After
harvesting, the storage roots are sorted to remove the diseased and
damaged ones as well as to separate them into different sizes. Root
classification into different grades vary among places but generally, this
practice is done to separate the rejects from the marketable roots. The
reject is composed of oversized, undersized, and damaged roots. The rejected
roots can be sold at lower price, kept for home use, fed to the animals, given
or thrown away. The final grading is done by the assembler/wholesaler.
Roots are sometimes classified into sizes based on their
diameter but this was found to be accurate only when roots are roundish in
shape. When roots are elliptical to cylindrical in shape or otherwise irregular,
a classification based on weight is better.
Roots are cleaned by washing or by simply removing the
adhering soil without washing. Washing is done depending on market
requirement.
Curing, a recommended postharvest practice to promote
hardening of the skin in preparation for a long storage period or rough
handling, is not commonly practised in areas where roots are immediately sold
after harvesting.
The packaging materials for sweetpotato differ among places
and countries. In some Asian countries wooden crates/boxes, large baskets (made
of rattan or bamboo), synthetic sacks and jute or burlap sacks are used.
Comparison of roots transported in three types of containers
showed that storage roots transported in sacks had the least damage during
transport for four hours. During longer transport period, however, roots in
wooden crates had the least damage.
Cultivars differ in storability. Some can be stored beyond 60
days after harvest (DAH) and even until 90 DAH without losing marketability
while others show shriveling, sprouting and decay even at less than 30 DAH
depending on the storage condition. Comparison of the storability of some
cultivars under upland and postrice Philippine conditions showed that roots
stored in the upland had lower rotting, sprouting and shriveling (Amante, et.
al,1992). Lower temperature and higher relative humidity characterised this
condition. The data also showed cultivar differences in storability.
