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Quality Protein Maize
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Quality Protein Maize
Quality Protein Maize (QPM) is a family of maize varieties. QPM grain contains nearly twice as much lysine and tryptophan, amino acids that are essential for humans and monogastric animals but are limiting amino acids in grains. QPM is a product of conventional plant breeding (i.e., it is not genetically modified) and an example of biofortification.
QPM was developed by Surinder Vasal and Evangelina Villegas at the International Maize and Wheat Improvement Center (CIMMYT) in the late 1990s. For their achievement, they won the 2000 World Food Prize.
In Central and South America, Africa, and Asia, several hundred million people rely on maize as their principal daily food, for weaning babies, and for feeding livestock. Unfortunately maize (corn) has two significant flaws; it lacks the full range of amino acids, namely lysine and tryptophan, needed to produce proteins, and has its niacin (vitamin B3) bound in an indigestible complex. The Mayans and Aztecs used to boil maize in alkaline limewater, nixtamalization, which broke down the complex so that the niacin became available. However, in the main, this practice did not transfer to the Old World or settlers in the "New World" which resulted in epidemics of pellagra from the 16th century onwards. In addition, diets high in corn produce a condition known as wet-malnutrition – a person is receiving sufficient calories, but her or his body malfunctions due to a lack of protein. A chronic lack of protein in the diet leads to kwashiorkor.
Thus, conventional maize is a poor-quality food staple; unless consumed as part of a varied diet – which is beyond the means of most people in the developing world.
QPM produces 70–100% more of lysine and tryptophan than the most modern varieties of tropical maize. These two amino acids allow the body to manufacture complete proteins, thereby eliminating wet-malnutrition. In addition tryptophan can be converted in the body to niacin, which theoretically reduces the incidence of pellagra.
Modified maize with higher protein content dated back to the 1920s, and the "opaque-2" variety had been developed in 1963. While its lysine and tryptophan levels were better than those of conventional maize, opaque-2 had lower yields and a soft, chalky kernel, which made it more susceptible to ear rot and insect damage. Moreover, the taste and kernel appearance dissatisfied consumers, who ultimately rejected the enhanced-protein varieties in the market.
Surinder Vasal and Evangelina Villegas began their collaborative research in Mexico in the early 1970s while they were working at CIMMYT. Dr. Villegas was in charge of the lab investigating protein quality and Dr. Vasal was a plant breeder newly assigned to work on developing QPM varieties that would gain widespread acceptance.
Integrating cereal chemistry and plant breeding techniques, Drs. Vasal and Villegas collaborated to combine the existing opaque-2 maize with genetic modifiers. Through the 1970s, they produced and analyzed germplasms at an astonishing rate, sometimes processing up to 25,000 samples a year. By the mid-1980s, they had produced a QPM germplasm with hard kernel characteristics and good taste similar to the traditional grain and with much higher quality levels of lysine and tryptophan.
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Quality Protein Maize
Quality Protein Maize (QPM) is a family of maize varieties. QPM grain contains nearly twice as much lysine and tryptophan, amino acids that are essential for humans and monogastric animals but are limiting amino acids in grains. QPM is a product of conventional plant breeding (i.e., it is not genetically modified) and an example of biofortification.
QPM was developed by Surinder Vasal and Evangelina Villegas at the International Maize and Wheat Improvement Center (CIMMYT) in the late 1990s. For their achievement, they won the 2000 World Food Prize.
In Central and South America, Africa, and Asia, several hundred million people rely on maize as their principal daily food, for weaning babies, and for feeding livestock. Unfortunately maize (corn) has two significant flaws; it lacks the full range of amino acids, namely lysine and tryptophan, needed to produce proteins, and has its niacin (vitamin B3) bound in an indigestible complex. The Mayans and Aztecs used to boil maize in alkaline limewater, nixtamalization, which broke down the complex so that the niacin became available. However, in the main, this practice did not transfer to the Old World or settlers in the "New World" which resulted in epidemics of pellagra from the 16th century onwards. In addition, diets high in corn produce a condition known as wet-malnutrition – a person is receiving sufficient calories, but her or his body malfunctions due to a lack of protein. A chronic lack of protein in the diet leads to kwashiorkor.
Thus, conventional maize is a poor-quality food staple; unless consumed as part of a varied diet – which is beyond the means of most people in the developing world.
QPM produces 70–100% more of lysine and tryptophan than the most modern varieties of tropical maize. These two amino acids allow the body to manufacture complete proteins, thereby eliminating wet-malnutrition. In addition tryptophan can be converted in the body to niacin, which theoretically reduces the incidence of pellagra.
Modified maize with higher protein content dated back to the 1920s, and the "opaque-2" variety had been developed in 1963. While its lysine and tryptophan levels were better than those of conventional maize, opaque-2 had lower yields and a soft, chalky kernel, which made it more susceptible to ear rot and insect damage. Moreover, the taste and kernel appearance dissatisfied consumers, who ultimately rejected the enhanced-protein varieties in the market.
Surinder Vasal and Evangelina Villegas began their collaborative research in Mexico in the early 1970s while they were working at CIMMYT. Dr. Villegas was in charge of the lab investigating protein quality and Dr. Vasal was a plant breeder newly assigned to work on developing QPM varieties that would gain widespread acceptance.
Integrating cereal chemistry and plant breeding techniques, Drs. Vasal and Villegas collaborated to combine the existing opaque-2 maize with genetic modifiers. Through the 1970s, they produced and analyzed germplasms at an astonishing rate, sometimes processing up to 25,000 samples a year. By the mid-1980s, they had produced a QPM germplasm with hard kernel characteristics and good taste similar to the traditional grain and with much higher quality levels of lysine and tryptophan.