Grain is liable to damage by heating, infestation, sweat and contact with water. When grain gets wet, growth immediately starts not only in the grain itself, but in the mold spores, yeast cells and bacteria, which are always present, causing respectively germination, fermentation and putrefaction. Treatment for water damage is somewhat theoretical for the reason that obstruction to its practical application is the necessity to apply treatment before deterioration sets in, and this is usually impossible, but when the condition of the grain is such that the cost of drying would be justified by the result, this is the only manner in which damage of this nature can be minimized.
Contamination by water may cause heating and deterioration of the grain but such heating may also be due to inherent vice, particularly if the grain is too green when shipped.
Grain may also be subject to an increase in weight if the conditions of stowage, storage, etc., are such that grain shipped dry can absorb moisture.
Infestation can arise in a vessel having carried infested cargo on a previous voyage, but it can also be inherent in the grain itself. During growth, the egg of the weevil may be deposited and sealed in the grain so that fumigation does not affect any unhatched eggs. Lack of ventilation, causing high temperatures in the stowage will produce infestation which was not apparent at the time of loading. Weevil in such grain may cause some loss of weight, although it is not possible to determine a general percentage. Weevil impairs the quality, especially in the case of maize used for the manufacture of breakfast cereals. Heating can be caused in dry materials solely due to the activity of insects and not in any way connected with water damage. As a result of the feeding of the insects, together with their breathing in of oxygen from the air, the gas carbon dioxide and water vapor pass out into the air. In the process heat is produced and the temperature of the commodity rises. This may sometimes be noted in bulk grain where a "hot spot" occurs as the result of insect attack. The higher the temperature the more active are the insects in breaking down the food material into carbon dioxide and water vapor and more heat is produced. This may continue until the temperature reached is harmful to the insects and they move outwards from the "hot spot" to form others around the first. Thus the damage and the heating become widespread in the commodity. So far as insects are concerned, this is intimately connected with heating. When heating within a bulk of a commodity takes place, due to insect activity, this causes air convection currents which carry water vapor upwards from the hot spot. This condenses in the cooler surface layer, thus raising its moisture content. This process may be carried far enough to cause the growth of molds and bacteria and, in the case of grain, to cause sprouting. This type of water damage is essentially a surface phenomenon and is confined to the top few inches of a stack or bulk.
Delay in transit may of itself give rise to heating and so cause the grain to have the appearance of damage arising out of insufficient ventilation, but this condition may have arisen entirely as a result of delay, even though the ventilation requirements have been perfectly satisfactory and not restricted during the voyage.
Grain in process of fermenting may give the appearance of having been in contact with oil, especially by reason of the odor.
Damaged grain should be disposed of as quickly as possible to avoid further deterioration.
A simple test for loss of germination is to place a handful of grain into a glass of water; the sound grain will remain on top and the remainder settle at the bottom of the glass.
- Commodity Name:
GRAIN (Barley, Maize, Oats, Sorghum, Wheat)