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Nutritional Value of Normal, Opaque-2 and Sugary-2 Opaque-2 Maize Hybrids for Infants and Children

1. Digestibility and Utilization¹

Instituto de Investigacion Nutricional, Apartado 55, Miraflores (Lima), Peru, Department of Agronomy, Purdue University, W. Lafayette, Indiana 47906 and Division of Human Nutrition, Department of International Health, School of Hygiene and Public Health, Gastroenterology and Nutrition Unit, Department of Pediatrics, School of Medicine, The Johns Hopkins University, Baltimore, MD 21205

The opaque-2 (o₂) gene increases the lysine and tryptophan contents of maize and its protein quality; the sugary-2 (su₂) gene improves vitreousness and density but decreases lysine; the double-mutant sugary-2 opaque-2 (su₂o₂) has the improved kernel characteristics and an even higher protein quality than opaque-2. Digestibility of energy and protein, and protein quality of normal, o₂ and su₂o₂, both as endosperm (E) and whole kernel (WK) meals, were studied in eight convalescent malnourished children, 10–25 months of age. Diets provided 100–125 kcal/kg/day, 10% fat, with all of 6.4% protein calories from one of six maize meals or casein. Endosperum meals provided 83.2, 91.2 and 82.1% of energy, WK meals 73.2, 68.6 and 67.2% of energy in respective diets. Apparent N retention from E meals was lower than from WK meals, both lower than from casein. For each type of meal (E and WK) there was strong correlation between lysine "absorbed" and N retention, but this was higher from WK at equal lysine intakes. For 50% of children to match N retention from casein, presumably equal to requirement, they would have to consume 203.9, 148 or 122.5% of energy requirement as normal, o₂ or su₂o₂ E meals, obviously impossible. For WK meals, they would have to consume 108.2, 90.3 or 84.2% of energy as normal, o₂ or su₂o₂.

KEY WORDS: • opaque-2 maize • sugary-2 opaque-2 maize

¹ Supported by Research Contract AID/ta-C-1286 with the Agency for International Development, U.S. Department of State and by Research Grant HD-10111 from the National Institutes of Health, U.S.P.H.S.

² To whom reprint requests should be sent: The Johns Hopkins University, 615 N. Wolfe St., Baltimore, MD 21205.

Manuscript received 5 September 1979.