Countries and regions such as India, Brazil, Bangladesh, Tanzania, Kenya, Mozambique, tropical regions of Africa and South-East and Far-East Asia, produce cashew nuts and CNSL in abundant quantities. Also, many countries import raw cashew nuts for processing, thus, producing CNSL as a byproduct. The shells separated from cashew nuts are processed to give CNSL, and is thus a byproduct of the cashew processing industry.Īs a result of large scale commercial cashew plantations, CNSL is available in many countries across the world.
The soft honeycomb structure of the shells secretes a dark reddish brown viscous oily liquid. This shell is of about 1/8 th inch in thickness. The cashew seed shell is separated to give cashew nut. Cashew nut shell liquid has a reddish-brown colour due to charring as well as chemicals changes during frying. The kidney shaped nut varies in size from 2.5 to 4 cm. The nut or kernel inside the shell is covered with a brown skin known as testa. The honeycomb structure is housed between the inner and outer shells. The inner wall or shell is harder and needs to be cracked to remove the nut inside. When the cashew nut matures, the outer shell becomes grayish-brown. As these substances are skin allergens, they are dangerous in manual processing of cashew nuts.Ĭashew nut has two shells (double shell) or walls, the outer one being smooth and somewhat elastic and olive green in colour before maturity. Therefore, usually, cashew nuts are sold to consumers only after removal of these shells. The shell can cause contact dermatitis similar to poison ivy, due to the presence of phenolic lipids, anacardic acid and cardanol. This seed is surrounded by a double shell that contains an allergenic phenolic resin, anacardic acid – which is a potent skin irritant. This drupe or true fruit of cashew contains a single seed, which is often considered a nut. This drupe first develops on the tree and then the pedicel expands to become the cashew apple. The true fruit of cashew is a kidney-shaped drupe that grows at the end of the cashew apple. The cashew apple is light reddish to yellow coloured, soft and fleshy fruit, whose pulp and juice can be processed into a sweet, astringent fruit drink or fermented and distilled to produce liquor. The bottom end of the cashew apple is attached to the cashew nut encased in a shell. The top end of the cashew apple is attached to the stem of cashew tree.
It ripens into a yellow or red fruit about five to eleven cm (2 to 4.3 inches) long.
This cashew apple is an oval or pear-shaped hypocarpium that develops from pedicel and the receptacle of the cashew flower. It is also known as pseudocarp or false fruit. In botanical terms, some of the flesh of accessory fruit is derived from some adjacent tissue exterior to the carpel and not from the floral ovary. This means, the cashew seeds is not present inside the fruit, cashew apple, but outside it. The tree produces cashew seed and the accessory fruit, cashew apple. The cashew nut yields for the traditional tree are about 0.25 MT per hectare, while yields for the dwarf variety are more than one tonne (1 MT) per hectare.Ĭashew tree is a tropical green tree and has the botanical name Anacardium occidentale. The recent breeds such as the dwarf cashew trees (up to 6 m tall) begin to give economic yields after three years. Traditional cashew trees are tall (up to 14 m) and their economic harvests begin eight years after planting. The present paper presents an overview of properties, components of cashew nut shell liquid (CNSL) and its manufacturing processes.Ĭashew trees are cultivated in the tropical regions and are well-adapted to low-land areas with a pronounced dry season, where the mango and tamarind trees also thrive. Cashew nut shells are used to produce cashew nut shell liquid, known in short as CNSL. The shell of the popular dry fruit, cashew nut, is an important source or the starting material for several specialty chemicals.
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