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‘Thank you berry much, South Africa,’ say global markets

‘Thank you berry much, South Africa,’ say global markets

By John Ackermann

Blueberry and raspberry production has grown roughly tenfold in the past five years, spurred on by growing local consumption and massive growth in berry sales internationally. Industry leaders believe production will continue to increase for some years to come as global demand continues to surge.

Five years ago, South Africa exported only a few hundred tons of berries every year (about 200t in 2008), but production increased at such a rapid pace over the past five years that the industry now exports more than 1 000t of both blueberries and raspberries, and 50t of blackberries a year.

South Africa exports about 80% of all berries produced and the most important markets are the UK and continental Europe. South Africa has the advantage of counter-cyclical seasonality to northern hemisphere production. Southern hemisphere berries are in demand, particularly during the northern hemisphere winter when their local supply is limited.

“We are a small producer in international terms. Our main competitors in blueberries are South American countries such as Chile which produces about 17 000t of blueberries a year and Argentina which produces about 14 000t. But we can compete with these European countries because of our geographical proximity to the market.

“We also compete well in terms of quality. We don’t necessarily produce a better product, but we do produce a more consistent product, because we have a smaller number of producers, therefore making it easier to ensure that quality controls are in place throughout the industry,” says Trevor McKenzie, chairperson of the South African Berry Producers Association.

The total value of berry sales in the UK increased from around GBP170-million (about R2.2-billion) a year in 2001 to GBP668-million (about R8.6-billion) in 2010. Given the huge potential for growth in this sector, it should be no surprise then that the berry industry was singled out as one of the smaller, labour intensive industries with huge expansion and labour creation potential in the National Planning Commission’s development plan.

Unlike the other fruits such as apples, grapes, citrus and avocados that are consumed locally and exported in large volumes, berries are more delicate to handle and have a very short shelf life. When cooled within one or two hours after harvest and packed under optimum conditions, berries can have a shelf life of eight to 10 days. A relatively brief period to allow for distribution and getting the berry from farms, such as the Western Cape, to supermarket shelves in London and still have three or four days to be purchased by the consumer.

Consumer quality and shelf life is very much dependent on the handling and cooling rate of the freshly picked berry which arrives at the pack house at temperatures of between 20 and 30°C.
After picking in the growing tunnels, the berries are packed into punnets in the field, then transported to the pack house, sorted, weighed, packed into cartons, palletised and cooled to a core temperature of 1°C before being despatched in a refrigerated vehicle. Core temperatures throughout is essential for the berries to withstand the air travel, without refrigeration, to the European market and arrive with the best quality and longest shelf life.

Rapid growth in local and international demand, has taxed the infrastructure and cooling facilities of local berry producer, Haygrove, that has three sites in South Africa. The Eden site in George, being the largest, a smaller in Hermanus (Heaven) and the third in Volksrust (Amajuba).

In 2016, Coolcheck was commissioned to survey the sites to advice on extensions needed to handle higher volumes without any compromise in quality and the least disruption to production.

The Heaven site in the Hemel en Aarde area of Hermanus, was the first site to be modified ahead of the peak in the raspberry season. Raspberries are harvested from week 44 to week 26, with the highest volume in December, when ambient temperatures are at highest levels.

The ratio of surface area to mass of raspberries, is the highest of berries and has an impact on the cooling rate compared with the hardier blueberry, for example. Haygrove has eight different punnet sizes to cater to specific client requirements. Each punnet has 250g of berry and typically each pallet has 270 to 400kg of fruit. Clients also require the raspberry to be a distinct colour; some want the berry to be a dark red, others want it to be pink and others almost orange. The colour depends on the level of maturity and impacts on the heat of respiration, which the refrigeration plant must handle. All these factors are considered in estimating the cooling load, the air circulation volumes and humidity levels to handle higher volumes and to improve the quality of raspberry at the point of sale – be it London, Johannesburg or Cape Town.

Humidity levels at the pack line was a prime consideration. The dew point of the air must always be lower than the core temperature of the fruit to prevent any condensation on the fruit as this leads to mould forming and rejection by retailers.

power saving was a prime consideration in the redesign of the refrigeration system.

A further operational issue must be considered in the design. At the start of each day, the air temperature in the pack line must be maintained at between 2°C and 12°C depending on the pulp temperature of the incoming fruit (some fruit may have been held overnight at 2°C). Later in the day when the fruit arrives directly from the pickers, the air temperature is maintained at 12°C. The switch over of the air temperature controller between the two temperatures is done manually by pack house staff.

A new dual circuit coil in a purpose-built plenum, with a high capacity fan and fabric ducting, was installed to reduce supply air velocity which is key to ensure staff comfort at low air temperatures. The coil of the air handler has a glycol circuit (-5°C) and a water circuit for re-heating. Additional plate heat exchangers in the chiller heat the water for the air handling unit with compressor discharge gas. “The performance of the custom-made Dixell control system to maintain optimum humidity levels, air temperatures and cooling capacity of the chiller to handle an average of 800 tonnes of raspberries or 124 tonnes of blueberries, has exceeded all expectations since commissioning,” says Kevin Schlemmer of Coolcheck.

The new rack to handle the higher cooling load, has two Bitzer six cylinder semi-hermetics with a nominal capacity of 250kWR at -9°C/35°C. The chiller has two refrigeration circuits which feed a common buffer tank with glycol at -5°C.

After the packing line, the cartons are palletised in a newly revamped insulated area with two rapid batch coolers, each cooling four pallets of berries to 1°C in one hour. Humidity levels of 95% are maintained to maximise shelf life.

Two new Colcoil blower coils, each with two 0.65kW fan motors, are installed in the prepacking area. In the open receiving platform, evaporative coolers are also installed to start the cooling of the berries from the very outer perimeter of the pack house.

As a backup, the newly installed evaporative condenser has a buffer tank of makeup water and a standby pump. “Backup of the water supply to the evaporative condenser is essential. Any outage of water supply brings the entire packing operation to a standstill,” emphasises Schlemmer.

The chiller plant, manufactured by Phoenix Racks and the remainder of the refrigeration plant was installed by Ronald Giles and his team of DRS Air Conditioning, based in Paarl. The polystyrene panels were installed by Evercool.

Power saving was a prime consideration in the redesign of the refrigeration system. Both compressors are fitted with variable frequency drives and ebmPapst EC fan motors are fitted to all blower coils and on the Evapco evaporative condensers. “All these power saving features and accurate temperature control has paid dividends,” says Schlemmer.

He quantifies, “The existing plant, before any of our modifications, had a cooling capacity of 161kWR, with a power draw of 191 amps and batch cooled the berries in three to four hours. The new plant with a cooling capacity of 250kWR, has a current draw of 215 amps and batch cools the berries in one to two hours.”

Effectively this means an increase of at least 50% in production nominal capacity with an increase of only 10% in power usage. When the second phase of the modifications are done, the increase in production and with a better quality product because of a more effective chill chain, will be greater.

Project team

Haygrove extends a sincere word of thanks to the project team, especially for their commitment during December when many role players were about to close for the summer vacation.
They include:

  • Surveying site: Coolcheck
  • Chillers: Phoenix Racks
  • Compressors: Bitzer
  • Cooling coils: Colcoil
  • Fans: ebmPapst
  • Customised control system: Dixell
  • Insulated panelling and doors: Evercool
  • Insulation of piping and glycol tank: DRS Airconditioning
  • Fabric ducting: Fabric Air
  • Evaporative condensers: Evapco
  • Haygrove representative: Susan Collins (George)
  • Refrigeration contractor: DRS Air Conditioning

*All images: John Ackermann

Click below to read the May/June 2017 issue of Cold Link Africa

CLA May-June 2017

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