Preservation Of High Moisture Grains By Organic Acids

Over the last century there have been significant advances in the preservation of grains. Traditional methods included field drying and artificial drying which require a considerable initial investment. The preservation of high moisture grains by chemical treatment is an alternative method that was introduced about a decade ago. This preservation method has many benefits and is now considered an effective and affordable tool.

Over the centuries there has been many techniques tried and tested to preserve grains. Moulds and bacteria are the main culprits for spoiling grain, along with rodents. Moulds are common contaminants in animal feeds. Conditions that favour moulds are high moisture levels, warm temperatures, the presence of oxygen, and prolonged storage time. Moulds are toxigenic and produce mycotoxins and consume valuable feed nutrients.

While preservation of grain grown for human consumption is very much controlled, grain that is used for livestock has more options when it comes to preservation techniques. Preserving high moisture grains by chemical treatment is a method considered suitable for livestock grain. The most suitable treatment is short-chain volatile fatty acids, such as propionic, acetic, and isobutyric. These are non-toxic to mammals and produce no mutagenic, carcinogenic, or teratogenic properties. Research has shown that these organic acids do not affect the nutritional value of grain and do not transfer residues to meat, milk poultry and eggs.

Applying appropriate organic acids at proper rates, based on moisture level of the grain and duration of the storage, reduces the PH of the grain to near 4. This inhibits development of a wide range of microorganisms, such as mould, yeast and bacteria, which are responsible for spoilage. Besides extending the shelf life, organic acids also maintain the nutritional value of the grain.

Harvesting high moisture grain and preserving it by chemical treatment enables earlier harvesting by 2-3 weeks which may reduce labour and weather problems with harvest. Organic acids also require less capital investment than other storage methods, particularly compared to drying. Treated grain can also be transported longer distances without risk of spoilage. However, as stated earlier, organic acids should only be used in grains preserved for livestock, and unfortunately they do not repel rodents.

Although chemical treatment is an effective and affordable tool to preserve grain, acids are corrosive so they must be handled carefully and with the correct equipment. Make sure you use the correct chemical measuring device and chemical resistant drum pumps when dispensing any acid liquid in an agricultural or horticultural environment.