Some of variables are temperature; moisture; oxygen; storage structure; physical, chemical and biological properties of grain bulks; microorganisms and insects, mites, rodents and birds.
Respiration
Respiration is a means of releasing energy from stored nutrients (mainly carbohydrates) and a consequence of long storage is a loss of weight.
Germination
Deterioration results from loss of weight due to enzymes activity and a loss of quality resulting from excessive enzyme activity in the products of processing.
Biochemical reactions
Deterioration changes in grain lipids may be either oxidative resulting in typical rancid flavors and odors, or hydrolytic, resulting in the production of free fatty acids.
Microbial infestation
During storage they respire and given adequate moisture, temperature and oxygen they grow and reproduce, causing serious deterioration in grain.
Insects and arachnids
Insects that infest stored grains belong to the beetle or moth orders: they include those capable of attacking whole grain and those feed on grain already attacked by other pest.
Initially, the rate of deterioration is slow but as the favorable combinations of variables are set and the storage period is prolonged, a very high loss in grain quality and quantity occurs.
Deterioration of grain during storage
