Traditionally, extraction of the kernel from the shell of the cashew nut has been a manual operation. The nut is roasted which makes the shell brittle and loosens the kernel from the inside of the shell. By soaking the nuts in water, the moisture content of the kernel is raised, reducing the risk of it being scorched during roasting and making it more flexible so it is less likely to crack. The CNSL is released when the nuts are roasted. Its value makes collection in sufficient quantities economically advantageous.
However, for very small-scale processors, this stage is unlikely to take place due to the high cost of the special roasting equipment required for the CNSL collection (see the section on ‘hot oil’ roasting). If the nuts are being manually shelled, gloves need to be used or alternatively, the nuts should be tumbled in sawdust or ashes to absorb the liquid coating which has a harmful affect on the skin.
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The shell can be cracked either manually, using a hammer, or mechanically. Manually operated blade openers (as listed in the supplier’s section) are relatively inexpensive, however the more successful mechanical methods depend on the nuts having passed through the ‘hot oil’ CNSL extraction operation.
Care must be taken not to break or split the kernel at this or subsequent stages as whole kernels are more valuable than broken ones. Once the kernel is removed from the shell, it is dried, the testa is peeled off and the kernel is graded.