Long-term Storage of Starch Potato and its Effect on Starch Yield
Lyckeby Starch AB is a farmer-owned company that produces products based on potato
starch. In order to increase their production efficiency and their international competitiveness
the company is investigating the possibilities of keeping their factories open longer. To
achieve this, potato has to be stored for a longer period of time than what is practiced today.
Starch potato is usually stored in large piles covered by straw and plastic, either in the field or
on the farmyard.
The objective was to examine in what way starch yield (starch content*tuber weight) in
three different potato varieties was affected by storage in two different types of storage piles.
The potato was stored for three months in total and starch content and tuber weight were
controlled throughout the period. Stored tubers were also visually examined and prescense of
mechanical damage as well as wet rots and dry rots was recorded. Bacteria and fungi were
isolated and identified.
In general, varietal differences were greater than differences between the storage piles.
Loss of starch yield was greatest during the first weeks of storage, and there was a strong
correlation between presence of mechanical damage on tubers and incidence of wet rots and
dry rots. Several bacteria and fungi were identified and there was a tendency of difference in
bacterial diversity between the different potato varieties, which indicates that the different
varieties select for different bacterial species. In order to minimize the loss of starch yield
during storage it is important to choose good potato varieties and to harvest them at the right
time and under appropriate circumstances in order to avoid mechanical damage