Luis A. Mejia
Food science and technology play a key role with respect to several issues. For example, it is necessary to maintain the overall quality of the product in terms of the bioavailability of the fortifying agent. Although bioavailability may increase, the product's quality is at risk, especially its stability. Iron, for example, may react with fatty acids in the fortified food, forming free radicals that induce oxidation. Other characteristics that may be affected are colour, taste, odour, and appearance, alterations that should be avoided altogether since they affect consumer acceptability of the product.
This phenomenon, typical in mineral salts, is related to the solubility of the fortifying agent. In general, as solubility of the compound increases, the nutrient is more bioavailable, but at the same time is more reactive with the fortified food, making it less stable and susceptible to the changes described. Table 2 shows, as an example, the addition of several iron salts to different processed foods.
TABLE 2. Relative bioavailability of iron compounds used in food fortification (%)
Iron salts, potentially useful in food fortification, could be divided into different categories. First, the compounds that are soluble in water, such as ferrous sulphate and ferrous gluconate, show the highest bioavailability; however, they can easily alter the quality of most foods (stability, colour, odour) and are used only in infant formulas. Second are compounds that are slightly soluble in water and soluble in diluted acids, for example, ferrous fumarate and ferrous succinate. These compounds have quite good bioavailability in relation to ferrous sulphate, but they still have significant limitations when added to food, except when added to infant cereals, where relative success has been achieved.
Third, compounds that are insoluble in water and slightly soluble in diluted acids, such as iron salts, are more inert and have low reactivity with the food carrier. Therefore, they are likely to be used as fortifying agents. Unfortunately, for the same reasons, they are less bioavailable; for example, ferric salts such as ferric pyrophosphate and ferric orthophosphate are widely used in foods even though their bioavailability is low. However, several compounds of elemental iron that are reduced by different technological processes have higher bioavailability, and at the same time cause no significant changes in food characteristics .
Another important issue is the stability of the fortifying agent. Changes in nutrients' stability may depend on factors such as pH, oxygen, air, light, and temperature (table 3). These should be controlled during processing and storage of fortified foods. A good example is vitamin C, which is extremely unstable under several conditions, especially in high heat and humidity.
TABLE 3. Nutrients, stability under different conditions
Source: Modified from Ref. 5.
Percentage loss of different vitamins during processing and storage may be significant, especially for vitamins C, A, folic acid, and niacin. It is useless to fortify foods if the nutrient concentration decreases after fortification, so that when the food is consumed the nutrient is no longer present.
As part of the fortifying process, a permanent monitoring system of nutrient concentrations is extremely important to ensure the required levels, since high or low concentrations are unacceptable owing to the potential risk of toxicity. Legal issues are important and must be addressed so that country regulations are adhered to, facilitating the implementation of regional fortification.
Food fortification will continue to be an important tool, not only to treat or prevent specific nutritional deficiencies, but also to promote a general state of well-being in different populations, and possibly to prevent certain chronic diseases. The identification and development of fortifying agents that will guarantee product quality and high bioavailability are technological and scientific challenges. Some options for the future are the microencapsulation of nutrients, the use of nutrient bioavailability stimulants (addition of ascorbic or other organic acids to promote iron absorption), and the elimination of inhibitors of mineral absorption in the intestine (e.g., phytates).
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- Bauernfeind JC, Lachance PA, eds. Nutrient additions to food. Nutritional, technological and regulatory aspects. Trumbull, Conn, USA: Food and Nutrition Press, 1991.
- Chopra JG. Enrichment and fortification of foods in Latin America. Am J Public Health 1974;64:19-26.
- Hurrell RA. Prospects for improving the iron fortification of foods. In: Fomon SJ, Slotkin S. eds. Nutritional anemias. New York: Raven Press, 1992.
- Harris RS. General discussion on the stability of nutrients. In: Karmes E, Harris RS, eds. Nutritional evaluation of food processing. 3rd ed. New York: AVl/Van Nostrand Reinhold, 1988.
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