Besides being particularly loved for their taste and their sweetness, cashews are among the most consumed and used nuts worldwide, also in the kitchen. But what are they exactly?
Let’s discover together their main features:
Botanical aspects
The cashew tree belongs to the Anacardiaceae family, while the genus that gave the name to the entire family is Anacardium, which comprehends eight species of tropical trees that are native to South America. Among these there is the most common and interesting from a business point of view, i.e. the cashew (Anacardium occidentale L.).
The tree is an evergreen plant that can reach a height of up to 10-12 meters and can develop a foliage of about 25 meters in diameter. It is native to the Amazon Basin, in north-eastern Brazil, and is widely cultivated in tropical regions all over the world. It was the Portuguese who introduced it to the west coast of India and East Africa. It is now often found in coastal areas both in warm temperate climate regions and in dry tropical climate zones as well as in equatorial rainforests.
In order to develop and grow, cashews need a temperature of approx. 24-28°C. It does not resist frost, which is why it is not possible to grow this plant in Europe.
A cashew tree begins to produce its fruit three years after it has been planted, although full productivity is reached after about ten years. Each plant can produce up to 48 kilograms of cashews per year.
Fruits
The cashew tree produces two types of fruit:
- a false fresh fruit, also known as cashew apple (also known as acajù apple in Brazil): it is a fruit that vaguely resembles a heart, from which the name of the plant derives, and which can take on a colour varying between yellow and red. The fruit is mainly eaten fresh in the country of origin or is used to be processed into jam. During the harvesting season, the fruit, which has an acidulous and refreshing taste, is extracted from the fruit, which can be drunk as it is (Brazil cajuado) or as wine after fermentation. The juice, if left exposed to air, will turn black and can thus be used as natural ink.
- the true nut, namely the cashew almond or nut (known as acajù nut in Brazil): it is the case of a “true fruit” because the new plant will originate from this part of the fruit. The nut is mainly exported from the producing countries to be consumed as it is or to be roasted or fried. The cashew nut is a kidney-shaped nut (approx. 3 cm in length and 2.5 cm in width) that grows in the lower outer part of the false fruit and has a hard pericarp (part of the fruit protecting the seed) containing the edible seed.
Production and processing
Currently the main producing countries are Vietnam, India, the Philippines, Tanzania, Guinea-Bissau, Benin, Mozambique, Brazil and Indonesia.
Before being consumed, cashews undergo a rather complex and delicate processing that starts with their cleaning, their immersion in water and the roasting process. The ripen fruits falling from the trees are left to dry on the ground for a few days; during such time it is very important that the climate is dry in order to prevent the nuts from sprouting.
Afterwards, the raw nuts are harvested, cleaned and immersed in water to increase the moisture content of the seeds (wetting stage). At this point the roasting stage of the nuts in shell takes place: during this stage the shell releases a very caustic oily liquid called CNSL (Cashew Nut Shell Liquid) which, thanks to its characteristics of impermeability, resistance to heat, friction, acids and corrosive substances, can be used as a raw material in many industrial processes: production of brake linings, clutch discs, waterproof paints and plastic materials. The release of this liquid is one of the reasons why cashew nuts cannot be found in shell on the market, but only as shelled fruits.
At this point the shelling stage can take place: during the shelling phase it is important to make sure that the seeds remain intact and clean. In India this operation has always been carried out by hand, however there are semi-automatic or automatic shelling systems that guarantee a good percentage of whole fruit yield: shelling with blades, with an awl or by means of a rotating blade. After the shelling stage, the seeds must be separated from the shell fragments and nuts that are still closed.
At this point the stages that will make the clean seeds available on the market begins:
- Drying: this stage allows to remove the outer cuticles of the seeds. It takes place at a temperature of 70°C for about 6 hours.
- Removal of the cuticle: after its roasting, the external cuticle can be removed by hand by rubbing the seeds between your fingers, or by using vacuum cleaners or air jets.
- Calibration: cashews are measured and divided according to their calibre.
- Remoistening: in order for the cashews to be sold, they need to be slightly remoistened in order to avoid breakages during the packaging stage. They are brought to a humidity percentage of 3-5%.
- Packaging: cashews are pretty sensitive to rancidity, so the packaging must be waterproof and the air in the package must be replaced with an inert gas. This sensitivity to rancidity increases with roasting or frying, so in this case it is necessary to store them in vacuum or protective atmosphere packs.
Commercial features
From a commercial point of view, cashews are classified according to the dimensions of the fruit and the colour, that is due to the roasting and drying stage to which the cashews are subject before being exported.
On the basis of their colours, cashews are divided as follows:
- in India: the lighter product is identified with W (White Wholes), the intermediate gradation with SW (Scorched Wholes) and the darker ones with SSW (Scorched Wholes Second) and DW (Dessert Wholes).
- in Brazil: the W1 colour represents white, W2 an intermediate shade and W3 the darker shade.
Whole cashews of W and SW gradation are further subdivided according to size, i.e. the number of fruits contained in a pound (454 g). The possible sizes are 180, 210, 240, 320, 450 and 500, of which the most commonly imported in Italy is 320.
Nutritional values
When it comes to cashews and to nuts in general, the recommended daily portion usually amounts to 30 g that, in the specific case of cashews, corresponds to approx. 15-20 fruits.
Like other types of nuts, cashews are an excellent source of unsaturated fatty acids (mono and polyunsaturated) that account for about 83% of total fat. The substitution of saturated fats with unsaturated fats in the diet contributes to the maintenance of normal levels of cholesterol in the blood, thus helping to prevent the onset of diseases affecting the cardiovascular system. They are also a good source of protein: in fact, a 30 g portion of cashews provides the body with about 6 g of vegetable protein.
From a nutritional point of view, besides macronutrients, a portion of 30 g of cashews also delivers several fundamental microelements for the maintenance of a good health: among these are some important minerals such as magnesium, that contributes to the reduction of the sense of tiredness, phosphor, copper, manganese and selenium, that contributes to the normal functioning of the immune system. Cashews also represent a source of several important vitamins such as thiamine, vitamin B6, biotin, vitamin K and vitamin E, the latest being particularly useful as it contributes to the reduction of oxidative stress acting thus as antioxidant.
Source:
Nutsbook – Nuts for Life