Cashew Nut Processing: From Steam Cooking to Packaging
Step 1 : Steam Cooking
Purpose: To expand and harden the shell of raw cashew nuts, making them easier to shell.
Process: Raw cashews are steamed in a cooker vessel until the shell absorbs steam and becomes firm.
Factors: Duration depends on cashew condition and atmospheric conditions.
Cooling: After steam cooking, the cashew nuts are air-cured (cooled) overnight by spreading them on the floor in a shaded area.
Benefits: This process helps remove excess surface oil from the shell, allowing easier shelling. It also ensures the shell hardens enough for effective shelling, protecting the cashew kernel inside.
Step 2 : Air-Curing:
Purpose: To cool and dry the steamed cashews.
Process: Cashews are spread out in the shade to cool overnight.
Step 3 : Cashew Nut Shelling Machine
After steam cooking and air cooling, the cashew nuts are moved to storage silos, where they are prepared for shelling. Both manual and mechanized shelling machines are available, with various operational systems.
Key Features of Shelling Machines:
Mechanized System: These machines are configured for continuous operation, separating the shell from the kernel and mechanically scooping the kernels into an automated system.
Output Capacity: Manual shelling machines have output capacities ranging from 25 kg/hr to 450 kg/hr, while fully automated lines can process between 300 kg/hr to 1200 kg/hr.
Shell Separation Process:
Shelling Output: The shelled nuts are passed through a perforated vibratory deck, which separates the kernels from the shells. A pneumatic aspirator sucks out the lightweight shells for further processing or disposal.
Use of Cashew Shells: The discarded shells are used to extract cashew nut shell liquid (CNSL), a valuable byproduct used in the polymer industry. Shell cakes are also used as burning fuel.