methods can remove dockage, external
insects, weed seeds, and foreign materials,
and can improve its storability. Furthermore,
as grain is being stored, chemical grain pro-
tectants can be applied to provide residual
protection against insects.
Grain may be fumigated through the use
of a modified atmosphere, such as carbon
dioxide and nitrogen. Fumigation by inert
gases is receiving more attention because of
increased restrictions on the use of chemi-
cals. Although inert atmospheres do not rep-
resent a residual hazard, the environment in
a storage bin with an inert gas can be as
deadly to humans as if it contained a lethal
concentration of a chemical fumigant. Insect
feeding and reproduction can be reduced in
temperate regions if storage bins are
equipped with aeration systems.
Control of dust in handling and storage of
low-moisture foods can improve housekeep-
ing and pest control. The containment of
dust production reduces deposits on floors,
walls, ledges, overhead objects, and equip-
ment, with a resultant decrease in cleaning
time. Dust control is enhanced through suc-
tion (reduced pressure) on grain handling
equipment such as conveyors, receiving hop-
pers, bucket elevators, and bins, as well as at
points in the handling system where product
is transferred from one piece of equipment
to another (e.g., from spout to conveyor belt,
conveyor to bin, and bin to conveyor).
The application of highly refined oils to
grain as it goes to storage is an effective way
to reduce dust when handling grain. Oil,
which may be added to levels of up to 200
ppm, should be applied to the grain as
closely as possible to the point of discharge
from the transport vehicle to reduce dust
formation and to provide a grain protectant
treatment.
Although the sanitation of root crops,
such as potatoes, during storage is not as
critical as for other foods, storage conditions
must be controlled to prevent Fusarium
tuber rot and bacterial soft rots. Well-venti-
lated storage rooms with concrete floors
have enabled the potato storage industry to
exert adequate control over its product.
According to Troller (1993), 80% to 90% of
the potatoes harvested each year are stored
in such facilities.
The bulk storage of oils and shortenings
normally occurs in large carbon steel or
stainless steel tanks. Thus, appropriate sani-
tation can be attained by proper cleaning of
these containers—washing with a strong
alkaline solution or alkali and detergents
before use. Hygiene conditions can be
enhanced further through the nitrogen blan-
keting of process and deodorized oils. How-
ever, precautions are essential during the
bottling and emptying of unprocessed,
processed, and deodorized oils to prevent
excessive splashing and agitation, which can
potentially promote oxidative deterioration.
Cleaned bulk tanks (especially carbon steel
tanks) should be recoated with oil to seal
them for rust prevention.Pest Control
Since pest management and control is dis-
cussed in Chapter 13, only stored product
insect pests will be discussed here. Stored
product pests are classified into two groups,
based on characteristics of their life cycle.
Internal pests spend most of their life cycle
within a whole seed or kernel of grain and
rarely feed in processed foods. External pests
normally feed on processed foods and spend
most of their lives on milled grains and
grain-based food products. Adults of some
species can utilize nonfood products, espe-
cially pollens and molds.Internal Feeders
WeevilsAdults of rice, maize, and granary
weevils range from 0.3 to 0.6 cm long. Adult
weevils or commonly called snout beetles