Post production: Storage

Hermetic Storage systems

Describe hermetic storage and its advantages.

What is the problem of storage in a tropical climate?

Rice grain absorbs moisture from the air around it. This means that if grain is in contact with the air (e.g. an open storage system) the moisture content (MC) of the grain will eventually become the same as the MC of the surrounding air.

Open storage: The grain absorbs

moisture from the air around it

In many tropical countries, there is often a high relative humidity and high temperature. High humidity and high temperature contribute to high moisture content. This means that in many tropical countries the moisture content is too high to safely store grain in an open storage.

This is why it is much better to store grain in closed storages, sealed off from the air. This is called hermetic storage.

As mentioned above, rice grain absorbs moisture until it reaches an equilibrium with the moisture in the surrounding air.

The final grain moisture content you get in the storage is called the ‘equilibrium moisture content’ or EMC.

Click here if you would like to learn more about EMC.

Stop moisture and pests! Seal the rice hermetically!

What are the advantages of hermetic storage?

Hermetic storage greatly improves grain quality and seed viability because of the following reasons:

The benefits of hermetic or sealed storage:

1. You will keep the original storage moisture content because the grain cannot absorb moisture from outside. This will improve seed viability by 6 to 12 months and increase head rice yields by 10%!

2.You will limit damage caused by pests. There will be no oxygen (air), so any insects inside the storage will quickly die.

3. As the grain is sealed off from the air, animals will not be able to smell any grain. This will greatly reduce attacks from rodents and birds.

Outside air and water can not touch the grain

How do you store hermetically?

Hermetically, or sealed, storage systems put grain in an airtight container such as a drum or a plastic bag that stop air and water getting in to the stored grain from outside.

To store hermetically you can use:
	specially designed PVC containers such as the volcanic cube Price: $900 for a 5 ton cube (expected life of at least 10 years)
	50kg recyclable super bag Price: $0.5-1 per bag (contact IRRI to order)
	locally available containers made from steel, plastic or clay Price: $2-5 per big plastic or iron drum

The size of the hermetic storage systems can go from 3 kilograms to 300 tons. The hermetic storage system can be used for paddy, milled rice, seeds and other cereal crops such as corn and coffee.

Click here to learn the steps to store hermetically.

Keep bags closed and free of air!

A few things to keep in mind:

Opening and closing the containers will give fast re-infestation of some insects such as the lesser grain borer which can pierce plastic liners.

In containers that are only part filled, there might be too much air to control insects.

Large commercial plastic storage can be damaged by rodents if not managed correctly. Pull plastic liners tight and keep a clear space around the containers.

Next lesson

Let's see what pests can damage the grain or seed during storage.