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We have reviewed the various stages of the post-harvest system of specific agricultural commodities.
But our study would not be complete without some pointers on the marketing of these commodities.
In approaching the subject of preparation for sale, it is desirable to show the importance of the quality and packaging in marketing.
The sale of products generally depends on the economic laws of supply and demand. Thus, when products are sold the needs of both buyers and sellers must be met.
Particularly if they are also the producers, the sellers ask to receive a "fair price", especially in relation to production costs, while the buyers agree to pay a "fair price" on condition that the product correspond to their technological and commercial needs.
Such needs may vary in respect to quality, which may be evaluated differently by the potential buyers.
For example, storage corporation managers pay particular attention to the condition of grain, with the objective of ensuring good and lasting conservation, while the managers of processing industries stress the evaluation of its technological quality as it relates to the end-products they want to obtain (oils, flours, etc.).
Merchants, but especially buyers, consider above all the appearance, the smell, and the taste of products. In fact, the quality of products at the time of sale mainly depends on the following factors:
Moisture content
As we have shown above, high grain moisture content implies an increased risk of losses through the development of insects and moulds during storage.
Moulds in particular, beyond the fact that they change the smell, taste and colour of the grain, can make the products unfit for human or animal consumption by producing dangerous toxins (mycotoxins).
In addition to these technical aspects, economic factors enter into the price of products that are sold damp.
Thus damp grain that continues to dry out during warehousing causes a weight loss that amounts to a loss of money in subsequent commercial transactions.
At the time of sale, therefore, differentiated prices must be established according to the moisture content of products, as much in order to acknowledge the efforts of the sellers, or to encourage them to dry their products better, as to give a guarantee to the buyers.
Adulteration and contamination
Product adulteration consists of the presence of any foreign body (sand, stones, stems, leaves, etc.), owing either to accidents or to deliberate and fraudulent acts.
The presence of impurities not only has a negative influence on quality and conservation, it also creates disagreeable surprises economically, if the impurities are bought at the price of the grain.
In order to protect the buyers' interests and to encourage the sellers to clean their products carefully before selling them, differential price scales must be established according to the proportion of impurities in the batches.
This is obviously possible only where precise standards establish the applicable tolerance limits and potential price reductions, according to the proportion of impurities mixed with the products.
In addition, standards must be determined on and enforced for marketing restrictions for potentially contaminated products. Contamination means the presence of residues of undesirable substances which have come into contact with products and have altered their smell or taste, or made them toxic (e.g. insecticides).
Infestation
At the time of purchase, commodities should be completely free of any form of insect infestation.
Indeed the presence of insects can seriously affect storage. Weight-loss, loss of nutrients, bad taste or bad smell are only a few of the harmful effects brought about by the presence of insects. Unfortunately, their action is often invisible.
At the time of purchase, therefore, a careful and thorough check must be made to detect any form or trace of infestation.
So that commercial transactions can proceed properly and to the complete satisfaction of both sellers and buyers, realistic and practical legal standards should be adopted that clearly stipulate product quality, methods of ascertaining it, and marketing standards.
Application of such norms is obviously conditioned by the degree of staff training for workers concerned with quality-control and by the availability of specific equipment.
For foreign trade, where precise international standards do not exist, those obtaining in the countries to which exports are sent can be applied.
For domestic trade, on the other hand, every country may have radically different norms, depending on the specifics of the agricultural commodity quite apart from the eating habits specific to each population.
In any case, such standards should take the following factors into consideration:
- moisture content,
- presence of live insects,
- proportion of damaged grain (germinated, mouldy, discoloured, etc.),
- proportion of broken grains,
- proportion of foreign grains,
- presence of poisonous substances,
- presence of commercially questionable odours,
- technological yields (e.g. for paddy),
- percentage of fat (e.g. for peanuts and sunflower seeds),
- acidity rate of the fat;
These standards should also cover packaging.
Deterioration and losses of products, during transport and storage, depend upon a series of physical, chemical, biological and human factors.
Proper packaging is an important element in reducing losses, especially in the tropics, climate considerably increases the risks of grain deterioration.
The main functions of packaging are:
There are various types of packaging for agricultural commodities, appropriate to the product's characteristics and to the marketing system.
Woven bags made of plant or plastic fibres are the usual type used for grain.
Rather reasonably-priced bags which still fulfil the functions described above can normally be made from such fibres.
The choice of the type of bag should take into account not only its inherent toughness and resistance to humidity, sunlight and pests but also the type of handling anticipated.
Plant-fibre bags
The plant fibres used for making bags are: jute, cotton, and sisal.
The jute bag is the most widely used in the world; indeed, it combines good resistance capacities with a relatively moderate cost.
It can be reused several times since it has good inherent toughness which reduces the risks of tearing; in addition, it protects the grain effectively from sunlight.
On the other hand, it is a relatively heavy fibre with a coarse texture inappropriate for small-size grains. Furthermore, jute easily absorbs humidity and offers little resistance to the attacks of insects and rodents.
To partially offset the disadvantages of humidity absorption, the bags can be lined with plastic or, if necessary, covered with waterproof tarpaulins.
Handling jute bags is easy because the material is not slippery: thus, fairly high stacks can be erected.
The cotton bag is still used for packaging products that have acquired some added value in processing, such as flours or sugar.
Actually its features are practically the same as those of jute, except that the cotton bag is lighter, harder to sew, and more costly.
The sisal bag is rougher than the other plant-fibre bags and is now hardly used except in countries that produce sisal (Mexico, Brazil and some African countries). Its features are comparable to those of jute bags.
Paper bags are more vulnerable and require more delicate handling. They offer very little protection against humidity and insects, and must be stored under good conditions. They are used especially for packaging seeds.
As for the other plant fibres, hemp and linen, they are virtually no longer used for bags because of their high costs.
Plastic-fibre bags
These bags can be made entirely of plastic (polythene), or of mixed fabrics (plant fibre and plastic fibre).
Today, polythene bags are widely used for packaging grain and they seriously rival the traditional jute bag.
These bags have the advantage of being extremely resistant, rot-proof, and impermeable to fats.
However, they must be treated in order to resist sunlight, since polythene deteriorates when exposed to light. With good treatment, a polythene bag can be reused for six to 12 months.
They cost more than jute bags and they are harder to handle because their surface is very slippery, and so they cannot be stacked very high.
Size of bags
Whether they are made of plant or plastic fibres, the capacity of the bags is generally 50 kg (100 x 55 cm or 100 x 60 cm). In several countries, however, capacity may reach nearly 100 kg, which makes for difficult handling.
Thus, to simplify the reception and delivery of bagged grain, it would seem desirable to standardize the capacities and sizes of these bags.
| GRAIN | NORMAL WEIGHT |
| Paddy | 64 kg |
| Milled rice | 45-100 kg |
| Maize, sorghum, beans, wheat, millet | 90 kg |
| Groundnuts, in shell | 29-45 kg |
| Groundnuts, shelled | 74-84 kg |
| Soybeans | 65 kg |
| Cottonseed | 50 kg |
| Cocoa beans | 60-90 kg |
| Coffee beans | 60-65 kg |
| Various flours | 45 kg |
Indicatively, the above table shows the weights considered normal for a bag of grain.