|Moulds are the most important microbes associated with cereals during growth, harvest, storage and shipping. They are divided into two groups:|
- field fungi which cause disease in the growing plants
- storage fungi which can spoil the dried grains.
Field fungi need plenty of moisture for active growth, but storage fungi such as Penicillium and Aspergillus can grow with much less. Fungal spores get into the harvested crop from processing equipment and dust in the environment.
Good storage conditions are the key to keeping rice fresh as the spores only germinate if the moisture, temperature and oxygen levels are just right. Moulds cannot grow in rice grains kept at below 14% moisture. Warmth also encourages fungal growth.
Spoiled rice grains can be discoloured, smell "off" and lose their goodness. Once they have started to break down, a wide range of other microbes complete the process of decay.