CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Although yams and sweet potatoes are both angiosperms (flowering plants), they are not related botanically. Yams are a monocot (a plant having one embryonic seed leaf) and from the Dioscoreaceae or Yam family. Sweet Potatoes, often called ‘yams’, are a dicot (a plant having two embryonic seed leaves) and are from the Convolvulacea or morning glory family (Peggy, 2017).
Many times the names “sweet potato” and “yam” are used interchangeably in conversation, in cooking and even at the supermarket. But they are really two different vegetables. In fact, although they are both root vegetables, they belong to two different plant families-the sweet potato is from the morning glory family while the yam is related to the lily. Yams are sweeter than the sweet potato, grow much larger and are also nutritionally inferior.
The sweet potato (Ipomoea batatas) is a dicotyledonous plant that belongs to the bindweed or morning glory family, Convolvulaceae. Its large, starchy, sweet-tasting, tuberous roots are a root vegetable (Purseglove, 2008). The young leaves and shoots are sometimes eaten as greens. The sweet potato is only distantly related to the potato (Solanum tuberosum) and does not belong to the nightshade family, Solanaceae, but both families belong to the same taxonomic order, the Solanales (Woolfe, 1992).
Yam is the common name for some plant species in the genus Dioscorea (family Dioscoreaceae) that form edible tubers. Yams are perennial herbaceous vines cultivated for the consumption of their starchy tubers in many temperate and subtropical world regions. The tubers themselves are also called “yams”, having numerous cultivars.
1.2 STATEMENT OF THE PROBLEM
The fact that sweet potatoes and yams are mislabeled on cans and in recipes can cause a lot of confusion. There are two main types of sweet potatoes, both of which are elongated yellow or orange tubers that taper to a point at each end. The paler-skinned sweet potato has a thin, light yellow skin and pale yellow flesh. It's not sweet and has a dry, crumbly texture similar to a white baking potato. The darker-skinned variety (which is most often and incorrectly called a yam) has a thicker, dark orange to reddish skin with a sweet, vivid orange flesh and a moist texture.