Comparative nutrition of normal maize (Zea mays L.) quality protein maize and wheat (Triticum spp.) flour and blends for 'pan de sal' making

Proximate composition, total lysine, total tryptophan, carbohydrates and mineral content of quality protein maize (QPM) flours (SYQ6 and IPB Var 6), were determined and compared to normal maize flours (IPB Var 13 and IPB Var 8) and wheat flour. The effects of cultivar, baking and flour blends on the nutritional parameters were determined. Comparable levels of percent crude protein were observed for all flours and blends. However, total lysine of QPM flours were found to be about 16% and 27% higher than normal maize flours and wheat flour, respectively. Consequently, significantly higher lysine amino acid score of both QPM flours (82.23-87.38) compared to normal maize and wheat flours (46.37-66.72%) were also determined. Comparison of total lysine and lysine amino acid scores of QPM flour blends to normal maize flour blends and pure wheat flour also showed similar trends. Total tryptophan, of both QPM flours were found to have comparable levels compared to wheat flour but were about 19% higher than normal maize flour. Similar trends were observed for tryptophan amino acid score. All unbaked flour blends showed comparable levels of total tryptophan (0.98-1.23 mg/g) and tryptopan score (54.90-65.98%). However, upon baking QPM white (IPB Var 6) flour blends had comparable tryptophan levels compared to control (1.56-1.82 mg/g) and higher levels compared to normal maize flour blends (1.43-1.63 mg/g). Carbohydrates content of the corn flours and blends (65.58-88.22%) were significantly higher than the carbohydrates content of wheat flour (63.54%). The amylose:amylopectin ratio were determined to evaluate the glycemic index (GI). Higher amylose:amylopectin ratio indicates a low GI. Normal maize flours and wheat flour had the significantly highest amylose:amylopectin ratio while QPM flours had the lowest ratio. Mineral analysis showed that IPB Var 8 (normal white) maize flour had the highest Na, K, Ca, Mg, Zn, Fe and P content. IPB Var 6 (QPM white), on the other hand, contained the lowest amount of all the minerals analyzed. Cu content of all the flours were comparable. Maize flours contained higher amount of minerals than wheat flour except for Ca and Fe. Similar trends were observed in the maize-wheat flour blends. Sensory evaluation results showed that composite breads from 90:10 up to 70:30 (wheat:maize flour) blends have comparable overall acceptability compared to pure wheat bread.