Optimization of the Protein Nutritive Value of Wheat/Cassava Breadmix by Supplementing with Limiting Amino-Acids (L-Lysine & L-Methionine)

Abstract

This study was carried out in line with the National policy on bread to incorporate 10% cassava flour into wheat flour for all bread baked in Nigeria. The objective of this study was to investigate if the addition of 10% cassava flour or more could be accommodated without compromising the nutritive value of bread. The effect of fortifying with limiting amino-acids was also investigated. This study employed a feeding trial and bioassay of tissues from albino rats of Wistar strain, to evaluate the effect of supplementing various levels of wheat/cassava bread mix feed, with 0.1% L-lysine and 0.1% L-methionine. Nine different diet regimens were used with four rats in each diet group. Cassava (100%) diet group was used as the control; and the diets fortified with 0.1% L-lysine and 0.1% Lmethionine used as secondary control. The parameters measured as 'markers' of nutritive value included: body weight changes, food conversion ratio (FCR) and net protein utilisation (NPU). The effects of dietary intake of the various wheat/cassava supplemented diets on haematological indices such as mean corpuscular haemoglobin concentration and biochemical indices such as cortisol, total protein and albumin in the plasma of fed rats were also determined. Results indicated that both 10% and 20% cassava input supported adequate nutritional and biochemical development of the fed rats, although fortification of the diets with 0.1% L-lysine and 0.1% L-methionine resulted in 10 – 20% improvement in all the nutritional indicators measured. Based on the results of this study, it was concluded that incorporation of 20% cassava flour into wheat bread supplemented with L-lysine and L-methionine is nutritionally better than, but haematologically and biochemically comparable to whole wheat bread in rats. Therefore, this findings lend support to the national policy on nutrient fortification and cassava incorporation into wheatbread for the general goal of improving food security in Nigeria.

Keywords: Bread fortification, Weanling rat, L-methionine, L-Lysine, haematological indices, biochemical indices

Nigerian Journal of Parasitology, Vol. 32 [2] September 2011, pp. 287-295