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

Abstract

Plasma free amino acids of convalescent malnouished infants and children were determined before the 3 and 4 hours after the first meal of the 27th day of maize endosperm (E) or whole kernel (WK) meal consumption. Three varieties of E—normal, opaque-2 (o₂) or sugary-2 opaque-2 (su₂o₂)—had been consumed in six different sequences during consecutive 9-day periods by six subjects; the same protocol was followed for the corresponding WK meals. Plasma aminogram was expected to reflect the effects of 28 days of maize consumption and 8 days of the last variety consumed, particularly the latter. The significantly poorer absorptions of nitrogen (N) from the E meals were reflected in lower fasting molar ratios of total essentials to total amino acids (TEAA/TAA = 0.192 versus 0.229 for WK). Fasting leucine/TEAA molar ratio was consistently elevated, notably after normal maize. With the exception of one very low (0.067) and one moderately low (0.120) lysine/TEAA ratio, fasting values did not suggest a first-limiting amino acid. Striking postprandial falls singled lysine out as first-limiting in five, possibly six, studies, tryptophan in two studies (normal E and su₂o₂ WK) and probably isoleucine in one o₂ WK study. In two studies (su₂o₂ E and normal WK), lysine and tryptophan seemed equally limiting. The improved lysine and tryptophan contents of o₂ and su₂o₂ maize still leave one or both of these, and possibly isoleucine, as potentially first-limiting for small children.