Starches and Starchy Roots

Starches and Starchy Roots :

1. CASSAVA
– energy yields per hectare from cassava roots are often very high
– contains less than 1 percent protein (in maize and other cereals in maize and other cereals more than 10 percent)
– also has less iron and B vitamins than the cereal grains.
– kwashiorkor is much more common in young children weaned on to cassava than in those weaned on to millet or maize.
– Cassava, particularly bitter varieties, contains a cyanogenic glucoside
– Can make tapioca, which is mainly cassava starch
– Cassava leaves:
• their nutritive value is similar to that of other dark green leaves.
• source of carotene (vitamin A), vitamin C, iron and calcium.
• also contain some protein.
• to preserve the maximum quantity of vitamin C in the leaves, they should not be cooked for longer than about 20 minutes

2. SWEET POTATOES
– Sweet potatoes originated in the Americas
– Usually from stem cuttings.
– Contain little protein.
– Contain some vitamin C, and
– Tthe coloured varieties, especially the yellow ones, provide useful quantities of carotene (provitamin A).
– Sweet-potato leaves are often eaten and have properties very similar to those of cassava leaves.
– However, the leaves should not be picked to excess since, as with other tuber crops, this may reduce the yield of tubers.

3. YAMS
– There are innumerable varieties of yams (genus Dioscorea), some of which are indigenous to Africa, Asia and the Americas.
– They vary in shape, colour and size as well as in cooking quality, leaf structure and palatability.
– The many domesticated and wild varieties are eaten.
– Usually contain about twice as much protein (2 percent) as cassava, although very much less than cereals

4. TARO or COCOYAMS (Colocasia sp.)
– originated in Asia
– grown in areas where there is fairly high rainfall spread over much of the year.
– Both the tubers and the leaves are eaten.
– The nutritive value of taro is similar to that of cassava.

5. POTATOES
– first taken to Europe from South America
– became a cheap, useful, high-yielding alternative to the existing main staples
– they are grown in higher cool areas
– contain only about 2 percent protein, but the protein is of reasonably good quality.
– provide small quantities of B vitamins and minerals.
– contain about 15 mg vitamin C per 100 g, but this amount is reduced in storage.
– the keeping quality of potatoes is not good, unless they are stored carefully.

6. ARROWROOT
– is grown in areas with adequate rainfall
– the nutritive value of arrowroot is similar to that of potatoes.
– the roots are eaten in a variety of ways, often roasted or boiled.