Drying is the process that reduces grain moisture content to a safe level for storage. It is the most critical operation after harvesting a rice crop. Delays in drying, incomplete drying or ineffective drying will reduce grain quality and result in losses.
Storing grain is done to reduce grain loss to weather, moisture, rodents, birds, insects and micro-organisms. Usually rice should be stored in paddy form rather than milled rice as the husk provides some protection against insects. In the International Rice Genebank where rice seed from more than 118,000 different types of rice is conserved, rice seed is kept in vacuum packed, freezers at -18 °C, where they can remain viable for 100 years.
Rice storage facilities take many forms depending on the quantity of grain to be stored, the purpose of storage, and the location of the store.
A good storage system should include:
- protection from insects, rodents and birds by allowing proper storage hygiene
- ease of loading and unloading
- efficient use of space
- ease of maintenance and management
- prevention of moisture re-entering the grain after drying
- specific solutions to meet the challenges of storing rice in the humid tropics.
Milling is a crucial step in post-production of rice. The basic objective of a rice milling system is to remove the husk, and produce an edible, rice grain that is sufficiently milled and free of impurities. If only the husk is removed then ‘brown’ rice is the product. If the rice is further milled or polished then the bran layer is removed to reveal ‘white’ rice.
Depending on the requirements of the customer, the rice should have a minimum of broken grains.
A rice milling system can be a simple one-or two-step process, or a multi-stage process. Depending on whether the the paddy is milled in the village for local consumption or for the marketing rice milling systems can be classified into the categories village rice mills and commercial mills.
Packaging and transport to point of sale
Once milled, rice is packed and transported to point of sale, which may be local or international.