Effect of drying and storage on the content of provitamin A of orange fleshed sweet potato (Ipomoa batatas): direct sun radiations do not have significant impact

[Introduction] Sweetpotato is an important crop that is widely consumed in sub-Saharan Africa. Sun drying of sweetpotatoes is a traditional practice: after drying on rocks crushed or sliced dried sweetpotato are stored in granaries; re-hydrated and boiled to be eaten like fresh roots, or milled into flour to make porridge. Orange fleshed sweetpotato is being promoted in Africa to tackle vitamin A deficiency. There are inconsistent reports on the effect of sun-drying on pro-vitamin A retention. High losses have been reported which may be associated with the unsaturated instable provitamin A carotenoids easily degraded by light, oxygen and heat (Rodriguez Amaya 1997). This poster describes work to understand the effects of sun/solar drying and storage on pro-vitamin A retention

Understanding losses of provitamin A after drying and storage of orange-fleshed sweetpotato (Ipomea batatas)

[Draft Abstract - from Oral Presentation] Biofortified orange-fleshed sweet potato (OFSP) is being promoted to tackle vitamin A deficiency, a serious public health problem affecting children and pregnant/lactating women in sub-Saharan Africa. The aim of the study was to quantify and understand the factors influencing provitamin A losses in OFSP dried chips. Losses were determined after drying and storage. A preliminary pilot-scale study demonstrated that carotenoid levels were not significantly different after either solar or sun drying. Field conditions using locally-promoted varieties in Uganda and Mozambique showed losses associated with drying were less than 40%. Flour made from OFSP could therefore be a significant source of provitamin A. In contrast, storage of chips at room temperature in Uganda for four months resulted in high losses of pro-vitamin A (ca. 70% loss from the initial dried product). Low-cost pretreatments, such as blanching, antioxidants and salting, did not improve carotenoid retention during storage. To understand the cause of the losses, dried sweet potato chips were stored under controlled conditions of temperature (10; 20; 30; or 40ºC), aw (0.1; 0.3; 0.5 or 0.7) and oxygen (0 [under nitrogen]; 2.5; 10 or 21% [air]). Losses in provitamin A were the least during storage at the lowest temperature and oxygen level and at the highest humidity level. Enzymatic catabolism of beta-carotene in the flour was considered unlikely because of low peroxidase activities at low water activities and the loss of peroxidase activity during storage

Effect of hot air, solar and sun drying treatments on provitamin A retention in orange-fleshed sweetpotato

Different drying treatments, cross flow, greenhouse solar, and open air-sun, were applied to an American orange-fleshed sweetpotato variety. Trans-β-carotene losses in flour made from dried chips varied between 16% and 34% in all treatments. Hot air cross flow drying retained significantly more provitamin A than sun drying. Solar and sun drying were not significantly different in terms of provitamin A retention. The shape of the sweetpotato pieces (chip or crimped slice) influenced provitamin A retention during sun drying; crimped slices retained more provitamin A. Other minor provitamin A compounds in fresh sweetpotato included 13-cis- and 9-cis-β-carotene and β-carotene 5,6 epoxide. No significant increase in the cis-isomers was observed after drying. Vitamin A activity in flours was found to be greater than 1,500 RE (β-carotene:retinol; 13:1) per 100 g including in sun-dried samples. Flour from orange-fleshed sweetpotato therefore has potential as a significant source of provitamin A

Effect of hot air, solar and sun drying treatments on protavitamin A retention in orange-fleshed sweetpotato

Different drying treatments, cross flow, greenhouse solar, and open-air sun, were applied to an American orange-fleshed sweetpotato variety. Trans-?-carotene losses in flour made from dried chips varied between 16 and 34% in all treatments. Hot air cross flow drying retained significantly more provitamin A than sun drying. Solar and sun drying were not significantly different in terms of provitamin A retention. The shape of the sweetpotato pieces (chip or crimped slice) influenced provitamin A retention during sun-drying; crimped slices retained more provitamin A. Other minor provitamin A compounds in fresh sweetpotato included 13-cis and 9-cis-?-carotene and ?-carotene 5,6-epoxide. No significant increase in the cis-isomers was observed after drying