Introduction to storage
Purpose of storage
The purpose of any grain storage facility is to provide safe storage conditions for the grain in order to prevent grain loss caused by adverse weather, moisture, rodents, birds, insects and micro-organisms like fungi.
Types of storage facilities
Rice storage facilities take many forms depending on:
1. the quantity of grain to be stored,
2. the purpose of storage, and
3. the location of the store.
In general, it is recommended that rice for food purposes be stored in paddy form (=threshed, unhulled rice) rather than milled rice as the husk provides some protection against insects and helps prevent quality deterioration. However, when rice can be stored as brown rice, 20% less storage capacity will be needed. Brown rice is rice grain with its hulls removed but not polished. Under tropical conditions brown rice has a very short shelf life, approximately two weeks.
Requirements for good storage
The requirements for a good storage system 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 challenges in the humid tropics
Rice grain is hygroscopic and in open storage systems the grain moisture content will eventually equilibrate with the surrounding air at the so called equilibrium moisture content (EMC). High relative humidity and high temperatures typical for the humid tropical climate lead to grains absorbing water in storage and to a high final moisture content.