Degradation of phytate in composite wheat/cassava/sorghum bread by activation of intrinsic cereal phytase

The objective of this study was to degrade the phytic acid content in composite wheat/cassava/ sorghum bread by activating intrinsic cereal phytases during the baking process. The aim was to reach a phytate:iron molar ratio <1 to achieve an enhanced iron absorption in humans. Means to activate the phytase included dough preparation at different pH values and temperature as well as pre-soaking of the sorghum flour before baking. The phytic acid and mineral content was measured by high-performance ion chromatography. In the composite bread without pH adjustment of the dough, the phytate content was 1.58 μmol/g. After adjustment of the dough pH to 4.3, the phytate content in the composite bread decreased to 0.86 μmol/g. Soaking of the sorghum flour at 22\ub0C for 3 h at pH 4.3 before baking, further decreased the phytate content to 0.58 μmol/g. Increasing the soaking temperature to 37\ub0C and addition of 10% wheat flour resulted in a phytate content of 0.14 μmol/g in the composite bread, that is a reduction by 97% of the initial phytate content. The phytate:iron molar ratio was then 0.70 and the phytate:zinc molar ratio was 1.1 that is expected to have a positive effect on the absorption of both minerals in humans

Phytate degradation in composite wheat/cassava/sorghum bread: Effects of preincubation of Pichia kudriavzevii TY13 and presence of yeast extract.

Diet based on whole cereal flours is associated with a high prevalence of iron deficiency anemia and zinc deficiency in low/middle-income countries. Such flours contain high content of phytate that chelates minerals such as iron and zinc, making them unavailable for absorption by humans. To improve the mineral absorption, a phytate:iron molar ratio <1 and a phytate:zinc molar ratio <5 is needed to be achieved. This study aimed to improve the phytate degradation in composite wheatcassava-whole sorghum flour bread by adding a phytase releasing yeast Pichia kudriavzevii TY13 in baking, preincubated or not, with addition of yeast extract. The phytate and mineral contents were measured by high-performance ion chromatography. Addition of P. kudriavzevii TY13 to the composite flour dough and fermentation for 2 h at room temperature resulted in a 98% phytate degradation.However, the same phytate reduction in the composite bread was achieved after 1 h fermentation at room temperature with addition of preincubated P. kudriavzevii TY13 plus yeast extract. Increasing the fermentation temperature to 30\ub0C, the phytate content was equally low after fermentation for 1 h with P. kudriavzevii TY13 (preincubated or not) plus yeast extract. In conclusion, a faster reduction of phytate in composite bread was obtained by increasing the fermentation temperature, and addition of P. kudriavzevii TY13 (preincubated or not) with added yeast extract. The phytate to iron molar ratio wasthen 0.2 and the phytate to zinc molar ratio 0.6, which strongly indicates an improved bioavailability of both minerals from such a bread

Study of suitability of cassava and cowpea flours for making bread

This study was done in Tanzania and Mozambique to assess the effect of cassava and cowpea flours singly and in combination in bread making and the degree of acceptability of the bread. Five to 20% cassava and 5 to 30% cowpea were used as wheat flour diluents. As the amount of diluents increased, the loaf volume decreased. The bread size ranged from 560 ml for 30% cowpea bread to 890 ml for 100% wheat bread and from 420 to 620 ml for the pan bread, the highest value being for whole wheat bread and the lowest for 30% cowpea composite bread. The bread weight increased for cowpea composite bread and the combination cassava-cowpea composite breads, ranging from 214 to 250 g for wheat bread and from 260 to 290g for pan bread, the highest values being for 30% cowpea bread and the lowest for 5% cassava composite bread. The specific loaf volumes were 2.39 to 4.07 ml/g for wheat breads and 1.45 to 2.31 ml/g for the pan type breads. Baking losses decreased as the amount of cowpea increased. However, cassava inclusion showed no decrease in baking losses. Cassava composite breads decreased protein content but increased mineral content. Cowpea bread had increased nutrients. The 30% cowpea bread was least accepted as also reflected in the lowest buying preference. For the pan bread, the lowest value was for the combined 10% cassava-5% cowpea bread and the highest value for 10% cowpea bread. This study concluded that up to 15% substitution, the formulation results were promising. Beyond 15% there were changes in organoleptic attributes and poor gas retention reduced loaf volume. Incorporation of cassava or cowpea flour gave a compact structure at higher substitution levels. Increasing levels of cowpea flour in the blends resulted in increased ash and protein and colour changes. The nutrient gains when cowpea is used in composite flour formulation need exploitation.SIDA SARE

Phytate degradation in composite wheat/cassava/sorghum bread: Effects of phytase-secreting yeasts and addition of yeast extracts

Iron deficiency anemia is highly prevalent in developing countries due to the consumption of cereal-based foods rich in phytate that chelates minerals such as iron and zinc making them unavailable for absorption by humans. The aim of the present study was to degrade phytic acid in composite flour (wheat/cassava/sorghum) bread by the addition of phytase-producing yeasts in the baking process to achieve a phytate-to-iron molar rati