Cashew processing
Manufacturing of cashews is a complex process. Below is a flow of cashew processing followed by Jayalaxmi Enterprises. With the advent of technology the cashew processing which was manual is in the process of being mechanized and likely to be successful in coming years. There is continuous up gradation of latest changes in our processing.
Roasting: The application of heat to the nut releases the nut shell liquid and makes the shell brittle which facilitates the extraction of the kernel when breaking the shell open. Three methods of roasting exist: open pan, drum roasting and the 'hot oil' method.
Shelling: The objective of shelling is to produce clean, whole kernels free of cracks. Traditionally in India, this operation was always done manually. Other countries had difficulty in competing with the great skill and the low wages of the Indian workers. Therefore, India had enjoyed a virtual monopoly of cashew processing for a long time. Technological advancement has led to mechanization of shelling in present cashew processing . Manual shelling is still relevant to the small scale processor, although a close look at the mechanical option is advisable in all cases.
Separation: After shelling, shell pieces and kernels are separated and the unshelled nuts are returned to the shelling operation. Usually blowers and shakers are used to separate the lighter shell pieces from the kernels. The greatest problem is to recover small pieces of kernel sticking to the shell. This is usually done manually from a conveyor belt used to carry all the sorted semi shelled nuts.
Drying: The shelled kernel is covered with the testa and to facilitate removal, i.e. to peel in order to produce the blanched kernel, the shelled kernel is dried. This also protects the kernel from pest and fungus attack at this vulnerable stage. The moisture content is approximately 6% before drying and 3% after. Drying usually takes six hours, at a temperature of around 70 ° C. A uniform temperature throughout the drier is essential to avoid under drying or scorching. It is in the dried condition the kernels are most vulnerable, being both brittle and susceptible to insect infestation. Therefore, at this stage, they must be handled with care and moved to the next stage of peeling as quickly as possible
Peeling: At this stage, the testa is loosely attached to the kernel, although a small amount of kernels may have already lost the testa during the previous operations. Manual peeling is done by gentle rubbing with the fingers. Those parts still attached to the kernel are removed by the use of a bamboo knife. One person can peel about 10-12kg of kernels per day. The mechanized processes of peeling differ widely. They include air-blasting, suction, a freezing operation and a system of rubber rollers. The operation has a low efficiency due to the difficulty of removing the testa and the amount of breakages can be as high as 30%. Currently research and development is taking place to improve the viability of the mechanization of this operation.
Grading: The grading operation is important as it is the last opportunity for quality control on the kernels. With the exception of a few grading aids, all grading is done by hand. Power driven rotary sieves are one mechanical method, another being two outwardly rotating rubber rollers aligned at a diverging angle. For large operations looking towards export markets, it is necessary to grade the kernels to an international level.
Rehumidification: Before the kernels are packed it is necessary to ensure that their moisture content rises from 3% up to around 5%. This is to make the kernels less fragile, thus lessening the risk of breakage during transport. In humid climates, the kernels may absorb enough moisture during peeling and grading to make a further rehumidification process unnecessary.
Packing: The normal packaging for export of kernels is in air-tight tins of 25lbs in weight. The packing needs to be impermeable as cashew kernels are subject to rancidity and go stale very quickly. After filling and weighing, the cap should be soldered on in preparation for the ‘vita pack’ process. This consists of removing all air from the tin and substituting this with carbon dioxide (CO2). Some large-scale machines will operate on six tins at a time, creating a vacuum in each and then filling with carbon dioxide. Some processors do not have vacuum pumps and displace the air in the tin by feeding in carbon dioxide through a small hole in the bottom of a side of the tin. The carbon dioxide valve is turned off when all the air has been replaced. The holes in the tin are then sealed, with the hole at the bottom of the side of the tin being done first, and the one on the top last.
