Investigating carotenoid loss after drying and storage of

5
1. Literature review
food corresponds to one retinol activity equivalent (RAE). A recent study in mashed
sweet potato reported a conversion factor of 13:1 (13 µg of "-carotene in mashed sweet
potato equivalent to 1 µg retinol equivalent (RE) (Haskell et al. 2004).
Two more recent studies (van Jaarsveld et al. 2005; Low et al. 2007) in South Africa and
Mozambique respectively have demonstrated that regular consumption of orange-fleshed
sweet potato (OFSP) significantly increased vitamin A status of children. The South
African study (van Jaarsveld et al. 2005) measured the impact of the consumption of
OFSP on primary-school children. The serum retinol of children (n=90) who consumed
OFSP was significantly higher as compared with the serum retinol of children
consuming white-fleshed sweet potato (WFSP) after 53 school-days. It proved that the
consumption of OFSP significantly increased vitamin A status of children. On the other
hand, the study undertaken by Low et al. (2007) in Mozambique consisted of a two-
year-integrated agricultural and nutrition intervention promoting OFSP consumption
involving households and young children (ca. n=400) through two agricultural cycles.
The outcome of the integrated approach also showed that in a rural setting the serum
retinol of young children consuming OFSP significantly improved. Moreover the mean
plot size of fields devoted to OFSP was nearly ten times higher in the second year.
OFSP also emerged as the least expensive source of vitamin A in local markets. This
second study further proved that OFSP, as part of an integrated agricultural and nutrition
approach, could potentially play a significant role in tackling vitamin A deficiency in
developing countries.
1.1.3 Importance of sweet potato
Sweet potato (Ipomea batata (L.) Lam.) is a dicotyledonous plant from the
Convolvulacae family. It is an important crop in food systems in Eastern and Southern
Africa. Cultivated in more than 100 countries, sweet potato ranks third of the world root
and tuber crops production after potato and cassava (FAOstat 2008). In developing
countries, sweet potato is especially valuable because it is a food security crop for the
poor that can provide an important part of the dietary carbohydrate of the population
(Hagenimana and Owori 1996). Sweet potato grows well in tropical areas, where the
majority of poorest people live, and it yields relatively better than most of the major
crops under tropical climates (Woolfe 1992). World production has been estimated at
110 million tonnes per annum (FAOstat 2008). Asia is the world’s largest producer with