How Are Cashews Processed Commercially?

A worker processing cashews in a factory

Cashew processing is a procedure that begins after the harvesting, when cashews are collected from the tree, and ends with them being packaged. A lot of hard work goes into this process, but it’s definitely worth it for all the delicious cashews we get to enjoy!

This blog post will examine the hard work that goes into processing cashews.

CNSL and the Danger of Processing Cashews

Before diving into the steps, you must know that cashew processing is a carefully controlled procedure (in most places) for a particular reason. While cashews are not toxic, the shell that houses the cashew contains CNSL, or cashew nut shell liquid. CNSL contains urushiol, a highly irritant toxin that can cause severe reactions, such as burning, blisters, itching, and rashes, when it comes into contact with the skin.

The poison ivy, which most people are familiar with, is actually connected to urushiol. Fortunately, the careful processing used when processing cashews means that it’s improbable that a person accidentally consumes cashews contaminated with urushiol.

CNSL changes the cashew processing methods

Before, I mentioned that it’s important for you to know about CNSL because the first steps of processing cashews are done with this allergic toxin in mind. In other words, cashews are not processed like other nuts; workers must follow special procedures for their own safety. Or at least, that’s how it’s supposed to work. As we will discuss later, some countries don’t have the same safety regulations.

How Does Cashew Processing Work?

Now you know the factor that makes cashew processing unique. With that in mind, let’s examine the standard steps factories use to prepare cashews for consumption.

Heating the raw cashews

It all starts with heating the raw cashews. The best ways to do this are steaming, boiling, or roasting them. This step serves two purposes:

  1. To soften and loosen the hard shell, making it easier to remove.
  2. To make the CNSL less aggressive and less likely to cause skin reactions.

Shelling the cashews

Workers shell the cashews by hand or by using a machine. And this is the step when workers have to be careful with the CNSL, the toxic oil I mentioned before. When done by hand, workers should wear gloves when removing the nut from its shell to avoid coming into contact with the urushiol present in CNSL.

Empty cashew shells after the shelling process

While machines are increasingly used to shell cashews safely, most cashews are still shelled by hand using a labour-intensive process. The drawbacks of shelling cashews with a machine are hard to ignore for cashew factory owners:

  1. Processing machines are very expensive
  2. The production speed is slower with these machines compared to how fast a skilled worker can be.
  3. The machine is made with curved blades, to be compatible with the cashew’s curvature. Because cashews have slight differences in size and shape, these machines don’t always cut the nut precisely, causing a considerable number of broken kernels. And that makes their value drop.

Drying the cashews

Some factories dry the cashews in an oven before peeling them. The heat helps the skin separate from the kernel, making the peeling process much more manageable. But this step is not always used as it’s an extra cost for the factory.

Peeling the skin

At this point, the cashews need to be peeled. A thin layer of skin covering the kernel, called testa, must be removed. This step is done by hand, and workers must be very careful as the testa is very delicate, and it’s easy to damage the kernel. This inner shell, or skin, is not dangerous to the workers as it doesn’t contain harmful oils.

Grading the cashews

The cashews are now ready for grading. This is essential because it helps determine the product’s final price. The main sorting criteria are:

  • Size
  • Shape
  • Colour

There are many possible grades and classifications. The most valuable cashews are the ones with a white or light yellow colour, with the standard kidney shape. Additionally, being large and whole (without damage) increases their value considerably.

Broken kernels are usually sold as cashew pieces at a lower price because they are not so attractive. Another popular destination for these “damaged goods” is the cashew flour industry.

Quality control

After grading, it’s time for quality control. This is when the final product inspection is done, and fumigation is performed, if necessary.


In the end, the cashews are carefully shipped to the distribution points. Here, cashews are packed in airtight containers to prevent moisture and oxygen from causing damage.

Some Countries use Different Methods

The cashew processing steps we discussed are the standard ones. Yet, some countries don’t have proper safety measures in place. As a result, this work becomes more hazardous, as the workers are exposed to the harmful oils in the outer shell of cashews.

Let’s take India as an example, which is one of the top cashew producers and exporters. In most cashew processing factories, salaries are not calculated by the hour, but by the volume of nuts a worker can prepare. On average, Indian workers receive from $4 to $6 per day.

Such low wages often lead to workers handling the toxic shells carelessly, in an attempt to speed up the process. Many say that gloves slow them down and prefer to remove the cashew from its shell with their bare hands. It’s normal to see workers in these factories with black fingers resulting from years of handling these toxic shells.

Raw Materials obtained when processing cashews

In addition to their value as a nut, cashews are also valuable for their by-products.

Cashew nutshell liquid (CNSL)

Cashew nut shell liquid in a flask

The cashew shell contains CNSL. Some studies show much promise for CNSL in the fuel industry, testing it as an alternative to diesel fuel.

This oil is one of the best natural sources of phenol, an ingredient with many valuable uses, such as medicines, resins, pesticides, and paints.

Cardanol can also be obtained from anacardic acid (the main component of CNSL). It’s used to produce many industrial products, such as varnishes, resins, paints, etc.

Cashew Testa

Cashew testa skin after peeling

The testa is known by different names, such as cashew skin, inner shell, and cashew husk. It’s the thin layer of skin that covers the kernel, and it’s usually discarded after peeling the nuts.

While it is not suitable for human consumption, it has various uses. For example, it can be used as a tanning agent in the leather industry. Additionally, the cashew testa skin can be used as animal feed. This is because it is high in protein and fat.


Wrapping up, the journey of cashews from tree to table is fascinating. It’s filled with precise steps and careful handling. The presence of the toxic cashew nut shell liquid (CNSL) adds an intriguing twist to the processing of these nuts. Since this substance is so dangerous, extra precautions are required. Even the so-called “raw” cashews undergo a similar process, debunking the myth that they are completely unprocessed.

The process is not just about getting the edible nut; it also yields valuable by-products like CNSL, which holds potential in industries ranging from fuel to medicine.

So, the next time you munch on a handful of these kidney-shaped delights, remember their journey. Appreciate the meticulous work needed to make them safe and enjoyable for your consumption. It’s a testament to human ingenuity, turning a naturally toxic product into a beloved snack enjoyed worldwide.

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