Macadamias are a hard nut to crack, but that’s not the only step in the production of macadamia kernel.
The process starts on farm with growers harvesting the nuts, removing the fibrous outer husk and visually inspecting the nuts and removing any that are obviously defective. The nuts are then stored in a silo until a grower has a sufficient quantity ready to dispatch to MPC.
The nuts are received at MPC in a range of ways – from 400kg bins right up to B double loads of 35 tonnes. The weight delivered by a grower is recorded and samples are taken that are used to assess the mositure content and the quality of the nuts delivered. This information is used to determine how much a grower is paid for their consignment.
After sampling, the nuts are transferred via series of conveyors to a state of the art drying facility. This brand new drying facility utilises the latest in energy saving technology. The heat used for drying comes from the burning of macadamia shell – a by-product in the processing operation. The drying facility uses a recirculation system and when the air is too wet for drying, special fans exhaust this wet air from the building. At the same time, new drier air is brought into the drying facility from a specially designed roof area that is pre-heated by the sun.
The drying system is not only good for macadamia kernel quality but also the environment. By burning macadamia shell for drying, a renewable fuel source, MPC has been able to reduce its carbon emissions for drying by 99.6%
To avoid damage to the nuts when filling the large drying bins, a specially designed easy let down system is used. All of the drying steps are controlled by a computer system, allowing precise regulation of the temperature and humidity of the drying system.
After drying, the nuts are cracked. A purpose built machine breaks open the hard macadamia shell, revealing the creamy white kernel inside. A series of processes are used to separate the shell from the kernel – such as sizing graders, air separators (called aspirators) and electronic colour sorters. At the end of the process, macadamia kernel free from shell is then sent for manual inspection.
The first stage of sorting utilises state of the art electronic colour sorters. The machine is programmed to remove unsound kernel and/or shell by measuring colour intensities. These machines are fast! The colour sorter works like this:
During machine set-up, trained operators take pictures of good and bad kernels using the 2 cameras in the machine (one top and one bottom). The operator then uses the inbuilt software to identify the colour of the defect and the size of the colour area the defect covers. Each pixel is 0.1mm2 and the sorters can differentiate 16 million colours!
In operation, the macadamia kernel passes between the cameras where it is photographed, the computer scans the image of each kernel checking for bad colours and the area that the bad colour covers – with defective kernels being rejected by firing a short sharp burst of compressed air, which deflects the product into the reject stream. All of this happens in 4.3 milliseconds!
The kernel that passes through the colour sorter goes to the sorting area for manual inspection. The product that the colour sorter rejects is collected under the colour sorter and is further processed to recover saleable kernel. Reject kernel is not wasted – it is sent off and used for macadamia oil production.
The manual inspection area is where specially trained sorting staff inspect the kernel a final time to remove any defects missed at the other steps. From here the kernel moves to a sizing tower – this is where the kernel is separated into its different sizes (better known as styles) – these being whole kernels, halves and pieces.
Once sorted and sized, the kernel is tested to ensure it meets the highest standards. If the kernel does not meet the standard, it is resorted. Kernel that passes the rigorous testing process proceeds to pasteurisation where it is treated to ensure food safety. The pasteurisation process has been validated to provide 5 log reduction of food pathogens like Salmonella. After pasteurisation the kernel is packaged. Here a special machine dispenses an exact amount of kernel into cartons. The cartons are checked for weight and proceed along a conveyor system, where they have two identifying barcode labels attached – these labels identify the product and provide full traceability back to the farm.
All finished product is packed in vacuum sealed-nitrogen flushed foil pouches within cardboard cartons – this ensures the kernel stays as fresh as the day it was produced. From packing the cartons are stored in a warehouse – that operates at approximately 12 degrees celcius. A cool temperature is used to ensure the freshness of the kernel is maintained. From the warehouse kernel is dispatched to customers – both locally and all over the world, to make the finest macadamia products possible.