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Macadamia processing

The challenge
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To reduce shell moisture content of recently harvested macadamia nuts, for the recovery of perfect and undamaged kernels.

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The solution
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With outer shell moisture reduced from 25% slowly and efficiently, sufficient kernel shrinkage will permit removal without kernel damage.

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Smarter processing to maximise quality
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"drying rate and final moisture content of the nuts is of utmost importance to the quality of the kernels"

 

"the development of a good roasted flavour and prevention of off-flavours are very important aspects of macadamia processing. Too high moisture contents, storage temperatures or storage periods can result in the development of staleness or rancidity. Roasted colour is closely related to flavour and is related to cooking time and temperature" - macadamia nut processing (Weinert)

 

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Shell drying of macadamias

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Attaining the finest kernel quality in macadamias is dependent on the interaction of a number of drying conditions: relative humidity, temperature, air speed and ambient conditions.  Of those, drying airflow is amongst the most critical.

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When macadamias are initially harvested, moisture contents can be as high as 25-30%, with 22-25% typical in Australia.  Without drying, such high levels of moisture content can rapidly lead to spoilage:fungal, bacterial, browning and in reduced shelf life.  It's therefore imperative to start drying nut in shell as soon as is possible.

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SVPro solutions are based on solar collectors that dehumidify and warm ambient air, which can then be driven through the harvested produce to gently and effectively dry.  The lower the rate of relative humidity, the quicker the drying; SVPro solutions regularly achieve <10% relative humidity in dry and sunny conditions.  As the macadamia nuts dry and their relative humidity decreases, so too much the incoming air remain at lower relative humidity to continue the process.

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Integrated with humidity sensors and controllers, SVPro solutions can be designed to deliver drying and dehumidified air only when required, at controlled air volumes. 

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Fan arrays for providing drying aeration are specified according to the method of storage.  Stored in silos, strong drying is usually required within the first 24 hours to remove any transpiration and water collected during harvest.  Thereafter fans are generally required to run at lower speeds to provide gentle aeration drying.

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The specification of fans, ducting, configuration and siting of SVPro solutions is tailored to each situation.  Storage conditions, particularly when stored in silos, will govern fan design; the storage depth, initial moisture levels, back pressures and local climactic conditions all play a part.  

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Modular and sized to suit processing volumes, SVPro solutions with integrated control systems available now.  And with academic research identifying the link between kernel dryness by airdrying and roasting colour, flavour and quality, can you afford not to manage harvest processing without SVPro? 

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