Advanced processing of almonds (AL12003)

What was it all about?

Beginning in 2013 and ending in late 2018, this project supported… 

• Research into effective aeration and dehydration of bulk almonds in silos, bunkers and sheds
  
  
• Research into the effective hulling of almonds in-field and during processing, as well as the improved cracking of almonds
  
  
• Work into technologies to sense temperatures of almonds and their waste in stockpiles; to yield map almond pick-up in the orchards; to compare methods of storing bulk almonds; and to develop almond hulling, cracking and cleaning equipment.

The project team noted that there are many factors that can lead to quality downgrades in almonds, such as pests and weather damage (rain = staining; hot and humid = concealed damage; hot and dry = skin flaking and split cotyledons; humid = mould). For these reasons, the researchers recommended looking at harvesting the fruit after hull split but before it is fully dry, so it can come out of the elements.

Their related research shows that early harvest and dehydration preserves the micro-nutrients in the almond kernels at their maximum status. It also found that the hulls are easier to remove from the shells before they are fully dried. The researchers noted that this indicates a move toward shake and catch harvest systems for almonds – which doesn’t decrease yields nor quality – has many advantages when combined with in-field hulling and hull separation.

With a patent pending, equipment was subsequently developed that can undertake the hulling and separation of detached hulls in the field on mobile equipment, and at storage facilities and factories. The researchers noted that if only in-shell almonds are brought in from the orchards, the volume of almonds can be halved – thus reducing both transport and storage costs – and the nutrients that are in the hulls will remain in the orchard.

Other work in the investment included…

• Work towards a retro-fittable yield mapping system for almond harvesters, based on lasers, to provide growers with a map of their almond harvest yields. The data collected from such a system could be used for future orchard management, though further development is required on this technology.
  
  
• Research and trials that have shown that temperature and humidity sensors placed into an almond stockpile can provide accurate in-situ measures of kernel moisture content – whether the almonds are in-hull, in-shell or kernel forms. This relies on the almonds being at their equilibrium condition and a calibration being formed between moisture content and relative humidity/temperature readings. The system was used effectively with on-farm stockpiles before dispatch to a processor, whilst in transit to give an automated moisture reading upon arrival at the receival weighbridge, in silos as the almonds moved past the sensors to go into the processing line, and in finished product whilst it was stored in a warehouse.

• Looking at controlled aeration conditions to precisely control kernel moisture content, using a combination of an evaporative air conditioner and a heater to regulate the air going into bulk almonds to the desired equilibrium moisture content. The project concluded that there are three critical times for moisture content to be controlled and altered:
  
  
  • For long term storage, kernels should be held at a four per cent kernel moisture content to protect the micro-nutrients from degradation.
    
    
  • For processing of the almonds to take the kernels out of the shell without any kernel damage, the kernel moisture content should be around seven to 10 per cent and multiple impacts used, as per the patent pending technology from the project. Using the existing rolls-over-belt technology there is another ideal moisture content of between five to 5.5 per cent to minimise kernel damage to approximately 20 to 30 per cent chipped and scratched.
    
    
  • For the consumer that likes the crunch of an almond, its moisture content should be in the range of five to 5.5 per cent.