3. Basic concepts in post-harvest storage technology

Transcript

Hi friends, I welcome you for this lecture. In the previous lectures we studied about the various technological components, that have been adapted in dryland agriculture. In the previous lecture we studied about the harvesting and also about the mechanization aspects. What are the improved implements that have to be used in the dryland agriculture? Including harvesting and threshing processes. So after the harvest is over we cannot sell the produce immediately, because of the several reasons. So in that cases the harvest produce has to be kept safely in storage conditions. There are so many factors involved in storing the harvested produce. So in this direction today’s lecture has been designed with respect to basic concepts in post-harvest storage.

So coming to the basic concepts in post-harvest storage technology. Harvesting crops is seasonal but consumption of the food crops is continuous. So the harvesting of crops will be taken up seasonal, while the consumption of food grains will be continuous. So even though the crops are harvested, seasonally; because of the continuous consumption of food grains, there is a need to store the grains. And it is necessary to store the produce for different periods for different reasons. One is marketing, home consumption etc. So harvested produce has to be stored because immediately after the harvest, on threshing we cannot get the marketing opportunities. And in some cases the harvested produce is to be kept stored for the home consumption. So based on these aspects we have to have, a best of the best storage conditions.

Let us study what are those. The estimated post-harvest losses per annum is approximately 10%. Why it is so? We don’t have sophisticated storage conditions. Whenever the crop is harvested, and it is stored, in the post-harvest losses the grains will be damaged. So they will not be in a position to be in a consumption purpose. So the post-harvest losses is in a minimum of 10%. So how it is so. A grain saved is a grain produced. It is essential to produce, preserve and market the grains by retaining their quality and reducing the losses. The grains are unique as they can withstand the transport and have long term storage capacity, thus retaining their quality. Upon harvesting these grains have to be stored, and while storing their quality has to be restored. Their quality has to be maintained for further marketing of the produce. In this direction, the storage aspects are very good, and they assume importance.

The unique feature of the grains are, they are able to withstand long time transport, and also they are able to withstand long term storage. So the uniqueness with the grain coupled with the purpose, with which their quality has to be improved; we have to study the storage conditions. And indeed a grain saved is a grain produced. This is very easy, this is very apt, this is very important because a grain saved is grain produced. If the grain is lost, that grain which has been produced is also lost; and during which so many resources are used, and the use of that resources also doesn’t come into the importance.

Coming to the grain storage. The grain storage is a man-made ecological system, in which living organisms and non-living environment interact with each other. The storage or whichever storage structures used. It’s a man-made structure, ecological system, wherein the living and non-living organisms interact with each other in the storage structure. While interacting with each other, they do some damages. So these damages have to be avoided, so as to produce, quality produce. So when stored the important factors to be considered as,

• Temperature
• Moisture
• Oxygen
• And carbon-di-oxide concentrations.

So these are the factors we have to consider while storing the grains. What may be the temperature. Minimum temperature, maximum temperature, what is the oxygen condition, what is the oxygen content that has to be maintained inside the storage conditions, what are the moisture conditions and also what is the carbon-di-oxide concentration inside the storage structure. So these are the factors which have to be looked into while preserving the seeds for their quality.

So important storage insect pests:- Now coming to apart from storage facilities and criteria to be followed in case of temperature, moisture, carbon-di-oxide concentration. There are some of the factors which are insects. There are storage insects which badly affect the grains and made unconsumptionable in storage. What are those? The important are,

• Rice weevil- which make grains hollow by biting
• Then flour beetle- this is very common in case of milled products
• Saw tooth grain beetle- it feeds on grain of rice and flour
• Then rice moth- it feeds on the broken grains of the grain
• Pule beetle- pulse grains almost hollow and not fit to consume

There are storage insects which finds like the grains as food very much. So they attack the grains. So in a way these insects make the grains unconsumptionable or in some cases unmarketable.

Storage :- So in case of storage, a storage temperature greater than 15° centigrade is ideal for good storage, wherein the rate of respiration of the grain increases with an increase in temperature. So reduction in moisture is the key to longer shelf life of the grain. After the harvest, before the storage, the moisture content of the grains should be brought down to 8%. So when there is lesser moisture in the grain; so there will be less chances of being attacked by the fungus or the insect pest. Whereas in the storage, while they are storing the grains, it is very important to store them at the higher temperatures.

Remember before storage :- So there some of the points which have to be remembered before storage. That is,

• Dry and clean the grain to a lesser moisture content. How it can be known, the lesser moisture content. So you can bite the grain with your teeth. With that action, you can easily tell whether the moisture content has been sufficiently reduced or it has to be still reduced. So we have to check with the grain moisture content.
• Then a hard, smooth and crack free floor is good for drying. While drying, there should not be any cracks on the floor. Because if there are any cracks. Through the cracks the infestation is going to occur. So because of that the crackless floor is good for drying.
• Next, clean and disinfest the storage structure. This is very important, the storage structures are to be maintained very cleanly, and before storage, they have to disinfest with certain chemicals. Why it has to be disinfected? They have to be disinfected to kill the eggs and larva of some of the insects. If we don’t do this operation; disinfestation. Whatever the eggs, whatever the larva of insects are there; they will hatch, and they will attack the grains.
• And also remove the broken grains from the whole grains. This is very important while storing the broken grains should not be stored. Because sometimes they are also sources of infestation. So while storing the grains we have to remove the broken grains.

And in this respect there is a wrong notion that seed quality will improve in the storage aspect. It is not at all. The seed quality does not improve in the storage. So when we store the inferior quality seeds in the storage, those inferior quality seeds; they remain as inferior. They cannot become good quality seeds. So the quality of the seeds cannot be improved in storage structures.

And the good quality seeds are those which,

• Germinate well
• Disease free
• And free from dirt and other plant materials

This is very important. When you store the seeds for the seed purpose in a proper storage condition. Then the good quality seeds which have not been attacked by anything in the storage structures. They germinate well. And crop establishment is very fine. And they are disease free. Sometimes in storage if you cannot infest the storage structures, diseases will attack. These diseases will carry that disease onto the field. When the seed is sown that disease will appear. So the seeds which have been stored in a good condition, they germinate well and they are also free from the diseases.

So I will conclude this topic with the saying that, ‘Don’t waste the food grains. Behind every grain are many hours of hard work of the farmer’. This is very important. Right from the germination up to there are many resources being used to develop a single grain. But due to faulty storage practices, if we lost the grain, then the use of all the resources will go as waste. So in this direction the proper storage structures and basic concepts in storage structures have to be remembered and have to be initiated. With this I am concluding the topic on ‘Post Harvest Basic Concept on Storage Technology’.

Thank You.