Bring bruising under control

A joint venture between Hortgro and Dutoit Agri aims to reduce losses of exportable apples due to bruising. By Anna Mouton.

“We produce 70% export-quality fruit off the tree, but we struggle to get 50% into an export carton,” says Willie Kotze, technical adviser at Dutoit Agri. “We know why we lose those fruit — the two biggest defects are bruises and injuries.”

Kotze has been working with consultant Henco Smit of Prima Defensio to figure out where bruising happens in the journey from picker to pack house. Last season, they placed loggers in bins to measure and record the forces acting on the fruit. Excessive forces — usually impacts or vibrations — rupture fruit cells and lead to bruising.

Even though they only have data from a few loggers, Dutoit Agri has already made some gains against bruising. Now, they are partnering with Hortgro to expand the project to benefit the wider industry.

Bin-trailer impacts

One lesson from last season’s data is that pickers are disproportionately blamed for bruises. Kotze cites an example where their quality controllers consistently found that about 13% of the apples picked by a specific team were bruised. He went to the orchard unannounced and had the team leave a couple of full bins untouched overnight.

“No one but the pickers had handled those fruit,” recalls Kotze. “The next day, we examined all those fruit in the orchard — the bruises were 2%–4% per bin.”

Loggers in the bins showed that forklifts are responsible for much of the damage. However, Kotze is determined to minimise all causes of bruising, including impacts while the fruit is transported on bin trailers. He notes that loggers inside bins are not ideal for tracking impacts because retrieving them involves unpacking the entire bin.

This season, he is trialling loggers attached to the outside of bin trailers and studying the relationship between forces measured outside and bruising happening inside the bin. Kotze would eventually like automated alerts when the fruit experiences potentially damaging impacts.

“Our initial data showed about 213 significant impacts per kilometre with normal bin trailers, compared with 80 for the normal bin-on-the-ground system and 20 for the bin-on-the-ground with air suspension,” he says. “It’s a massive shift.”

Kotze’s conclusions are preliminary because he only had a few loggers last season. The collaboration with Hortgro expands his monitoring capacity to 60 bin-trailer units representing the different systems so that he can quantify their contribution to bruising.

Bumps in the road

Last season’s data also highlighted road transport as a source of damaging impacts. Dutoit Agri was already restricting the speed of their trucks, but the loggers proved that further reductions were necessary on specific stretches of road.

“We measured six or seven big impacts on an average load of fruit coming from our Tandfontein farm [in the upper Koue Bokkeveld],” says Kotze. “That’s with air cushions and a driver that reckons he’s being careful.”

Measuring the forces acting on the fruit allowed him to map the principal routes along which fruit are transported in the Ceres region. This season, Dutoit Agri will do the same in the Langkloof. Drivers can then be issued with detailed instructions on safe speeds for different sections.

“You have to do this for every road, but fortunately, there aren’t that many,” says Kotze. He suggests that pack houses could work with growers to identify and map the main routes for each region.

Individual growers can also use loggers to determine appropriate speeds for dirt roads in different conditions. “You quickly get an idea of the sort of dirt road where you need to stick to 20 kilometres per hour when transporting fruit,” comments Kotze.

Dutoit Agri is also lining bins with a commercial shock-absorbing product developed by Smit. “It’s something you can buy off the shelf to help you when you have bad roads, especially with sensitive cultivars,” explains Kotze. “Having liners will always be better than not having them, especially when you don’t have eyes behind your head to check all the drivers handling your fruit.”

Fail-safe forklifts

Kotze and Smit previously found that forklifts — on the farm and at the pack house —caused many bruising impacts on fruit. Damage can happen whenever bins accelerate or decelerate too quickly.

“We have a logger that we attach to forklifts to measure the forces on the fruit,” says Kotze. “Forklifts on farms are rented, so you can’t equip them with expensive telemetry, but these simple loggers are affordable and can indicate what’s happening to your fruit.”

Pack houses lease forklifts long-term, so Dutoit Agri is fitting theirs with telemetry to collect and transmit data linked to operator performance. The speed of the forklifts and the acceleration of the mast can also be constrained. In addition, Dutoit Agri has ordered vibration dampers for all their pack-house forklifts.

“Vibration dampers are hydraulic systems that act almost like shock absorbers on the forks,” explains Kotze. “We tested them using the loggers. When we looked at the data, it was a no-brainer.”

This season, Kotze is expanding the monitoring of forklifts in collaboration with Hortgro. He hopes to develop standards for forklift operation so that pack houses can improve their handling practices. “There can’t be less focus on correct handling when bins arrive at the pack house,” he says. “Every single bin must be handled within spec.”

Kotze hopes working with Hortgro will allow him to generate the data needed to inform handling practices from picker to pack house. He wants to create guidelines so anyone can use a logger correctly to audit and improve their processes.

“We want to give people a tool with which they can quickly make a big difference,” he says. “We know the pickers bruise the fruit, but we’ve now seen that it’s not only the pickers.”

Kotze is also willing to share the lessons Dutoit Agri has learned, such as those mentioned in this article. “We have these high-tech orchards. We’re using shade nets and reflective mulch,” he concludes. “But now we must protect the fruit we produce because we have to export it.”