CASHEW NUT NUTRITIONAL ASPECTS - B.K.Nand

CASHEW

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 15^th and 16^th 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 world’s 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

2.3 Protein ContentWide 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

2.4 Carbohydrate ContentAnalysis 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

It may be mentioned that the high proportion of oleic and stearic acid contents may limit its use in the diets advocating low energy intake. The high content of MUFA oleic however, might be beneficial in cases of bowel enteropathy. Also from the point of view of essential fatty acid requirements, the ratio of linoleic to linolenic (values for cashew nut not available) acid is considered important. Studies at the National Institute of Nutrition (NIN) have shown that cereals and pulses on average contribute 3% and 2% respectively, of invisible fat, providing 1.5% LA and 0.08% ALNA and pulses furnish 1.3% LA and 0.28% ALNA to the diet. On this basis, habitual rural Indian diets were found to provide 7 en % of invisible fat (both from cereals and pulses) (Ghafoorunissa, 1989).

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

It may be mentioned that the vitamin E content of cashew nut could be a beneficial factor, in view of the wider use in the diet of the elderly and those who run the risk of cardiovascular disease. Vitamin E is also a powerful anti-oxidant and its role in lipid metabolism has been well established. Fats containing a lesser amount of tocopherol in the unsaponifiable fraction have been reported to be more atherogenic as compared to most crop species containing higher concentration of tocopherols (Kurup, 1989).

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

2.7 GroundnutIn 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 world’s 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

The fatty acid composition of groundnut is presented in Table 7. The oleic acid content of groundnut is much lower than that of cashew nut, while linoleic acid is three times the level in cashew nut. The WHO/FAO expert group has recommended that 30-35 percent of the Calorie requirements should be met from fats and oils in the ratio of 1:1 of saturated to unsaturated. It is also generally accepted that the total fat in human diets should not exceed 30en % or even lower in sedentary individuals (Fats and oil News, 1988, Grundy et al, 1987). The dietary fat (both visible and invisible) which were so far considered as an important nutrient component merely as a concentrated source of energy, has in recent years assumed tremendous nutritional significance with close links to the quality of fat in relation to its constituent fatty acids. In view of this, it may be of interest to nutritionists and food scientists to evaluate the merits and de-merits of the usage of cashew nuts and groundnuts in the diet in suitable proportions to improve the nutritional fat quality and optimize its dietary benefits and applications.

Table 7. Total Fatty Acid Composition of Groundnut Oil

Saturated	20
Monounsaturated	54
Oleic	47
Polyunsaturated	26
Linoleic	28

REFERENCES

Aiyadurai, S.G. (1963). A review of Research on Spices and Cashew nut in India. Agriculture Commission, Government of India.
Cummins D.G. (1986). Groundnut. The Unpredictable Legume! Production Constraints and Research Needs. Proc. International Symposium, ICRISAT Sahelian Center, Niamey, Niger.
FAO/WHO (1977). Dietary Fats and Oils in Human nutrition. FAO, Food and Nutrition Paper 3, FAO, Rome.
Fats and Oils News (1986). Journ. Amer. Chem. Soc, 63:718.
Gafoorunissa. (1989). Nutritional Aspects in Indian Diets. Proc. Nutr. Soc. India. 35: 43-51.
Gopalan, C. et al. Eds. (1991). Nutritive Value of Indian Foods. (Rev. Ed). NIN, ICMR, Hyderabad.
Grundy, S.M, and Nestle, P.J (1987). Amer. Journ. Clin. Nitrit. 45: 1087.
Kurup, P.A, (1989). Nutritional Factors and Atherosclerosis. Proc. Nutr. Soc. India: 34: 27-36.
Manay, N., and M. Shadaksharaswamy (1987). Facts and Principles. Wiley Eastern Ltd, New Delhi.
Ohler, J.G., (1979). Cashew. Department of Agricultural Research, Royal Tropical Institute, Amsterdam.
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.