LITERATURE REVIEW INTRODUCTION South Africa has adiversity of cultures with their traditional foods. These cultures have forseveral years prepared and enjoyed traditional dishes which have kept them wellnourished (Khumalo, 2004). Those were times when rural communities were stillowning vast areas of land and large herds of cattle. Immigration and theintroduction of western and eastern dishes have caused the traditional foods togradually vanish. The AgriculturalResearch Council and genebank of the National Department of Agriculture has recordeda very limited collections of wild vegetables such as Corchorus Olitorius fromthe whole country and there is no single genetic material on wild vegetablesfrom northern Kwazulu-Natal held in the national genebank. There is equally noinformation on processing and chemical evaluation of species. (F.
B Lewu etS.Mavengahama, 2010) Beside the fact thatedible indigenous plant have been used as food for years (Vorster et al. 2008;Adebooye and Opabode 2004), some recent publication indicated that the use of wildvegetables in South Africa is in decline (Steyn et al.
2001; Modi et al.,2006). (Flyman and Afolayan,2006b) have suggested that the lack of knowledge about nutritional composition,cooking methods and ways of preservation are considered as reasons for low useof wild vegetables in the Southern Africa. (A.T Modi et al.
, 2013)described amadumbe Colocasia esculenta(L.)Schott as a neglected and underutilised crop in sub-Saharan Africa dueto insufficient agronomic informations on it. Current literature doesnot provide enough informations on amadumbe (Colocasia Esculenta) in many aspects such as physiology, productionin South Africa and processing by drying. However, this studywill focus on exploring some information available on Amadumbe as well as itsdrying behaviour under several drying temperatures in an industrial tray dryer.
Thus, the major pointswhich will be discussed in this this review are: Amadumbeoverview,drying,drying mechanism of tuber, drying curves, drying systems,evaluation:productand dryer,determination of energy required to dry amadumbe, Mathematicalmodelling of the drying characteristics of amadumbe . Amadumbe overview Amadumbe (Colocasiaesculenta), also called taro, is bred for its edible corms in subtropicaland tropical regions of the world. Rich in carbohydrates and energy, it is oneof the staple foods in the developing countries of Africa, the West Indies andAsia (Liu, Donner, Yin, Huang, & Fan, 2006).In South Africa, amadumbe is consideredas traditional crop cultivated by ruralfarmers in KwaZulu-Natal for subsistence. Beside the cultivated one, amadumbealso grows in the wild.
Cultivated amadumbe (Colocasia esculenta varesculenta) is grown on dry land and consistsof poorly developed stolons. However, wild amad-umbe (Colocasia esculenta var. stolonifera) is adapted to wet land andpossesses well-developed stolons. Fig.1Amadumbe corms from cultivated and wild sources.A: cultivated: Colocasia esculenta var esculenta, B:wild: Colocasia esculenta var stolonifera.
Nutritional valuesand use According to (Chay-Prove and Goebel, 2004), theamadumbe leaves are generally not eaten, but some traditional communities douse them like any green vegetable. The starchy corm is the one most eaten bypeople and also marketed by countries like Australia, New Guinea, Sunda Islandand South Africa. Amadumbe do not have stems but have long petioles, which arealso rich in nutrients. Nutritional information of amadumbe appears in table1.1, and shows comparison of major nutrients. Table 1.
1 Amadumbe Nutritive values(Langenhoven et al., 1991) Components Per 100g edible portion Corm leaves Petioles Edible portion (%) 81 55 84 Energy (kilojoules) 257 289,8 79.8 Moisture (%) 77.5 79.6 93.8 Protein (g) 2.
5 4.4 0.2 Fat (g) 0.
2 1.8 0.2 Carbohydrate (g) 19 12.
2 4.6 Fibre (g) 0.4 3.4 0.6 Calcium (mg) 32 268 57 Phosphorus (mg) 64 78 23 Sodium (mg) 7 11 5 Potassium (mg) 514 1237 367 Iron (mg) 0.
8 4.3 1.4 VitA (IU) Trace 20385 335 Thiamine (mg) 0.18 0.1 0.
01 Riboflavin (mg) 0.04 0.33 0.
02 Niacin (mg) 0.9 2 0.2 ascorbic acid (vit C) mg 10 145 8 Table 1.
1 displays major nutrients contained indifferent parts of the plant. It appears that the corm has the highestpercentage of energy which is 257 kilojoules, with 19g carbohydrates and 0.18mgthiamine .Twelvemajor nutrients are higher in the leaves than any other part of the crop, whilepetioles are only high in moisture, fibre and edible portion. Taro can be usedas a substitute to cereals and consumed by children sensitive to milk (Lee,1999)