Investigating carotenoid loss after drying and storage of

6
1. Literature review
92.5 millions tonnes. China with a production of 85.2 million tonnes represents 77% of
the world sweet potato production (FAOstat 2008). In Asia half of the production is
used for animal feed and the remaining half for human consumption (Woolfe 1992). On
the other hand in sub-Saharan Africa, sweet potato production is 13.7 million tonnes per
annum (FAOstat 2008) representing only 12.4% of the world production, but it is almost
exclusively used for human consumption.
Sweet potatoes are grown from 40°N to 32°S of the equator and on the equator it is
grown from the sea level to 3000m. It has a short harvesting time, 3-8 months from
planting, which is less than most other root and tuber crops (Woolfe 1992). High levels
of nutrition, high productivity and low levels of input have made sweet potato a valuable
resource in the family garden. In particular, it can be a significant resource for families
with low income (Villareal and Griggs 1982). Sweet potato has been playing an
important role as a life saver during food shortages and famines in the history of
humanity. In spite of its numerous qualities, it is much underexploited and this is
probably because of its status as a poor man’s food (Woolfe 1992).
The sweet potato plant can be divided in three elements (Figure 1-2):
Aerial
vine
Underground
part
Leaf
Petiole
Stem
Fibrous root
String root
Storage root
Figure 1-2: Picture showing the morphology of the sweet potato plant. Flowers are
not represented in this. University of Illinois (2006).