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

Abstract

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.