Improvement of the protein quality of corn with soybean protein

In most Central American countries, lime-treated corn provides 31% of the total protein and 45% of the energy intake, and beans 24% of the protein and 12% of the calories. Such diet is low in protein quality and quantity, as well as in energy. To overcome these deficiencies, corn can be supplemented either with its limiting amino acids, lysine and tryptophan, or better still, with whole soybeans which improve not only the amount and quality of the protein consumed but, because of their high oil content, the energy intake as well. In addition, animal experiments have shown that for maximum utilization of these nutrients, adequate vitamin and mineral intake is indispensable. At a level of 15 parts of whole soybean or 8 parts soybean-derived products, to 85--92 parts of corn there were no significant changes in the rheological or organoleptic characteristics of the tortilla prepared there of. Higher levels of soybean products, however, may affect the consistency of the lime-treated corn dough and, therefore, the tortilla acceptability. Since corn is usually cooked, but not ground, at home, the soybean supplement can be successfully added at the wet--milling stage of dough preparation or whole soybeans and corn may be cooked together, when a nutritional intervention is desired at the village level. At an industrial scale, if whole soybeans are used, they may be cooked together with corn, and if soy flour is used, this can be mixed at the end of the process when the cooked corn is ground to a flour. A flow diagram for supplementing corn with 15% whole soybeans is presented. If interventions of this nature are to be successful, there is need for increasing the prestige of corn-based food, as well as of nutrition education programs in these populations.