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South African cooperative business Golden Macadamias has invested in a TOMRA 5C sorting machine with Biometric Signature Identification technology, in the anticipation of the need to produce macadamias in even greater quantities while ensuring perfect quality

TOMRATOMRA's unique BSI+ technology scans materials with both near-infrared and visible spectrum wavelengths. (Image source: TOMRA Food)

TOMRA Food designs and manufactures sensor-based sorting machines and integrated post-harvest solutions for the food industry.

Golden Macadamias has been able to meet the stringent quality requirements of export markets to tap into the booming international demand for macadamias. Attaining the highest product quality with large production volumes has been made possible by investing in the best available technologies. The most recent example of this is Golden Macadamias' acquisition of the new TOMRA 5C premium optical sorting machine, explicitly developed for nut and dried fruit applications. When this machine is combined with TOMRA's unique Biometric Signature Identification (BSI) scanning technology, it can detect and eject product defects that no other technology can see. 

The South African macadamia industry contributes roughly 20-25% of the world's macadamias, expressed as NIS volume (INC). South Africa is the largest contributor, with other significant contributors like Australia, Kenya, and China.

Norman Smith, area sales manager Africa, TOMRA Food, said, “Today 98% of the macadamia crop is exported. Approximately 55% of South Africa's macadamias are sold to the kernel market, mostly for export to the USA, Europe, and Asia. The other 45% goes to the in-shell market, some for sale domestically but mostly for export to China, where consumers prefer to crack the shells themselves. It is the kernel market which demands the greatest product quality."

A mix of manual and automated sorting

Some macadamia sorting is still done the traditional way, by hand. In addition to grading being done manually, nuts are put into a water bath early in the production process, where only the unwanted immature and underdeveloped nuts float to the surface and can be manually removed. But human sorters are unavoidably subjective and more vulnerable to error. Manual sorting can also diminish product quality because handling kernels makes them oilier. 

To minimise these drawbacks, Golden Macadamias complements the sorting tasks that have to be done manually with sorting wherever possible by machines and has employed TOMRA's BSI technology after the nuts are cracked and before they are manually graded. 

The TOMRA 3C eliminates foreign materials, including stones, shells, and sticks, and, depending on the sorting process, can achieve an incredible efficiency of up to 99.5% purity. It is also well-suited to separating shell from kernel with a low giveaway. The machine can do all this while sorting more than 20 tonnes of nuts per hour. The TOMRA 3C can also be used in a second position on the line to remove major discolorations, rotten and moldy kernel, and any remaining shell

Smith added, "To examine nuts not only externally but also internally, TOMRA's unique BSI+ technology scans materials with both near-infrared (NIR) and visible spectrum wavelengths. This instantly compares the biometric characteristics of objects to features stored in its database to determine whether they should be accepted or rejected. This technology has the ability to detect and reject hard-to-see and nearly invisible defects. In macadamias, such defects include early germination; mould; immature and shrivelled nuts; cracked, pale, and dark or black shells; the ‘791 spot' kernel disorder; and insect damage from stink bugs, nut borer moths, and false codling moths.” 

Future-proofing with rapid return on investment

Peter Edmondson, general manager at Golden Macadamias, said, “We currently work two eight-hour shifts five days per week throughout the whole six- to eight-month production season, and our production volumes are continually increasing. TOMRA's machines handle this pressure well, and we have been very impressed by the results delivered by BSI+ technology. After cracking and before manual grading, we have been able to halve the level of unsound nuts from 8% to just 4%. No other technology can match this.”