Contents - Previous - Next
This is the old United Nations University website. Visit the new site at http://unu.edu
Guidelines for the development of processed and packaged weaning foods
Guidelines for the development of processed and packaged weaning foods
Ricardo Bressani and Luiz G. Elias
Institute of Nutrition of Central America and Panama (INCAP), Guatemala City, Guatemala, Central America
In order to develop and use foods of high nutritional quality, including weaning foods, for home preparation or industrial production, it is necessary to obtain background information on the food systems prevailing in the country, locality, and/or area where the food is to be developed. The food system includes three sectors: food production, storage, and marketing; food availability and food consumption patterns; and the national capacity for food processing.
The information should include different aspects on production, storage, availability, marketing and processing of foods, with emphasis on the basic staples, but not excluding other food items such as oilseeds, animal food products, fruits, vegetables, and other agricultural products likely to be produced. Likewise, information of significant value would be that obtained from food consumption practices, habits and taboos, weaning practices, frequency of intake of particular foods, food preparation, function and forms, and factors that modify the above as a whole and in selected groups of the family. Knowledge on the chemical and nutritional quality of the diet and of its individual components is equally important. Information related to food processing at the industrial level becomes important if a weaning food is to be produced commercially.
There are two approaches to improving nutritional status. One is to fortify a commonly eaten dietary staple (cereal, starchy roots, fruit, food legumes) with essential nutrients that are deficient in the usual diet. The other is to supply a dietary supplement that contains a portion of all essential nutrients to complement the basic diet. If the product is a weaning food, a number of industrial technologies are available to make a high-quality food. However, the socioeconomic characteristics of the target population make it difficult to reach those most in need. It can be achieved, however, through education, demonstrations, provision of incentives, and improvement in the overall socio-economic situation (figure 1).
FIG. 1. Overview of the Components for the Development of Processed Packaged Foods
The Prevailing Food Consumption Pattern
As a first step in the design of weaning foods for home preparation or for industrial production, it is important to know, as quantitatively as possible, the food ingredient composition of the diet consumed by the target population. In general, the bulk of the diet is made by a specially processed cereal grain and a food legume. The cereal grain is often replaced by starchy foods, such as roots and plantain. For the small child, the main food offered is often either the main cereal grain consumed by the rural population or cereal grains known to be well accepted by the child. For example, in Guatemala, small children are given lime-treated corn tortillas or thin gruels made from rice, or bread made from sweet dough. Usually, and as early as two to three months of life, culinary fractions of the second most important food of the rural diet is given, such as the cooking broth of beans. Other food items, if available are included, and range from small amounts of animal food products to green vegetables. This kind of information can be very useful in designing weaning foods to be prepared at home or industrially.
As important as knowing which foods make up the diet is knowledge of food preparation practices at home so that the commercial producer will understand the organoleptic property and flavour acceptable to the consumer. Furthermore, knowledge of home methods may suggest how and when to introduce supplementary foods. An example is the supplementation of lime-treated cooked corn with whole soybeans. Likewise, knowledge of environmental conditions, kinds of water supplies, and cooking facilities provides insights on various properties the weaning food should or should not have. A possible sequence of guidelines on the above would be the following:
1. Carry out dietary surveys to determine the kinds of foods consumed, the amounts ingested, the frequency of consumption, as well as the general characteristics of the diet in terms of its major components, and their availability from the agricultural point of view
2. Attention in the previous guideline should be given to the diet consumed by the specific population group where the food in question is needed.
3. Information is required on the reasons for the dietary practices of the population in relation to food patterns.
4. Knowledge is necessary about the food preparation processes used at the home level.
5. Equally important is understanding of the function of foods in the diet, the flavour preferences, texture, and other factors important in its acceptance.
6. It is also of importance to determine the nutritional quality of the diet from the chemical and biological point of view.
7. Attention must also be given to the cost of the food in relation to what is expected from it; i.e., whether to feel full, to obtain pleasure, to provide strength, or for socio-economic reasons.
8. Special attention should be given, particularly in rural areas, to the sanitary conditions around and in the house and during food preparation. Water supplies must receive particular emphasis.
Availability of Potential Food Materials
Food ingredients for the formulation of high-quality, nutritious foods may come from four sources.
From agricultural production. Food consumption surveys reflect the main agricultural food products of a country and these are usually selected to be ingredients of weaning foods. Availability of the cereal grains is significantly higher than that for other food items, and food legumes are seldom used because they are scarce and costly. However, legumes seem to be more adequate for weaning foods prepared at the home level. Other cereal grains besides the main staple can, however, be used, depending on availability and cost, and production feasibility in the country. Other food products should be considered, particularly those from animal origin, such as milk, and fruits and vegetables. For example, plantain, bananas, and potatoes are not often used, although they offer interesting opportunities.
There are sometimes foods with good potential for use in weaning foods in a country, but because production level is low, they are not readily available and are not used. These products could be promoted. Likewise, high-yielding cereal grain varieties with characteristics that make them unacceptable for direct use could be processed for weaning food development.
Agricultural by-products. Besides the main crops produced, other agricultural products must be considered, in particular those that are better sources of protein, such as the oilseeds. However, these seeds are generally used for their oil, and the residue after processing for oil is not of a quality adequate for human consumption. Some oilseeds, such as soybeans, do not have to be processed industrially in order to be used in the preparation of weaning foods, although they must be processed for consumption.
Other agro-industrial by-products include those from the cereal grain industry, particularly rice and wheat, e.g., broken rice and brans, and they are good sources of nutrients and usually inexpensive.
Intermediary industrial products. Although the byproducts of the agro-industries could be considered intermediary food products, they often lack the quality required for acceptability. The presence of an industrial capacity to produce intermediary food ingredients is very important, and at present the most common is that for wheat flour. This is significant because otherwise an industry set up to make weaning food has to produce all of the ingredients beforehand.
New food sources for a particular country. A variety of new food sources are likely to be available locally or could be locally produced, but because of low productivity, undesirable factors, and lack of knowledge for their production and processing, they have not been tried.
Basic Nutritional Information on Potential Products
The number of products used in the development of weaning foods is relatively small. The cereal grains used have been corn, rice, wheat, and sorghum; food legumes have included common beans, field beans, chickpea and pigeon pea; oilseeds used are mainly soybeans and to a lesser degree, peanut, cottonseed, and sesame; starch-rich foods include cassava, yams, potato, plantain, and banana. Therefore, information should exist on the basic nutritional data for these materials.
Calorie sources. Sources of carbohydrate calories to be used in weaning food formulations include starchy foods, such as cassava, yams, plantain, and bananas that contain little protein. Energy sources with oil and protein include peanuts, soybeans, and sesame seed. These products contain proteins with good amino acid balance, although they are limited in lysine and sulfur amino acids, which must be corrected during formulation. The protein quality and digestibility are high, with values ranging from 80 to 95 per cent.
Protein sources. Because of the amounts used in formulations, cereal grains can be considered to be protein sources, although the percentage of protein is low because of deficiencies in lysine and tryptophan.
The oilseed flours, once the oil or the carbohydrate is removed, are protein sources. In general, the amino acid pattern is similar to that of the original seed, but protein concentration is high (table 1).
Other nutrients. The ingredients used to prepare weaning foods or other products contain other nutrients such as minerals and vitamins, whose content should be determined for better background information before proposing mineral/vitamin supplements. Sometimes, even though specific nutrients are present, they are not totally available to the organism, or other organic components, for example physic acid and tannins, interfere with their biological utilization.
Antiphysiological factors. Most potential weaning food ingredients contain antiphysiological factors. These are often destroyed or inactivated by appropriate processing, and others are, or should be, reduced to acceptable levels. Table 2 indicates the antiphysiological substances of interest in the main products used in the preparation of weaning foods, and shows how they are inactivated or partially removed.
National Industrial Capacity
In programmes designed for the development and production of weaning foods at the industrial level, it is necessary to have a general, and in some cases the specific capacity, that the local food processing industry has in using equipment resources to manufacture a constant supply of foods, and the technical capacity to produce the kinds of weaning food ingredients meeting quality specifications for human consumption. Two approaches are therefore needed: (i) to discover any unused capacity to manufacture ingredients, and (ii) to ensure the technical capacity to produce quality foods.
Storage and processing of cereal grains Two areas are important. One is the national capacity to store grain products without loss of quality from insect attack and fungi.
TABLE 1. Amino Acid Deficiencies in Various Products Used in Weaning Food Preparations
|Whole corn||Lysine - tryptophan||Methionine|
|Degerminated corn||Lysine - tryptophan||Methionine|
|Rice (white)||Lysine - threonine||Methionine|
|Cereal grain by-products|
|Peanut||Lysine - methionine||-|
TABLE 2. Antiphysiological Factors Present in Ingredients for Weaning Foods
|Food legumes||Trypsin inhibitors||Inactivated by heat|
|Haemagglutinin||Inactivated by heat|
|Soybean||Trypsin inhibitor||Inactivated by heat|
|Urease||Inactivated by heat|
|Cottonseed||Gossypol||Reduced during oil extraction|
|Lupine||Alkaloids||Reduced during processing|
In the case of common beans, storage problems often arise in the humid tropics because of lack of adequate storage conditions. Poor facilities result not only in physical losses of grains, but also losses in nutritive value and in organoleptic and cooking characteristics.
The second has to do with the capacity to produce, under sanitary conditions, by-products from cereal grain milling that could be used in weaning food formulations, such as broken rice, rice polishings, wheat and corn germ, and gluten.
Industrial sources of protein. The protein source for most weaning foods is derived from oilseed processing plants, whose primary objective is to produce oil with little regard to the nutritional, organoleptic, and bacteriological quality of the meal, or of the product remaining after oil extraction. Although the industry may have the technical and physical capacity to produce a flour with acceptable quality, often it is not attractive economically. An example of this has been cottonseed flour for human consumption, which requires appropriate processing to meet quality specifications and remove the gossypol.
Relationship between agricultural production and the food industry. This relationship is essential in programmes designed to produce high-quality foods. It exists for some food industries, such as processors of tomatoes and citrus fruit, and for oil production, but not for other high quality foods. Some possible mechanisms to relate agriculture to industry and promote the industrial production of weaning foods is shown in table 3.
DEVELOPMENT OF THE WEANING FOOD CONCEPT
Two avenues are open for the development of weaning foods, applicable at the home level or for industrial production. The first is the enrichment of traditional foods, or supplementation, and the second is the development of a "new food" or high-quality protein foods. For home preparation and for industrial production it is necessary for a country to have an ongoing industry manufacturing the traditional food. For the second, it would be necessary to develop or set up a new industry in most cases, or take advantage of any unused processing capacity of the country
Supplementation of basic staple foods. The rationale behind supplementation of a staple food is that its quality is nutritionally poor because it is deficient in amino acids and other essential nutrients. These deficiencies can be corrected through the addition of small amounts of foods that are rich sources of the nutrients limiting the nutritional utilization of the staple food. The amounts added should be enough to increase changes in nutritional quality without affecting the preparation, functional properties, or organoleptic characteristics of the product. Examples include the addition of soybean protein to corn or wheat for tortilla and bread production, respectively. The nutrients added can be protein and energy as well as minerals and vitamins (table 4). There is often a small increase in protein content and quality associated with protein supplements.
TABLE 3. Mechanisms to Promote the Industrial Production of Weaning Foods
|Mechanism||Raw Material||Intermediary Products||Final Products|
|Promotion of agricultural production||X|
|Financing feasibility studies||X||X|
|Promotion of consumption through education, advertisement, and quality control||X||X|
|Promotion of intermediary consuming Industry||X||X|
TABLE 4. Minimum Amounts (in Per Cent) of Various Supplementary Proteins found to Improve the Nutritional Quality of Cereal Grains and Starchy Foods
|Egg||Casein||Meat||Fish||Soy Protein||Soy Flour||Cottonseed Flour||Yeast||Beans||Milk|
Specific Guidelines for Supplementation
The food selected for supplementation must be the major
component in the usual diet.
Food intended to be supplemented must be produced industrially, although not in the case of home-prepared weaning foods.
Supplementation should be done by adding those nutrients lacking in the particular food, but at levels required to improve the nutritional quality of the whole diet.
If possible, other nutrients not deficient in the particular food but lacking in the diet, should be added.
Processes used at home for the preparation of a selected food should not affect the biological utilization of the added nutrients.
Addition of nutrients must not change flavour, texture, colour, and if possible, not interfere with processing conditions normally used.
The nutritional value of the supplement as well as its efficacy in improving the nutritional value of the diet must be assured by running chemical and biological assays.
The addition of nutrients should not interfere with the efficiency of utilization of other nutrients present in the food itself or in the diet as a whole.
Preparation of the supplement, and if possible that of the supplemented food, must be carried out at an industrial level to assure a homogeneous product.
Chemical and biological quality control tests must be devised and applied periodically in order to guarantee the effectiveness of the supplement, as well as that of the supplemented food.
Processing conditions at the industrial level to prepare the supplement must be constantly monitored in order to maintain desirable chemical, sanitary, and nutritional characteristics.
The cost of the final product must be within a range that the consumer can afford.
Balanced food mixtures. To achieve balance in combining foods, advantage should be taken of the complementary effect of mixing two or three protein sources. A complementary effect takes place when the amino acids limiting the quality of one ingredient are provided by a relative excess of these same amino acids in another ingredient, which results in an increased quality above that of any single ingredient. Table 5 summarizes examples of the concept, using a variety of potential ingredients. The addition of other foods to the mixture to give maximum complementary effect results in improved quality of the diet.
Supplementary mineral and vitamin mixtures. With either approach, the supplementary or complementary method, and for weaning foods, it would seem advisable to add a supplement of minerals and vitamins, which may or may not be based on the diet consumed daily. It is recommended because it implies a more efficient utilization of the weaning food, which itself could induce micronutrient deficiencies if these are not available in the basic rural diet.
Commodity specifications. There is at present no set standard for the chemical composition of weaning foods.
TABLE 5. Optimal Mixture by Weight of Two Ingredients for Weaning Foods
|Cotton seed /yeast||60/40|
Protein content is quite variable (16 to 28 per cent) in current industrially produced weaning foods. Milk could be used as a model. As a rule, low protein content should have a higher quality than required when protein content is greater. Because the amounts to be used are relatively small, and as they will play the role of an only food, or a supplemental food, higher nutrient density is recommended. The commodity should therefore have consistent nutrient content and quality specifications, including bacteriological quality. Likewise, physical characteristics should be considered, such as dispersion properties, flavour, texture, and ease of consumption. Furthermore, the ingredients should be well defined for quality control purposes to ensure standard specifications of the final commodity. For highly nutritious foods these are:
- The materials to be used in the formulation should be locally available and must be part of the normal agricultural production of the country.
- Processing conditions for crops must be well established and a quality control for the industry is necessary to keep the product within the specifications for human consumption.
- If the material to be used in the formulations is not a conventional source of protein for human consumption, chemical, toxicological, and nutritional studies in animals must be carried out in order to assess their safety for human consumption.
- Quality standards must be set up for the new sources of food used in the formulation, as well as for the formulated food itself.
- To assure adequate protein content, formulation of the food should be based on the amino acid content, and then tested in biological assays in animals and then in human subjects, if possible.
- Other nutrients, such as calories, vitamins, and minerals must be added according to the deficiencies in the diet and for the selected population group.
- The formulated food should preferably be designed according to the dietary habits of the population selected, and must also be capable of being consumed in different forms.
- The preparation of the formulated food should be carried out by a private enterprise and must compete in the market as a regular food product.
- It is important to have alternatives in the preparation of the formulated food as far as the raw material is concerned.
- Packaging should be carefully chosen not only to keep the desirable characteristics of the product, but also to present a good image to the consumer.
Contents - Previous - Next