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Appendix A QPM's Future in the United States This report highlights the potential of quality-protein maize (QPM) for developing nations. However, maize (corn) is the largest crop in the United States, which each year produces more than 100 million tonsâalmost half the world's total. It seems probable, therefore, that any report on a nutritionally improved corn will stimulate considerable local interest. Accordingly, we include this brief appendix to outline some aspects of the crop's domestic promise.1 * * * Although the discovery of opaque-2 corn's exceptional nutritive qualities was made at Purdue University in 1963, so far it has been put to little use in the United States. Moreover, the new, hard- endosperm forms that are known as QPM have not been used here at all. Despite this lack of local recognition, however, QPM could become a noteworthy part of the North American corn industry. Any improve- ment in the fundamental nutritional value of corn is likely to create new, unique, and premium markets. There is, for instance, distinct promise for breakfast cereals and snack foods, both of which are constantly criticized for their low nutritional value. For them, QPM might provide both a nutritious product and an important public relations breakthrough. QPM, however, is not ready for immediate use in the United States. It was created in Mexico with the needs of malnourished people in Africa, Asia, and Latin America in mind. As a result, it is available at present only in open-pollinated types, not the hybrids mainly used in North America. Research is needed to tailor QPM to U.S. environments and farming needs. A research group at Texas A & M University has begun such research with promising early results. In Florida and Texas, their various QPMs have grown well. In 1987, inbred lines with acceptable 1 In this appendix, we use the units most meaningful to American readers involved in farming and agribusiness. For the same reason, we use the name "corn" instead of "maize." 77
78 QUALITY-PROTEIN MAIZE agronomic properties were crossed to produce experimental QPM hybrids.2 QPMs suited to Corn Belt conditions are under development at Purdue University. Four temperate populations (NTR1, NTR2, ITR, and STR) have proved to be well adapted. Also at Purdue, a number of Corn Belt inbred opaque-2 lines are being converted to QPM types. These plants are suited to Corn Belt conditions and retain their nutritive qualities, but they are not yet in forms suitable for release to farmers.3 DRY-MILLING Although QPM's progenitor, the soft-endosperm opaque-2 corn, has been known for 25 years, its poor milling qualities meant that it was inappropriate for dry-milling. (The soft endosperm breaks so easily that it produces poor yields of grits.) QPM, on the other hand, is of a hard-endosperm type and gives a good yield of grits. Thus, it seems promising for items such as snack foods and breakfast cereals.4 The Texas A & M research group has shown already that QPM can easily be processed into tortilla chips and other products without greatly modifying the normal process. Acceptable tortillas and tortilla chips with a 50-percent improvement in nutritional value resulted from QPM.5'6 The researchers report the following results: ⢠QPM had smaller, more dense, harder kernels than food-grade corn. ⢠QPM contained twice as much lysine, tryptophan, and albumins/ globulins as food-grade corn. ⢠Rats fed QPM gained at least twice as much weight as those fed food-grade corn and consequently had improved feed:gain ratios. ⢠Tortillas and tortilla chips of both QPM and common corn had significantly higher dry matter and energy digestibilities but lower apparent protein digestibilities than their respective raw grains. WET-MILLING In wet-milling, the corn kernels are soaked before being processed to separate the starch, which is converted into dextrose, sweeteners, and myriad other products. The soak water is evaporated to recover 2 Information from L.W. Rooney and A.J. Bockholt. 3 Information from D.V. Glover. 4 The processing might have to be slightly modified because QPM tends to have a larger germ than normal and may give an oily dry-milled products. 5 Sproule, 1985. 6 Sproule, et al., 1988.
APPENDIX A 79 "gluten meal." Although a by-product, gluten meal contributes im- portantly to the profitability of the process. If QPM were substituted for common corn, the gluten meal's nutritional quality, and therefore its selling price, would likely rise substantially. The early opaque-2 corns were unsuitable for wet-milling because of their lower than normal starch yieldsâ15 percent lower in some cases. However, the new QPMs essentially can equal the 71 percent starch yield of normal corn.7 Thus, for them, the extra value of the gluten meal by-product may be economically significant. ANIMAL FEED Another area where QPM may have considerable domestic impact is the livestock industry. One U.S. company8 offers for sale nutritionally improved corn hybrids based on soft-endosperm opaque-2 corn.9 Reportedly, these hybrids can produce 97 percent of the yield of normal corn hybrids. Feeding trials employing them have shown good results and have stimulated their wider use in several parts of the country, primarily in feed for hogs. These commercial hybrids of opaque-2 soft-endosperm corn have attained a small but avid following. Official figures are unavailable because farmers who raise these varieties feed them exclusively to their own livestock and never sell them to elevators. However, unofficial estimates place production at well over a million tons a year. Testimonials from farmers who feed opaque-2 corn silage along with opaque-2 corn grain to dairy herds claim that it increases the milk production. Such claims remain unverified by controlled experiments, although careful studies at the Nebraska Experiment Station have given some preliminary supporting evidence of the value of nutritionally improved corn as livestock feed.10 These experiments show that when opaque- 2, soft-endosperm corn is fed in place of normal corn to all classes of pigs, from weaning to finishing, the farmer can reduce the total level of dietary protein supplement (soybean meal) by 2 percent. This is significant because soybean meal currently sells at about three times the price of corn. In the University of Nebraska study, some of the newer opaque-2 corn varieties produced yields comparable to those of normal corn hybrids. When diets were formulated on an equal lysine basis, pig performance was similar for normal and opaque-2 corn, even though the normal-corn diets contained about 3 percent more soybean meal than the opaque-2 corn diets. 7 Information from D.V. Glover. 8 Crow's Hybrid Corn Company (see Research Contacts). 9 Commonly marketed under the name high-lysine corn. 1"Ascheetal., 1985.
