FOOD g As with many imaging techniques a lot

depends on lighting. Firstly, the systems require very flat illumination profiles. Brightness has to be homogeneous to minimise the amount of variability in the image, and the angle of light has to be the same to remove any shadowing, Kelf said. Te light has to be tailored to the right

application, whether that’s using colour or white LEDs, or UV LEDs for fluorescence imaging. It is then a matter of trying to balance

all these things, while keeping the light source in a sensible footprint, and also making it hygienic. Tere are constraints on temperature emitted by lights, and not having areas where dirt can accumulate. In addition, the machines can run 24 hours a day. ‘You need to have as much efficiency as you can in terms of uptime, while making sure the customer gets the most benefit from these systems,’ Kelf said. In the last few years Bühler has launched its Xenon lighting solution to boost the lifetime of incandescent illumination and reduce machine downtime. Bühler uses two overarching lighting

solutions: either many low-power white LEDs, or a small number of high-spectral purity LEDs. Spectral purity is less important when using many white LEDs, as they’ll all marry together, Kelf said. ‘At the high end, certainly for sorting rice, then you’d want to use a small number of LEDs with

high spectral purity,’ he added. Rice sorting involves identifying very subtle yellow or grey grains, which requires exact colour imaging. Bühler has just released its Sortex S

CrystalVision system for sorting rice, which can remove colour defects and foreign materials, including glass, at 18 tonnes per hour. ‘To spot glass in rice comes down to knowing the illumination properties and what to look for in the image,’ Kelf said.

Food security Maize production is concentrated in four countries: USA, China, Brazil and Argentina, which grow more than two thirds of the world’s maize. In a study published in 2018 in PNAS (115 (26) 6644-6649), the authors projected that mean total production of maize would decline by 18 per cent in the United States with 2°C of global warming. Wheat yields are also expected to decrease by six per cent for every 1°C global temperature rise, Dr Ian Roberts, CTO of Bühler, said during a virtual press conference the firm held to mark what would have been the Interpack trade fair. Bühler has pledged to reduce waste,

energy, and water in its customers’ value chains by 50 per cent, and is rolling out new technology and processes to help meet this target by 2025. ‘Estimates suggest one third of all food

What to make of a round swede

Imaging firm Scorpion Vision is making sure supermarket shelves are stocked with well-trimmed swedes and leeks, while at the same time reducing food waste in the supply chain. The company’s Jana

Lambrecht described two installations that were up and running as part of UKIVA’s technology hub, the virtual version of the association’s machine vision conference. All the presentations in the hub remain live and free to view. Both systems use stereovision to guide a knife – mechanical or water jet – to trim the top and bottom of swedes and leeks at a rate of one vegetable per second. The swede trimming system

uses two area scan colour cameras imaging in white light. The stereovision set-up gives

a height map and contour of each swede. From this, the system finds the centre of the swede and then scans across its length in 5mm increments, making a width measurement at each stage. Once the width falls below a certain threshold the information is sent to a control unit to tell the system where to position the cuts. Lambrecht said that the

only problem the system encountered was when the swede was close to being perfectly round, because it’s then difficult to pinpoint an exact place to make the cut. Leeks are trimmed with a

water jet, cutting away leaves at the top, as well as the roots. The leeks are presented individually to the camera system in single pockets. The system uses three methods to determine a cut position, the


best one of which is decided according to confidence values. One method is to use the difference in light intensities between the leek body and the root – the body is bright while the root is darker – and set thresholds for where to place the cut. There is also a 3D model, as well as a contour model of the leek, from which the indent between body and root can be seen. The leek trimming system had to contend with steam from the water jet misting up the camera housing, as well as stray leaves obscuring the image. Paul Wilson, managing

director of Scorpion Vision, told Imaging and Machine Vision Europe: ‘We primarily use stereovision as it gives us the opportunity to look at something in 2D as well as in

3D, and there are advantages to using both image sets. ‘In terms of productivity

gains, we aim to achieve 100 per cent image analyses with a valid output,’ he continued. ‘Of course, sometimes a product may not be properly presented for the cutting device, but nevertheless we will still attempt to make a sensible decision based on what the vision system sees. Quite often the limitation with these machines is the freedom of movement of the cutter if it is driven by servos – which is why the use of a robot can be better, as it can offer six degrees of freedom, which is of course the benefit of a true 3D vision system.’ By automating the process

of trimming vegetables, such systems can reduce waste by making precise cuts, and also

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grown on the planet is lost,’ Dr Matthias Graeber, head of data science at Bühler, told Imaging and Machine Vision Europe. ‘At the same time, one third of all energy goes into food production. Tat means around 10 per cent of all energy is lost – a clear opportunity to act. We really try to minimise losses, and often that goes together with financial savings for our customers. It is good for our customers, but it’s also good for the environment – if we maximise the yield of flour that can be produced from one tonne

‘Tis can turn a harvest from being unfit for human consumption to one that is safe to eat’

of wheat, we’re more efficient with the raw material. Any small improvement we can achieve can have a massive effect globally.’ Bühler is also working with Microsoft

to develop its LumoVision optical sorting machine, designed to spot maize contaminated with aflatoxin from fungal mould. Aflatoxin is a carcinogenic mycotoxin that causes 155,000 cases of liver cancer per year in developing countries, and contributes to stunting the growth of millions of children. Te toxin is not destroyed by heat, so cooking doesn’t make it safe, and


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