New table grape packhouse takes cold chain seriously

By Ilana Koegelenberg

Modderdrift Boerdery has its headquarters at Brandwacht Farm near Worcester in the Western Cape and is a producer,  packer and exporter of top-quality table grapes.

Modderdrift is the name of the original farm, which is just over 100ha in size. In 2015 the business expanded to include two additional units, Brandwacht and La Montagne, both located at Brandwacht, 30km to the southwest in the Breede River Valley. Initially these farms had approximately 60ha of vineyards, but in the near future the Brandwacht vineyards will also be expanded to around 120ha which will expand the total hectares under vine to over 220ha.

The farms and packhouses have well-developed operational infrastructure, including state-of-the-art packing, sorting and cold-storage facilities. The development of the production methods and post-harvest infrastructure to the best industry standards added value to the product and the market is provided with only the best quality.

All images by Ilana Koegelenberg

A new state-of-the-art table grape packhouse in Modderdrift was designed by Jan Neethling of JA Verkoeling. The project started in May 2018 and was completed in record time by the first week of December 2018, ready to pack in time for the new season. They previously had a smaller store, but the need arose for a bigger, more secure facility.

So, a new 55m x 20m packhouse with mechanical cooling was built. Packing generally happens from December until Easter weekend for this farm specifically.

Pre-cooler

When arriving from the vineyard, the grapes (in pallets) are off-loaded into the airlock with the door closed. The trucks will then pick up empty crates and return to the vineyard.

The grapes stand here for about an hour and could have an internal temperature as high as 30-35°C. This depends when the grapes were picked as the morning grapes are obviously much cooler.

Here, depending on what time of the day the grapes were picked, their temperature must be maintained or brought down before being packed. It’s important that the temperature of the grapes do not increase once they reach the packhouse.
If the grapes are colder than 18°C, they must be kept in the vineyard until the pulp temperature increases. Otherwise, if the temperature is below the dew point when it comes in, this will lead to condensation. That’s also why it’s important that the pre-cooler doesn’t get too cold – to avoid condensation. Also, if it has rained, the grapes can only be picked three days later to avoid potential rotting.

From the airlock, the pallets are pulled into the pre-cooler with trolley jacks. No forklifts are allowed in the packing facility to avoid any possible damage. Here, the grapes are cooled to about 20°C which can be done in 20 minutes, depending on the internal pulp temperature. The pre-cooler runs at about 20°C with up to 90% humidity. The incoming water temperature is kept at 12°C. The pre-cooler is kitted out with four evaporators of 38kW each.

Packing process

After the desired temperature is achieved in the pre-cooler, the grapes are lifted onto a conveyor belt and moved into the packhouse.


Here, as many as 350 women will process and pack the grapes when working at full capacity. Although there are men working in the pre-cooler side, the cutting out and packing is all done by women. The palletising is done by men. There are 102 stations which can pack a total of 112 pallets a day, or 20 000 boxes of 4.5kg. There is demand for 600 000 boxes per season.

Each woman pulls a crate and cuts out the bad or marked grapes before putting the rest in a box. Quality control is quite stringent and for every five packing tables, there is someone inspecting quality and checking that the cutting out was done correctly.

There is a monorail that moves throughout the packhouse to allow them to pack different weights and sizes. This can be set and adjusted as required.

Each packer earns a daily wage as well as a bonus for production. Each box gets weighed afterwards before being palletised. This prevents some people packing slower than others for the same pay. All the scales are linked to a computer and monitored. There are TVs throughout the packing store with an almost leader board situation to show who has packed the most. This helps motivate the staff to keep up and reach their targets.

Everything is carefully monitored. Even if there is something wrong with a box when it arrives overseas, they can trace back who packed that box. This was a new system they implemented a few years back and has been a game changer for quality control.

Perishable Products Export Control Board (PPECB) inspectors come through the store about three times a day to inspect product as well. They must put their sticker on every batch and make sure that the quality is up to scratch.
About 60% of the product goes out in punnets. This is easier to manage and offers more protection for the product. Once packed, the pallets are pulled to force coolers to cool the grapes down to 0oC in 12 hours.

Cooling requirements

In the packing store itself, the humidity must be controlled or else the boxes would get damp and lose their integrity if the humidity is too high. As such, the humidity in the packing store is kept at about 60 to 68 %. To achieve this, the incoming water temperature on the cooling system is 7°C.

Just for the packing store alone, 154kW of cooling is required. This is mostly made up of 8kW evaporators and a 22kW one for the fresh air supply – built locally by Colcoil. “You must allow for 8ℓ of fresh air per person per second in your design,” explains Neethling.

“Sometimes packing stores don’t have any fresh air supply, despite the obvious importance of this inclusion in the design,” says Neethling. “Otherwise the humidity increases too much inside, causing unfavourable working conditions.”
The packhouse was designed for maintaining 20° C inside, but it is often turned down to 18°C even. The client was very happy with the end-result and says sometimes it could even feel like it’s too cold inside.

To achieve the desired temperatures and humidity, two Midea chillers are located outside of the packhouse. The 130kW and 200kW chiller provide a total cooling capacity of 330kW. Both chillers run on R410a refrigerant. To ensure the temperature inside the packhouse is maintained, insulated panels from Specialised Panel Manufacturing (SPM) were used.

Temperature matters

“It’s been proven that the quicker grapes reach under 4°C, the longer your shelf life,” explains Neethling. “It’s all about the respiration on the grapes. Otherwise you run the risk of dry stem, which can drastically bring down the price of your product, cutting into profit margins.”

Grapes can have a shelf life of as long as 8 to 12 weeks if the cold chain is properly maintained. It’s key to achieve the longest possible shelf life for export table grapes as it usually takes about a month just to reach its destination.
A problem that persists everywhere is that the attics are too hot. Cooling them down is difficult and it is expensive to put up panels, explains Neethling who once measured temperatures above 60°C in a pack store attic. There is a hot water tank as well as a cold-water tank on site for circulating the water through the chillers. Four evaporative coolers are also used to help cool the attic.

Click here to read the issue of Cold Link Africa

 

 


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