Agriculture Reference
In-Depth Information
of water loss (Burton, 1966); this indicates that
the resistance to water movement through the
epidermis of sprouts is much less than the resist-
ance of the periderm.
Stored tubers must be managed to prevent
sprouting if tuber quality and grower profitabil-
ity are to be maintained. For fresh market pota-
toes, sprouting can be reduced through the use
of cold storage temperatures. Storing tubers at
3-
4°C maintains dormancy for an extended
period and slows sprout growth after dormancy
is lost (Wiltshire and Cobb, 1996). This method
is less desirable for tubers intended for process-
ing, as it is likely to result in dark-colored fries
and chips due to CIS. Moreover, low-temperature
storage is often insufficient to prevent sprouting
of cultivars that have short dormancy, or for
tubers stored for long periods of time. With care-
ful cultivar selection, cold storage can be expected
to be an effective means of sprout control for
several months.
times during the storage season to maintain effi-
cacy. Other natural products approved for use as
a potato sprout inhibitor are substituted naph-
thalenes and hydrogen peroxide. Both require
multiple applications to achieve full season
sprout control.
Synthetic sprout inhibitors have been used
for many years. In most growing regions, chlo-
ropropam (CIPC, isopropyl N-(
3-
chlorphenyl)
carbamate), has replaced maleic hydrazide as
the preferred sprout inhibitor. CIPC interferes
with mitotic cell division and must therefore be
applied after wound healing is complete. In ven-
tilated potato storages, CIPC is applied through
the storage ventilation system as a fog. In many
cases, a single application is sufficient for sea-
son-long control of sprouting. Although used
most often in modern potato storages, CIPC is
also effective at inhibiting sprout growth and
maintaining tuber quality when used in small-
scale heaps and pits (Mehta
et al
., 2010). Health
concerns related to CIPC residues on potato led
to the imposition of maximum residue levels of
10
mg kg
-
1
in Europe and
30
mg kg
-
1
in the USA
(Kleinkopf
et al
., 2003; EFSA, 2012).
Sprout inhibitors
Chemical or physical sprout control is necessary
for long-term storage of fresh market potatoes,
and for chip and fry processing potatoes that will
be stored at
9-
13°C for more than a few weeks.
A wide variety of materials are available for
sprout control. The suitability of each depends
on customer requirements and product perform-
ance needs. Where tubers must be free of chem-
ical residues when sold, ethylene can be used as
a sprout inhibitor. Ethylene is mixed with the
storage air to a concentration of
4
µl l
-
1
or more
(Daniels-Lake
et al
., 2005a). When used with
processing potatoes, initial ethylene concentra-
tions are applied at low rates and then increased
slowly over several weeks (Daniels-Lake
et al
.,
2007). This minimizes the effect of ethylene on
reducing sugar accumulation and fried product
darkening (Prange
et al
., 1998). Another form
of residue-free sprout control is irradiation with
high-energy electrons (Kleinkopf
et al
., 2003).
Several sprout inhibitors have been pro-
duced from natural products and are appropri-
ate for use on organic potatoes, including clove
oil, caraway oil, mint oil, and others (Vaughn
and Spencer, 1993; Kleinkopf
et al
., 2003). Most
of these products volatilize slowly from tubers
during storage and must be reapplied several
15.8
Potato Storage Management
Summary
Successful storage management results in main-
tenance of stored crop quality, and in many
cases, an increase in crop value. Achieving this
requires planning and attention to detail in how
activities at harvest and in storage are con-
ducted. Below are guidelines for the manage-
ment of potatoes in bulk storage. These are
meant to illustrate the general approach toward
potato storage as practiced in the developed
world. Specific details for tuber management will
necessarily vary by growing region, yearly cli-
mate differences, and experience with individual
storage types.
Guidelines for storage of potatoes
in bulk bins
•
Sanitize storage bins and cool them to pre-
conditioning temperature. Humidify to ~93%
RH prior to harvest.
