1. INTRODUCTION
The cashew nut (Anacardium occidentale) produces nuts, the kernels of which have increased considerably in economic importance over the past few decades. Indigenous to Brazil, the cashew was taken to West Africa, East Africa and India by the Portuguese in the 15th and 16th centuries. It was noticed that the tree grew well on poor sandy soils along the coastal belt and was used by the Portuguese in Africa as an anti-soil erosion measure. The tree prospered and spread naturally, particularly in East Africa and India and the progeny of these wild cashew has formed the basis of the raw material for the cashew industry. Though the plant was primarily intended for checking soil erosion, it is now mainly grown for its commercially important kernel and shell oil (Aiyadurai, 1963).
After the war in 1945, world production and consumption of cashew nut increased sharply and it soon became the worlds most important dessert nut after almonds. World consumption of cashew nuts has been increasing steadily from 125,000 tons in 1955 to 1,000,000 tons in 1995, and is estimated to be around 1,260,000 tons by the year 2005 (Ohler, 1979). The production of cashew nut has also kept pace with demand in Europe and Africa and the increase in production has been achieved mainly through extension of the area under the crop. The production of cashew nut in India, however, is far short of the capacity of the existing processing industries and consequently, the cashew industry in India has been stagnant for the past two decades. To increase yields, improved planting material and better crop management practices will have to be given some attention (Russel, 1979).
Other countries in South East Asia and the Pacific region including many islands in Indonesia where the cashew nut as well as the cashew apple are appreciated. In Malaysia, where its suitability for cultivation has been shown and the Philippines where its economic potential has yet to be exploited are some of the new areas with future potential although labor requirements seem to be prohibitive, especially in Australia where conditions also appear suitable for its cultivation.
Trends in production of cashew are also related to consumption and these in turn will depend on the world economic situation. With the increase in the standard of living in developing countries, a large consumer market is developing, especially in cashew producing countries (Ohler, 1979). There is also the need to explore the possibility of wider dietary utilization of the oil obtained from the shell during processing of raw nuts, which is also a potential exportable product.
2. NUTRITIVE VALUE/COMPOSITION
Cashew is a highly nutritious and concentrated form of food, providing a substantial amount of energy. The cashew nut kernel has a pleasant taste and flavor and can be eaten raw, fried and sometimes salted or sweetened with sugar (Manay et al, 1987). It also contributes as an important source of invisible fat in the diet, being widely used in a variety of ways. There has been a growing demand for cashew in many temperate countries where the demand is increasing (Russel, 1979). The nut contains an acrid compound which is a powerful vessicant that is abrasive to the skin. The cashew shell contains 25% of this reddish brown oil, industrially known as Cashew Nut Shell Liquid (CNSL) which is a by-product of the roasting process.
2.1 Overall Composition
The kernel is considered to be of high nutritive quality and growing conditions or the variety of cashew may have an influence on kernel composition (Ohler, 1979). The overall composition of the kernel is protein 21%, fat 46% and carbohydrates 25%.
2.2 Total Nutrient Content
The total nutritive value of 100 g of cashew nut is presented in Table 1.
Table 1. Nutritive Value in 100 g of Cashew Nut
Moisture |
5.9 |
Total Minerals |
2.4 |
Total Fiber |
1.3 |
Energy |
785 |
Protein |
24 |
Total Fat |
64 |
Saturated |
12.9 |
Unsaturated (Oleic) |
36.8 |
Unsaturated (Linoleic) |
10.2 |
Carbohydrate |
41 |
Ca |
53 |
P |
52.2 |
Fe |
5.3 |
Thiamin |
0.63 |
Riboflavin |
0.19 |
Niacin |
2.5 |
Beta-carotene |
60 |
Retinol Equivalent |
33 IU; 10 mcg |
Vitamin K |
650 |
Wide differences in the protein content ranging from 13.13 to 25.03% have been reported from various regions of India. It has been suggested that protein content be considered as one of the most important factors in future breeding and selection programs on cashew nut. The amino acid composition of kernel protein has been reported by various experts (Table 2).
Table 2. Amino-Acid Composition of Cashew Kernel Protein
Amino Acid |
Composition (%) |
Glutamic Acid |
28.0 |
Leucine |
11.93 |
Iso Leucine |
3.86 |
Alanine |
3.18 |
Phenylalanine |
4.35 |
Tyrosine |
3.20 |
Arginine |
10.30 |
Glycine |
5.33 |
Histidine |
1.81 |
Lysine |
3.32 |
Methionine |
1.30 |
Cystine |
1.02 |
Threonine |
2.78 |
Valine |
4.53 |
Tryptophane |
1.37 |
Aspartic Acid |
10.78 |
Proline |
3.72 |
Serine |
5.76 |
Analysis of cashew nut kernels from different regions of India have revealed that there are variations in the reducing sugar content from 1% to 3% and the non-reducing sugars from 2.4% to 8.7%. Starch content ranged from 4.6% to 11.2% and the oil content also showed a wide variability from 34.5% to 46.8%.
2.5 Fatty Acid Composition
The fat and oil content of cashew nut contributes substantially to its energy content and consists mostly of glycerides of oleic acid (73.8%) and linoleic acids (7.7%) (Ohler, 1979). Table 3 gives the composition of fats in cashew kernels.
Table 3. Fatty Acid Composition of Cashew Kernels (%)
Oleic Acid |
73.3 |
Linoleic Acid |
7.67 |
Palmitic Acid |
0.89 |
Stearic Acid |
11.24 |
Lignoseric Acid |
0.15 |
Unsaponifiable Matter |
0.42 |
WHO/FAO (1977) had recommended an LA intake of over 3 en %, the requirement of LA being around 8g/capita/day. In rural diets, the invisible fat present in cereals, pulses and milk can meet about 66% of the daily LA requirements. To furnish the remaining 33%, different amounts of vegetable oils would be required from various sources of nuts and oil seeds. In the Indian context, figures available for two edible oils furnishing the recommended intake of LA works out to be 11 g or 4 en % in the adult diet, wherein the fat intake of total calories would be 11% or 30 g.
The judicious use of cashew in the diet in suitable proportions so as to enhance dietary quality with respect to fat and protein should therefore be possible. Owing to its high protein content, it could be used along with cereals/staples and pulses in small amounts in association with vegetables to improve the dietary profile. The level of oil present in the cashew to ensure energy density in the diet appears to be adequate, but whether it can meet with the diets LA requirements needs to be studied further.
2.5 Vitamin Content
The vitamin content of cashew nut kernels shown in Table 4 indicates that 0.5 to 1.4 mg per 100 g of thiamin and 0.58 mg per 100 g of riboflavin, a good proportion of vitamin E and traces of other vitamins are present in cashew.
Table 4. Vitamin Content (mg per 100 gm) of Cashew Kernels
Thiamin |
0.56 |
Niacin |
3.68 |
Riboflavin |
0.58 |
Tocopherol |
210 |
Pyridoxine |
traces |
Axerophtol |
traces |
Vitamin D |
traces |
Thus, the amounts of cashew to be incorporated and the economic feasibility in utilizing for local diets need to be critically examined. Cardiovascular diseases which affect individuals mostly around middle age is common among the more affluent. The use of small amounts of cashew nut in the diet could therefore be a deterrent in controlling cardiovascular ailments.
2.6 Mineral Content
The mineral content of cashew kernel (Table 5) appear to be minimal as compared to the higher mineral content of the cashew apple, especially the high Vitamin C content (240 mg). Most citrus species such as orange have only 45 mg of Vitamin C. However, the cashew apple is yet to be utilized on a large scale to alleviate Vitamin C nutrition requirements in the tropical countries where the crop is grown.
Cashew is also one of the few sources of phenols (contains about 60 % of anacardic acid by weight). This acid is responsible for the vesicative activity of the shell liquid extract and can cause acute dermatitis. It is therefore essential to ensure that as little contamination as possible of CNSL should occur during processing of kernels. In traditional medicine however, this extract has been used successfully (Ohler, 1979).
The high price of cashew kernels will certainly stimulate the planting programs in various countries. Since the cashew nut market competes with other nuts, there is bound to be increased production of all nuts. The present cost of processing cashew is much higher as compared to other nuts which allows little flexibility in cashew kernel prices. It is therefore necessary to develop more efficient and cost-effective processing systems for cashew (Russel, 1979).
Table 5. Mineral Content of Cashew Kernels (%)
Ca |
0.04 |
P |
0.88 |
Na |
0.005 |
K |
0.57 |
Mg |
0.28 |
Fe |
0.008 |
Cu |
0.002 |
Zn |
0.004 |
Mn |
0.002 |
In contrast, groundnut (Arachis hypogea) which is also an important oil crop of Brazilian origin, is now cultivated in tropical and warm temperate climates. The Portuguese were initially responsible for introducing the crop to Goa, India and the rest of Asia and Africa. With 31 % of the worlds production, India ranks first in groundnut production today. Groundnuts are not only rich in proteins which are easily digestible and consequently, a higher biological value, but are also rich in B-complex vitamins. Like other edible nuts it is used in different ways and it is an essential item in several confectionery products, and in supplementary feeding programs such as in weaning food formulations in combination with cereals and pulses in many developing countries. Various cultivars of groundnut tested in Andhra Pradesh, Southern India have shown high contents of P and K, possibly due to varietal differences (Pillai et al, 1984). There is a similar need to investigate the variability in mineral content of cashew nut varieties in order to produce better varieties and optimize their use.
Whilst groundnut, when processed into margarine is gaining popularity as a substitute for butter in the USA and elsewhere, specifically due to its alternate use in instances of lactose intolerance, it is fast replacing dairy products due to the absence of cholesterol. The principal use of groundnut however, is in the production of oil (Cummins, 1986).
2.8 Comparative Nutritive Value of Groundnut vs Cashew Nut
The comparative proximate composition of groundnut and cashew nut is given in Table 6. The nutritive value of both nuts are apparently similar with the exception of iron, where cashew nut has twice the level of groundnut as well as the chromium content which is higher in cashew. The bio-availability of these minerals need to be studied as cashew also has a high oxalate content. This aspect need to be investigated in view of its possible application in meeting the iron requirements of vegetarian diets which are usually deficient in iron. The presence of chromium can also help in formulating better diets for diabetics.
Table 6. Comparative Nutritive Value of Cashew Nut and Groundnut
|
Cashew Nut |
Groundnut |
Energy Keal |
596 |
567 |
Protein (g) |
21.2 |
25.3 |
Fat (g) |
46.9 |
40.1 |
Minerals (mg) |
2.4 |
2.4 |
Fiber (g) |
1.3 |
3.1 |
Carbohydrates (g) |
22.3 |
26.1 |
Calcium (mg) |
50 |
90 |
P (mg) |
450 |
350 |
Fe (mg) |
5.81 |
2.5 |
Cr (mg) |
0.163 |
0.048 |
Table 7. Total Fatty Acid Composition of Groundnut Oil
Saturated |
20 |
Monounsaturated |
54 |
Oleic |
47 |
Polyunsaturated |
26 |
Linoleic |
28 |
REFERENCES
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Pillai, R. N., Ranganakulu, G., Padma Raju, A., Sankara Reddi, G.H (1984). Mineral Composition of Kernels and Shells of Four Cultivars of Groundnut. Andhra Pradesh Journ. (India). 31 (4): 351-352.
Russel (1979). Cashew nut Processing. FAO Agricultural Services Bulletin. Third Ed. FAO, Rome.