Cocoyams are herbaceous perennial plants belonging to the family Araceae and are grown primarily for their edible roots, although all parts of the plant are edible (Akomas, Mbanaso & Akoma, 2007). Cocoyams that are cultivated as food crops belong to either the genus Colocasia or the genus Xanthosoma and generally consist of a large spherical corm (swollen underground storage stem), from which a few large leaves emerge. The petioles of the leaves stand erect and can reach lengths in excess of 1 m (3.3 ft). The leaf blades are large and heart-shaped and can reach 50 cm (15.8 in) in length.
The corm produces lateral buds which give rise to tubers or cormels and suckers or stolons. Cocoyams commonly reach in excess of 1 m (3.3 ft) in height and although they are perennials, they are often grown as annuals, harvested after one season. Colocasia species may also be referred to as taro, old cocoyam, arrowroot, eddoe, macabo or dasheen. Xanthosoma species may be referred to as tannia, yautia, new cocoyam or Chinese taro (Bremiller, 2013).
Varieties of cocoyam
Rickard (2011) stated that there are two varieties of cocoyam, namely; xanthosoma species and the colocasia species.
- Xanthosoma species: Xanthosoma specie is one of the two types of cocoyam. The name is derived from the Greek words “xanthos”, meaning “yellow,” and “soma”, meaning “body.” This refers to the stigma or yellow inner tissues of this specie of cocoyam. It is grown for its starchy corms, an important food staple of tropical regions. It is popularly referred to as elephant ear (from the purported resemblance of the leaf to an elephant’s ear). The leaves of most Xanthosoma species are 40-200 cm long, arrowhead-shaped or subdivided into three or as many as 18 segments (Akpan & Umoh, 2012).
- Colocasia species: Colocasia specie of cocoyam are herbaceous perennial plants with a large corm on or just below the ground surface. The leaves are large to very large, 20–150 cm (7.9–59.1 in) long, with a arrow-headed shape, dark green above and light green beneath, triangular-ovate, sub-rounded and mucronate at apex, tip of the basal lobes rounded (Carpenter & Steinke, 2010) .
Origin/historical background of cocoyam
According to Asumugha and Uwalaka (2010), Xanthosoma, or new cocoyam, had its origin in South America and the Caribbean. The Spanish and Portuguese introduced it to Europe and were also responsible for spreading it to Asia. It moved from the Caribbean in the late nineteenth century, first to Sierra Leone and then to Ghana. In West Africa, Xanthosoma is more important than Colocasia, being popular for its corm, cormels, leaves and young stems. Although Xanthosoma is relatively new to the Pacific region, it has spread rapidly and widely, becoming quite an important crop in many of the islands. It is also widely cultivated in Puerto Rico, the Dominican Republic and Cuba and is important along the coastal mountains of South America, in the Amazon basin and in Central America.
Colocasia originated in India and Southeast Asia. About 2,000 years ago it spread to Egypt and thence to Europe (Ayele & Nip, 2014). Subsequently it was taken from Spain to tropical America and then to West Africa. It was used in feeding slaves and was transferred to the West Indies with the slave trade (Onwueme, 2007). In order to distinguish it from the newer species, Xanthosoma, Colocasia was referred to as “old yam” in West Africa whereas Xanthosoma is called “new yam”. Colocasia is a staple food in many islands of the South Pacific, such as Tonga and Western Samoa, and in Papua New Guinea. Colocasia and Xanthosoma will tolerate shade conditions and so they are often planted under permanent plantations like banana, coconut, citrus, oil palm and especially cocoa. Therefore they are sometimes collectively referred to as cocoyams.
Nutritional profile of cocoyam
|Nutritional value per 100 g (3.5 oz)|
|Energy||594 kJ (142 kcal)|
|Dietary fiber||5.1 g|
|Thiamine (B1)||(9%) 0.107 mg|
|Riboflavin (B2)||(2%) 0.028 mg|
|Niacin (B3)||(3%) 0.51 mg|
|Pantothenic acid (B5)||(7%) 0.336 mg|
|Vitamin B6||(25%) 0.331 mg|
|Folate (B9)||(5%) 19 μg|
|Vitamin C||(6%) 5 mg|
|Vitamin E||(20%) 2.93 mg|
|Calcium||(2%) 18 mg|
|Iron||(6%) 0.72 mg|
|Magnesium||(8%) 30 mg|
|Manganese||(21%) 0.449 mg|
|Phosphorus||(11%) 76 mg|
|Potassium||(10%) 484 mg|
|Zinc||(3%) 0.27 mg|
(Source: USDA National Nutrient Database, 2014).
Culinary usage of cocoyam
Cocoyam is used in essentially the same way as yam. It can be eaten boiled, fried or pounded into fufu. It can also be made into porridge, as well as chips and flour. It is also used in preparing soups, by boiling whole and the skin peeled while hot, then pounded into a paste and used in soups as a thickener for soups.
Nutritional benefits of cocoyam
According to Wurzburg (2009), cocoyam it is not only high in potassium and fibre, but also contains a significant amount of vitamin E, making the cocoyam a healthy food to add to your diet. Cocoyam is found to be:
- High in fibre: Fibre is an essential nutrient that offers a number of health benefits including reducing your risk of cardiovascular disease, helping you manage your weight and improving bowel movements. An average plate of cooked cocoyam serving (100g) contains 6.7 g of fibre, meeting approximately 25 percent of your daily fiber needs.
- High in vitamin E: Cooked cocoyam is also high in vitamin E with 2.93 mg in a 100g serving. Vitamin E is a fat-soluble vitamin best known for its antioxidant activity, protecting cells from oxidation by free radicals. Including foods rich in antioxidants may offer protection against heart disease and certain types of cancer.
- Potassium-rich: A serving of 100g cooked cocoyam contains 484 mg of potassium. When included as part of a healthy diet, foods high in potassium can help control blood pressure.
- Good source of magnesium: Including cocoyam in diet can help to meet an individual’s magnesium needs. A serving of 100g cooked cocoyam contains 30 mg of magnesium. Magnesium is needed for bone health, muscle and nerve function and immune health. It also helps to keep blood pressure normal and regulates blood sugar.
Health benefits of cocoyam
Cocoyam is loaded with potassium that is an important mineral for a lot of bodily processes. It also includes several calcium, vitamin C, vitamin E and B vitamins, in addition to magnesium, manganese and copper. According to Oti and Akobundu (2008), some of the notable health benefits of cocoyam include:
- Lowers blood pressure: Cocoyam root has elevated levels of Potassium, which manages blood pressure level as well as reduces the chance of hypertension. This really is extremely good for those people who are advanced in years or even are otherwise in a greater risk of creating hypertensive tendencies.
- Lessen cardiovascular diseases: Since cocoyam has got really small amount of fat with no cholesterol, it lowers the chance of cardiovascular illnesses. Individuals who take in cocoyam faces smaller chance of such diseases.
- Stronger immune system: Cocoyam is abundant with Vitamin C; this particular vitamin has got anti-oxidants that really help to combat free-radicals in the body. Cocoyam can also be abundant with Vitamin B6 that fortifies the immune system of our body, making the body much less susceptible to illnesses.
- Rich in dietary fiber: Cocoyam satisfies 27 % in our daily dietary fiber; this is extremely therapeutic for the body. Dietary fibre decreases the chance of colon cancer, helps prevent bowel problems and may also reduce the amount of bad cholesterol within our body.
- Amino acids and omega 3 oils: Cocoyam consists of over 17 various amino acids which are essential for sustaining a healthy body, and in addition it includes life giving Omega 3 as well as 6 oils that are essential for cardiovascular health, cancer prevention, as well as for avoiding disease generally.
Cocoyam is a very important staple food source in Nigeria with several nutritional and health benefits that needed the creation adequate awareness. Based on this, it is recommended that:
- People should be adequately educated on the nutritional and health benefits of cocoyam.
- Cocoyam should be included in the focus and education of farmers on its production
- Encourage and teach farmers to cultivate cocoyam in commercial quantities and various utilizable forms and the methods of their preparation
- Commercial processing of cocoyam to flour, that can be used for baking various snacks and food items like cocoyam macaroni, oats, and custard is recommended to processors.
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Ayele, T. & Nip, W. (2014). Functional properties of raw and precooked taro (Colocasia esculenta) flour. Int J. Food Sci. Techno (IFST) 29:457-462.
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US Department of Agriculture, National Nutrient Database (2014). Nutritional values for cocoyam. New York: USDA.
Wurzburg, O. B. (2009). Modified starches: Properties and uses. Florida: CKC Press Inc.