Availability of essential amino acids in corn flour and corn bread.

The availability of nitrogen, lysine and 9 essential amino acids was determined in corn before and after baking. Lysine availability was determined by the growth response method on weaning rats using regression analysis of body weight gain or moisture gain against lysine consumed from corn flour and corn bread. The results show a high correlation between lysine consumed and weight gain or moisture gain (r = 0.95) for rats fed the standard diets for 3 weeks. A good correlation was also obtained for corn bread. The results of lysine availability show that baking greatly improves availability by both ways of calculation. The availability of nitrogen and essential amino acids were also investigated by the balance trials with rats. Results show that availability values for nitrogen and all amino acids except threonine increased by baking. Data for food intake, weight gain, food efficiency, PER, NPR and true digestibility revealed that baking had little or no effect on nutritive value of corn tested in this investigation.

The effect of baking on availability of essential amino acids in wheat.

Lysine availability in wheat flour and bread was determined by the growth response method on rats using regression analysis relating gain in body weight and/or in body water to lysine consumed at two extractions, 87% and 72%. The availability of nitrogen and of essential amino acids were also determined by the balance trials method (fecal analysis method) with rats. The results of growth method show that baking increases lysine availability on the basis of body water gain. Also extraction levels affect lysine availability on the basis of change in body water. Wheat flour and bread of 72% extraction has more lysine availability values than the 87% extraction on the basis of moisture gain. Results of balance trials show that neither the extraction level nor the baking has a significant effect on essential amino acids availability. A fairly good correlation is obtained for wheat flour and bread for the two extractions. Values of change in weight, food efficiency, PER, NPR and true digestibility showed that baking and level of extraction of wheat has no significant effect on the nutritive value of wheat investigated in the present study.