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Session 4-A: Achieving better nutrition

Chairman R. Devadas
Rapporteur Y.G. Deosthale

Fortification of foods

M.R. Chandrasekhara

Abstract
Introduction
Enrichment of staple foods
Fortification of foods
Large-scale consumer trials
Indian experience
Is food fortification necessary?
Conclusion
References

Abstract

Processing of foods involves loss of nutrients. Jo make good such losses, foods are enriched with nutrients. Other staple foods are fortified by governments and other bodies, with the object of overcoming endemic nutritional diseases or as a prophylactic measure. Manufactured consumer goods are also fortified with nutrients, either with the object of ensuring the nutritional adequacy of the product or to achieve better sales. In India several such schemes have been tried with more or less success. Fortification, when undertaken, has to be based on a detailed study of the need and the mode of fortification. Economics, consumer acceptability, and means of achieving the objective should be the guidelines for such a project.

This paper discusses the implications of fortification with minerals, vitamins, amino acids, and proteins. Examples of such fortifications like those of the early experiments of the Central Food Technological Research Institute, Mysore, such as the preparation of synthetic rice using groundnut proteins as a fortificant for protein-poor tapioca flour, preparation of multi-purpose food as a protein concentrate to be used by the consumer as a fortificant of food to provide both vitamins and proteins, and other experiments carried out in Tunisia, Thailand, and Guatemala where wheat flour, rice and corn flour were fortified with vitamins, amino acids and soy flour (in the case of Guatemala) are discussed in detail. The need for fortification and the sociological overtones of fortification are discussed in detail. A striking example of an unproductive type of fortification is shown in the case of baby foods. In the course of a day, a child fed with baby foods and perhaps some weaning foods, receives as much as 109 to 295 per cent of its vitamin requirements. To overcome this, a method has been suggested where vitamin fortification is related to the calorie requirements (or caloric consumption) of the child.

Introduction

All agricultural raw materials are processed before they can be used as foods. Cereals and pulses are debunked and debranned or polished. Milk is pasteurized or boiled, homogenized, concentrated, or dried. Fruits, if they are to be processed, are expressed, pasteurized, or concentrated. Meat and meat products, if made into processed products, are heat-processed. In all these processing stages, some portion of the nutrients is destroyed or otherwise lost. Some nutrient loss is inevitable, for the raw foods cannot be consumed or preserved.

The term enrichment has been used to signify the act of adding the nutrients that are lost in processing back to the processed food, in such a way that the nutritional value corresponds to that of the unprocessed material.

On the other hand, to overcome certain endemic nutritional diseases or to increase the nutritional quality of staple foods, governments may undertake programmes of providing nutritional ingredients by using staple foods as the medium. Such a process is generally termed fortification (Borenstein 1974). Fortification is also the term used when nutrients are added to new types of foods to make them resemble their natural counterparts. For example, the image to emulate when making synthetic soft drinks is lemon or orange juice, for vegetable milks it is cow milk, and for textured vegetable proteins it is meat or meat products. The terms "enrichment," "fortification," or "nutrification" are often used interchangeably.

Enrichment of staple foods

In order to overcome the losses of vitamins and minerals during milling of wheat, enrichment with these has been practised for the past several decades. In the United States, the Food and Drug Act of 1943 prescribed enrichment of wheat flour with thiamine, riboflavin, niacin, and iron. In the United Kingdom in 1942, food scarcity brought about by the German submarine blockade made the Government enforce the long-extraction order for wheat milling and, to overcome the effect of phytates in bran, enrichment of flour with calcium carbonate (0.15 per cent). This was further increased to 0.3 per cent in 1946 (Sur and Lyengar 1953).

Mandatory enrichment of certain staple foods has now been prescribed in some countries (table 1). In a few other countries recommendations are made for such enrichment. The United States has prescribed enrichment of flour (wheat), self-raising flour, bread, rolls, and buns, and milk and milk products ("Standards of Identity" 1974). The nutrients used for enrichment are the vitamins of the B-group (thiamine, riboflavin, and niacin) and the minerals, calcium and iron.

TABLE 1. Enrichment of Cereal Products

1. Average of the minimum and maximum limits
2. Legally enforced.
   Source: Encyclopedia of Food Science, Peterson Johnsons, vol. 3, AVI Publication, Westport, Conn, 1978.

Mandatory enrichment of staple foods is practised only to a limited extent in India. Vanaspati (hydrogenated oil) has to be enriched with vitamin A (25 IU/g). This has evoked a controversy in recent times, since it has been shown that vitamin A is subject to serious losses, particularly when it is used as a frying medium. Besides, the vitamin A in vanaspati is not of benefit to the population that needs it most, as they may not be able to buy vanaspati (Achaya personal communication 1981).

Mandatory enrichment is also prescribed for margarine (30 IU vitamin A/g) and iodized salt (20 ppm potassium iodide).

Of the vitamins used to enrich wheat flour, it has been reported that 35 per cent of thiamine and 18 to 27 per cent of riboflavin are lost during the processes of cooking or frying used in making doughnuts (Borenstein 1974). Brooke (1968) has reported losses of 50 per cent of added vitamin B1, 39 per cent of vitamin B2, and 40 per cent of niacin.

Fortification of foods

To overcome a nutritional disease prevalent in a large section of the population, the government or another agency may undertake the supply of the deficient nutritional factor(s) through the medium of food. To do this the missing nutrient will have to be put into a food that the target population is consuming. Many governments have launched such programmes of fortification. Some of the projects have been successful, others have been abandoned mid way.

To be successful, a programme of this nature has to be based on very sound planning. First it has to be ascertained that a need for fortification exists. Nutritional and health surveys to establish the widespread occurrence of a deficiency disease have to precede any such decision. The nutritional diseases that can be prevented by measures of intervention are caused by vitamin and mineral deficiencies. Foods can also be fortified with amino acids or protein concentrates in order to bring about better utilization of the protein. In many nutrition intervention programmes all three components have been combined.

Austin (1979) has considered in detail the factors that govern the implementation of a nutritional intervention programme. They are (a) nutritional need, which implies a detailed health and nutrition survey; (b) commodity system structure, which decides on the food vehicle to be fortified, depending on the food habits, the commodity marketing, and buying habits of the population; (c) technology for fortification; (d) consumer acceptability, which probably is the crux of the success of the project ; and, finally, (e) the economics.

Any programme of fortification will be viable only if all these factors are very carefully surveyed and analysed.

Techniques of Fortification

Techniques of fortification depend on the nature of the medium that is to be fortified, which, in turn, is decided upon after a detailed food habit survey. If it is decided to fortify a staple grain like wheat, a predetermined quantity of the pre-mix containing the nutrients is metered into the mainstream of the flour, and thoroughly mixed.

A similar technique is followed when fortifying milk. The fortificant is added into the mainstream of milk or concentrated milk. Fortification can be done to the dried milk powder also by mixing the fortificant with it.

In all cases, a pre-mix of the fortificant is prepared earlier, so that it provides sufficient fortification when added in the ratio of 0.1 to 0.5 per cent to the bulk.

Fortification of Rice Grains

Rice is eaten as cooked grain so fortification by mixing in fortificants is not possible. Three techniques have been adopted for such grains.

Soaking and drying. A portion of the grains (perhaps 1 per cent of less of the bulk) is soaked in a concentrated solution of vitamins and minerals. The grains are dried and distributed within the bulk in the required proportion. This has two disadvantages. If the target population has not been educated about the fortification programme, it can easily pick out the grains, as they are yellow (due to riboflavin) and discard them. Or, again, rice is usually washed before cooking and in this process the fortificants can wash out.

Spraying. Spraying is similar to the above process but the fortificant is repeatedly sprayed on to the premix, dried and again sprayed till the required concentration is achieved. The final spray usually takes the form of a water-resistant coat to prevent any leaching out of the fortificants (Young 1979).

In this case also the target group might remove the fortified grains. In addition, after cooking, the fortified grain will colour parts of the rest of the rice giving rise to unpleasant yellow patches.

Synthetic grain. The fortificant can be mixed with rice flour and other flours, extruded through a macaroni press with suitable dies. and dried.

The advantage of this process is that it is much simpler than the two earlier processes and can accommodate even a blend of amino acids. However, the grains are again distinctly separate from the other grains and are easily distinguishable from the bulk.

Fortification with Amino Acids and Protein Concentrates

The programmes of fortification of food with vitamins and minerals always stem from a realization that provision of vitamins or minerals can overcome clearly defined deficiencies. Fortification of cereal flours with amino acids or protein concentrates, however, is not based on such definite evidence.

The chemical score of some cereals is shown in table 2, which shows that in all of them the limiting amino acid compared to egg protein is lysine, threonine, and tryptophan in that order.

TABLE 2. Chemical Score of Cereals^a

a. Only three amino acids are considered here.
Source: ICMR 1971

Supplementation of cereal diets with lysine or lysine and threonine have always increased the protein efficiency ratio (PER) indicating a better utilization of the rice protein (Jansen 1974). Studies with children have not always given such unequivocal results, though several research workers have reported beneficial effects (Jansen 1974; Pereira et al. 1969). In many of these experiments, the fortified cereal flour has formed only a part of the diet consumed by the children. However, there have also been reports that have not confirmed the supplemental effect with children (Reddy 1971; Albernathy et al. 1972). A detailed discussion of this has been presented in a Protein Advisory Group (PAG) document (1969).

The advantage of fortification of cereals with amino acids is that there is the least amount of change in the nature of the product. The food is not altered in colour or taste. Both L-lysine and L-threonine do not leave any residual taste or flavour. But addition of dL-methionine brings about a sulphurous taste and flavour when the fortified flours are cooked or heated. This can be avoided by using the hydroxy analogue of methionine, which has the same biological effect as dL-methionine (Protein Advisory Group 1960). With lysine and threonine, toxic effects have not been reported but toxic effects with excess methionine have been reported (Harper et al. 1970; Jansen 1974).

Fortification of cereals with protein concentrates (edible oilseed cakes) has also been advocated. At levels of 8 per cent, Parthasarathy et al. (1964) have shown supplemental effects when de-oiled peanut meal and de-oiled soy meal were added to diets based on ragi (Eleucine coracana) and whole wheat. Such fortification brings about problems of colour, taste, and consumer acceptability. The protein content of the total mix is raised by about 3 to 4 per cent but the content of the limiting amino acid, lysine, is hardly raised with added edible peanut meal.

Large-scale consumer trials

The US Agency for International Development (USAID) instituted three major field trials for testing out cereal fortification during the period 1970-76. The selected places were Tunisia, where wheat flour used for making bread was fortified; Thailand, where rice grains were fortified; and Guatemala, where corn used for making tortillas was fortified. The nature and levels of fortification are shown in table 3. The investigations were characterized by detailed preliminary nutritional and commodity surveys, technology and feasibility of fortification, and overall effects of fortification. In each place, central fortification as opposed to retail fortification (where the individual consumer is given the option to add the fortificant to the flour when he comes to the mill with the grain for powdering) was also tested. The report of these three investigations provides a detailed study of cereal fortification (Austin 1979). Consumer acceptance of the fortified food in all three places was fairly good. In Thailand there were some difficulties because of the fortificant grain being different from the bulk of rice in colour and taste. But generally it was accepted when the reasons were explained.

TABLE 3. Fortification of Staple Foods - USAID Projects

Source: Austin 1979.

The conclusions drawn from these three field trials were: "The Guatemala study produced very slight but inconclusive evidence of decrease in morbidity or mortality rates, but in Tunisia and Thailand no detectable beneficial effects were observed" (Austin 1979).

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