Dry and starchy orange-fleshed sweetpotato farmer varieties: Implications for fighting vitamin A defiency in East and Central Africa.

Sweetpotato is a major staple and co-staple root crop for millions of the rural people in Africa. Recently, it has been demonstrated to be of human health importance by combating vitamin A deficiency. This paper is a summary review of recent findings on the orange-fleshed sweetpotato (OFSP) farmer varieties (FV) from East Africa (EA) and their potential contribution to combat vitamin A deficiency (VAD) in Africa. Between 2000 and 2006, scientists from East and Central Africa collected several OFSP varieties from farmers' fields together with the white- and creamfleshed sweetpotato (WFSP) farmer varieties. Subsequent characterization studies using selected EA and exotic germplasm revealed critical findings for the future use of OFSP FV in Africa. Overall, molecular characterization showed that EA germplasm is distinct from non-African germplasm. It also showed that OFSP FV and WFSP FV from EA are very closely related. The two findings address suspicions that OFSP FV are of exotic origin. The OFSP FV differed from exotic OFSP on root dry matter (DM), starch and sucrose properties. Whereas the exotic OFSP are characteristically 'sweet and moist' (DM ≈ 25.0%, starch ≈50.0% and sucrose ≈ 10.3%), OFSP FV had characteristically high DM (≈33.0%), high starch (≈ 65.0%) and similar to the WFSP FV. It is these qualities that make sweetpotato a staple crop in Africa. However, root â-carotene content (BC) of some OFSP FV ['Ejumula', 240pmm; 'Carrot C', 259 ppm; 'Mayai', 264 ppm; and 'Zambezi', 233 ppm] nearly equaled that of 'Resisto' (271ppm), one of the popular OFSP cultivars in USA. These were shown to meet ≥400% of recommended daily allowance (RDA) with 250 g serving to a 5-8 year old child Other light orange-fleshed FV like 'ARA244 Shinyanga', 'K-118', 'K-134', 'K-46', 'PAL161', 'Sowola6', 'SRT52', and 'Sudan' had lower root BC than 'Resisto' and were shown to meet between 50-90% RDA of the child. In conclusion, OFSP FV from EA might show similar adaptation to sub- Sahara African environments as their sister WFSP and have a big potential to alleviate VAD. Also, breeding for acceptable high DM and high starch OFSP varieties for African consumers seems possibl

Pre-harvest curing: Effects on skin adhesion, chemical composition and shelf-life of sweetpotato roots under tropical conditions

Excoriation (skinning injury) is a serious post-harvest problem for sweetpotato roots. In industrialized countries, sweetpotatoes are exposed to post-harvest curing to facilitate skin toughening and wound healing. However, in developing regions, such a practice is barely undertaken. Pre-harvest curing (PHC), where sweetpotatoes are subjected to defoliation before harvest, is a potential alternative to post-harvest curing. A field trial was conducted in southern Ethiopia. Roots underwent PHC treatment for 3, 7, 10, and 14 days, with 0 days as a control sample. Skin adhesion and chemical composition (ash, crude fibre, crude protein, dry matter, and starch) of the parenchyma and the periderm were measured. Storage testing at ambient conditions for 30 days was conducted. Skin adhesion among all the treatments was significantly increased. The maximum skin adhesion was observed after 14 days (358.92 mN.m); however after 7 days of PHC, no significant change occurred. Root dry matter and ash content remained unaffected by the treatments. An increase in periderm crude fibre was observed for treatment samples, indicating lignification. Parenchyma crude protein concentration demonstrated a sudden drop in value from the control to 3 days of PHC (5.19 to 2.32%). For successive durations, crude protein started to increase from 3 days, demonstrating an active protein metabolism. Starch, the most important constituent affecting palatability and processing of sweetpotato, was not affected by PHC. Roots subjected to PHC for 10 and 14 days presented a potential for enhancing shelf life by having a significantly lower weight loss after 30 days of storage