all have cartons with different designs that come in the same tunnels. Add to that different airflow patterns, different temperatures, and different inner packaging, and you have an equation that is simply “hardly solvable”.
Hence the urgent request for the industry bodies to come to a single airflow pattern to be used by all carton manufacturers.
And we are only talking about the airflow pattern, NOT the construction of the box.
At least, with a single airflow pattern, your cooling will be equal, and you will avoid a string of problems that are currently creating havoc.
Herewith some things to remember when designing your next produce box.
Carton manufacturers and dictating supermarkets and receivers don’t always have the post-harvest expertise required to fully understand the role that design plays in protecting and preserving fragile fruits and vegetables.
Sometimes they just “dictate” a design, not understanding that it harms the preserving of quality condition after harvest. Therefore, it is vital that farmers/growers and packers provide their input during the design process and start talking to the end user demanding party that they want to adhere, but want to deliver quality as well.
We have many years of experience helping farmers/growers and packers to improve their post-harvest practices and we have implemented our postharvest philosophy with great success in the industry.
There are some major factors that should be taken in consideration when designing or choosing produce cartons or other packaging:
- Type of produce you are packing, cooling, and transporting
- Size and shape
- Cooling method used on land in the cold rooms
- Transport methods
- Type of material used to construct the box
- Type and materials used for inner packaging
- Pallet construction used and the airflow construction restraints of the pallet
- If crates/cartons, punnets, and inner bags are not properly designed for the produce that is going to be in there, damage may occur
- When using plastic crates special attention should be paid to the size, shape of the vent holes and the smoothness of the edges
There are plenty of problems that can occur: skin damage from vent holes, damaged skin caused by pressure from product above, blocked hole shapes by produce etc.
With respect to the carton strength, your carton manufacturer is well placed to calculate and construct the right product for your export or local transport needs. Factors to consider include but are not limited to:
- Produce being packed
- Produce weight per carton
- Stacking height
- Pallet dimensions
Box manufacturers are experts at taking these factors into consideration, but it is essential that you provide them with accurate information that includes worst case scenarios. Incorrect calculations can have costly consequences, endangering the integrity of the pallet structure and damaging the produce. Receivers of fresh produce are likely to charge for re-palletising, making incorrect calculations of carton strength very expensive.
Poorly designed cartons will cause major problems. Sagging cartons can obstruct ventilation across the cartons and is likely to cause mechanical damage to the produce in the carton below.
The airflow design is of utmost importance. You want to get the air in a well-structured manner towards the side of the pallet, only to get to the product and create chaos in an interflowing way inside the box so that the cooling air can do what it must do: Cool your product down in a uniform manner throughout the whole pallet load.
Boxes should be designed to allow for adequate air flow, which together with cooling requirements are produce-dependent. In general, a 6 to 8 % opening per side should be sufficient to get proper cooling. For example, insufficient air flow across cartons containing climacteric produce may result in local temperature increases and build-up of ethylene and or excessive condensation, resulting in bacterial growth and SO2 burn.
On the other hand, excess air flow can result in excess dehydration if the produce wasn’t handled correctly after harvest. That is also avoided with our applied postharvest philosophy. Remember that the use of plastic liners will alter air flow and a carton that is well designed with sufficient ventilation for non-bagged produce, is unsuitable for bagged produce. Bags will block vent holes in the base of the cartons, making them redundant.
It is important that the vents on adjacent cartons on the pallet are aligned. This solution enables unrestricted air flow across the pallets along both axes and optimum ventilation of both bagged and non-bagged produce. During the design phase, carton configuration on the pallet should be studied, as this can significantly affect air flow. Boxes should be designed so that outer carton walls are aligned with pallet base. This strengthens the pallet structure and will help prevent collapse.
Carton sides are flush with pallet edges. Obviously, the cooling method used after packing will influence the type of material used and the ventilation design.
Here’s a quick reminder:
For forced air cooling (FAC): wooden crates, corrugated cartons, waxed and non-waxed cartons where unobstructed air flow across the pallet is required.
Passive cooling in cold chambers: similar and ventilation design should take into consideration that incoming cool air is passively circulated within the chamber. Ventilation holes must be relatively large to allow respiration heat from the pallet centre to escape as quickly as possible.
Different modes of transportation (trucks, containers, reefer vessels) use different refrigeration methods, each with its own air flow schematic.
- In containers, which are not designed to cool down product but only to hold temperature, air flow comes from the floor T-Bars and flows upwards. If produce is packed in carton liners or plastic trays, ventilation holes on the base of the carton will be blocked and become redundant. In this case, the only option for ventilation is horizontal air flow and the box design will need to accommodate for this. But your pallet should be cooled, correctly to core temperature over the whole pallet on the land side cooling.
- In reefer vessels air flow is usually from the sides and bottom. Horizontal air flow must be extremely efficient to compensate when vertical air flow is blocked due to carton liners.
- Truck refrigeration typically flows from the top down and chilling injury to sensitive fruit on the top rows is a real risk. Excess dehydration of produce on the top layer is also likely. Good box design can help minimise or eliminate these problems. In addition, a layer of empty cartons is often placed on the top of the pallet to prevent intensive contact of cool air with chilling sensitive fruit and to reduce dehydration.
- Conclusion
Working closely with carton, punnet, and inner packaging manufacturers to design the best box combination for your needs can reap significant rewards. While carton/crate designers typically focus on price and graphic artwork, our insights about handling, cooling/refrigeration and ventilation will ensure that your new box serves you well, effectively protecting and preserving your perishable cargo.
And you will avoid serious produce quality problems due to simply badly designed cartons.
We have fine tuned our designs and have designed a fast and handy spreadsheet to calculate ventholes per your different boxes. Our designs for both 300 x 400 as well as 600 x 400 and various other designed box sizes can be used throughout the industry.
But remember, you will have to learn to start looking at the whole cake and not just at slices of it. Holistic problem solving. You can’t have your cake and eat it.
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.
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