Soy enhances the protein quality of wheat bread because of its lysine content which is deficient in wheat. The aim of this work was to use high levels of soy flour in wheat bread in order to maximise the potential of soy flour protein in an attempt to address Protein Energy Malnutrition in developing counties. Raw soy flour (RSF) and physically modified soy flours (PMSF1 and PMSF2) were used for the preparation of the composite dough with wheat flour. The two physically modified soy flours were prepared by steam flushing (PMSF2) and water boiling (PMSF1) of raw soy beans before flour preparation. Physical modification of soy flour was chosen over chemical modification because of its practical significance in developing countries. The Farinograph and Extensograph were used to study the effect of Lascorbic acid and physical modification of soy flour on the rheological properties of soy-wheat composite doughs at various ratios up to 50% soy flour. Soy-wheat composite doughs made from physically modified soy flour (PMSF) exhibited higher resistance to extension (Rm), greater tolerance to mixing, better mixing stability, higher water uptake rate and water absorption than the soy-wheat composite doughs made from raw soy flour (RSF).The physical modification process provides a relatively simple method for improving the baking quality of soy flour, in combination with wheat flour, for use at the village level in regions where soy can be grown and where wheat grain is imported. Using physically modified soy flour (PMSF2) to prepare soy-wheat dough, a mathematical model was developed from estimated regression coefficients of L-ascorbic acid and water percentages (30% w/w soy flour) on soy-wheat dough DSC water evaporation enthalpies. The model was successfully used for the prediction of loaf volumes and for the formulation of soy-wheat breads. A daily serving of 100 to 200 grams of this bread was calculated to provide 60 -100% of the lysine and protein requirements (FAO/WHO) of children and adults. The resultant breads developed in this project thus offer an attractive and sustainable food that is nutritionally superior. / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:ADTP/235283 |
| Date | January 2006 |
| Creators | Maforimbo, Elizabeth, University of Western Sydney, College of Health and Science, School of Natural Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
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