Nutritional significance
Processing
Products
The suitability for small-scale production
Staple foods are those which are eaten regularly as part of the daily diet and nearly always include cereals or pulses. Rice, for example, is widely consumed in Asia, whereas beans and maize are more popular in many African, Latin American and Caribbean countries.
As a result of importation and price subsidies in some countries, wheat has grown in popularity and the demand for wheat-based products such as bread and pasta has increased. Consequently some indigenous grains are not being used to their full potential.
Owing to a low moisture content, cereals and pulses are relatively stable during storage and processing is not so much for preservation but rather to change the eating quality and add variety to the diet.
Both cereals and pulses are nutritionally important since they usually provide the bulk of the diet. They are also a relatively cheap source of energy, protein, and important vitamins and minerals.
Some businesses are set up to clean and package wholegrains and pulses. These businesses can be successful as there is very little need for equipment and consequently the required capital investment is relatively low. However, with all business ventures, a clear demand for the product must be identified.
Wholegrains are normally processed before being used as an ingredient to produce a range of products. Processing techniques include puffing, flaking and milling. (This chapter does not cover production of drinks made from cereals. For details please refer to the Beverages chapter.)
Puffed products
Puffed grains and pulses are often used as ingredients in breakfast foods or as a snack food. During puffing, grains are exposed to a very high steam pressure, which when rapidly released causes the grains to burst open. The equipment necessary for puffing involves the use of high pressures and steam. In view of this the operator must take special care when handling the equipment, in order to prevent accidents. Puffed grains and pulses may be further processed by toasting, coating, or mixing with other ingredients.
Flaked products
Before flaking, grains and pulses are softened by being partially cooked in steam. They are then pressed or rolled into flakes which are subsequently dried. Such partially-cooked cereals may be used as quick-cooking or ready-to-eat foods.
Both flaked and puffed grains are eaten crisp and need to be packaged in moisture-proof containers. The moisture content must be below 7 per cent, otherwise the product becomes soggy and tough.
Milled products
Grains and pulses are milled to produce flours which are used to produce many types of food. Three main types of mill are available:
· Plate mill
· Roller mill
· Hammer mill.
The choice of mill will depend on the raw material and also on the envisaged scale of production. Section 41.0 of this book illustrates a range of different mills, but for details of the milling process and in-depth guidelines relating to choice of machinery, it is suggested that reference be made to the 1992 edition of Tools For Agriculture.
Flours and flakes can be used as starting materials for the following types of product.
Doughs and batters
Doughs and batters are made from a combination of flour, fat, and water or milk. By including other ingredients such as sugar, yeast, fruit, and nuts there is plenty of scope to create a variety of products.
The major difference between doughs and batters is that the moisture content of a dough is lower than that of a batter, and consequently doughs have a heavier consistency and can be moulded into many shapes. Both doughs and batters can be fermented to produce many products. For example fermented maize products such as 'Kenkey' in Ghana and 'Bagone' in Botswana are considered to be staple foodstuffs.
The production of batters and doughs involves mixing ingredients together to a smooth and uniform consistency. This can be done manually or with a powered mixer. The type of powered mixer required will depend upon the product being prepared. For example, a batter will need a balloon whisk-type mixer whereas a dough will require a hook-type mixer. There are general purpose mixers available for use on a small scale, which have attachments for both products.
There are various ways in which doughs and batters may be subsequently processed.
Extrusion
Extrusion involves forcing food through a hole (or die) to produce strands or other desired shapes. Once the food has been extruded it is likely to undergo a series of further processes such as frying, boiling, or drying.
Examples of extruded doughs include snack foods such as bombay mix and a wide variety of pasta products and noodles. The latter are increasingly becoming part of the daily diet for many people around the world since they are quick and easy to cook, offer convenience, and require less fuel for cooking. A further advantage of these products is that if dried, they can be stored for a long time.
The table below outlines stages in production for rice noodles. Similar processes are used for pasta and snack foods using appropriate ingredients:
Production stages for rice noodles
|
Ingredients |
Processing stage |
Equipment |
Section reference |
|
Rice flour, water |
Mix ingredients to a dough |
Powered mixer (optional) |
43.2 |
|
|
Roll into thin sheets of dough |
Rolling equipment |
59.0 |
|
|
Cut into strands |
Cutting equipment |
17.1 |
|
|
Extrude |
Extruder |
27.0 |
|
|
Steam |
Steam blancher |
01.0 |
|
|
Dry |
Solar dryer |
23.1 |
|
Fuel-fired dryer |
23.2 |
||
|
Electric dryer |
23.3 |
||
|
|
Pack |
Polythene sealing machine |
47.1 |
Noodles can be made from a range of flours including rice, wheat, maize, and potato. The dough can be processed in one of two ways, either rolled out into thin sheets of dough and cut into strands, or extruded.
The strands are then steamed, and may either be eaten fresh, or processed further by drying. Drying can be achieved using either a solar or a fuel-fired dryer. It is possible to dry the noodles in the sun, but the quality of the finished product is likely to be lower. Packaging requirements for dried noodles include a moisture-proof package (e.g. polythene) and an outer carton/box to prevent crushing.
Baking
A wide assortment of baked products can be produced, including cakes, biscuits, and leavened bread. For details of processing and equipment requirements, please refer to the Baked Goods chapter.
A further group of products include a range of unleavened breads which are baked using a hotplate, often known as a griddle. Doughs are usually rolled to shape, (e.g. chapattis, roti, and tortilla), whereas batters are usually dropped onto the griddle using a spoon (e.g. pancakes and 'Kisera', a Sudanese product made from sorghum).
The table opposite outlines the stages in the production of tortilla, a bread widely consumed in Latin America.
Production stages for tortilla
|
Ingredients |
Processing stage |
Equipment |
Section reference |
|
Maize, lime* |
Boil grains in water and lime (until the grains can be peeled by hand) |
Boiling pan |
48.0 |
|
|
Wash the maize |
Clean potable water |
|
|
|
Mill grains with the addition of water |
Plate mill |
41.1 |
|
|
Mix to a dough with water |
Powered mixer (optional) |
43 2 |
|
|
Shape |
Rolling equipment |
59.0 |
|
|
Fry on a hotplate |
Hotplate |
36.0 |
|
|
Consume immediately or pack |
Heat sealing machine |
47.1 |
*The lime involved is not the fruit but the chemical.
Frying
Frying involves cooking food in hot oil. Doughnuts are an example of a fried dough which is consumed as a snack food.
It is important to make sure that the temperature of the oil is correct. If the temperature is too low then the level of fat absorption in the doughnut will be too high, leading to a greasy product. If, on the other hand, the temperature is too high, then it will become necessary to remove the doughnuts before they are cooked, in order to prevent over-browning.
Production stages for doughnuts
|
Ingredients |
Processing stage |
Equipment |
Section reference |
|
Flour, fat, yeast, sugar |
Mix dough |
Mixer |
43.2 |
|
|
Shape |
|
|
|
Jam |
Add jam if necessary |
|
|
|
|
Place on oiled tray and prove |
Proving cabinet |
|
|
Oil |
Fry |
Deep-fat fryer |
33.0 |
|
|
Drain |
|
|
|
Sugar |
Roll in sugar |
|
|
|
|
Pack |
Polypropylene or polythene bags if necessary |
47.1 |
The shelf-life of fried foods is mostly determined by the moisture content after frying. For example, doughnuts have a relatively short shelf-life owing to moisture and oil migration during storage. Packaging is therefore not necessary, except to keep the product clean.
Porridge-type products
Flours and flakes are often cooked with water to produce a porridge. These porridges are prepared in the home as a main meal, and their consumption is prominent in many parts of Africa (e.g. foodstuffs such as 'banku' and 'ugali' made from maize and consumed in Western and Eastern Africa respectively).
Weaning foods are a combination of cereals and pulses prepared as a mixture of flours and flakes. These foods are designed to be made into a porridge by adding water or milk. Many weaning foods are made by multinational manufacturers on a large scale. However, it is possible to produce a weaning food on a small scale by:
· preparing the correct combination of raw materials
· roasting the mixture of cereals and pulses
· milling using a hammer mill
· packing as a dry mix.
Such mixtures can then be reconstituted in the home and mixed to a porridge-like consistency with water. It is vital that nutritional advice is sought to ensure that the mixture is nutritionally balanced, containing sufficient energy, protein, and other nutrients which will maintain the health and growth of the child. Such foods are vital since it is in this transition period from the breast to the family pot that the child is most likely to suffer from protein-energy malnutrition and other nutritional deficiency diseases.
It is possible to make many cereal and pulse-based products on a small scale using domestic scale equipment. Some products such as pasta require special pieces of equipment, but the majority are not overly expensive and are affordable by many small-scale producers.
The technical knowledge required for many cereal and pulse-based products is quite low, but consistent quality and a degree of flair and skill is needed to produce a marketable product.
