Production and characterization of Protein isolates from locally produced mustard meal for the development of biscuit

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Addis Ababa University


A process for the preparation of Holetta 1 mustard protein isolate, comprising steps such as ground the seed, removal of oil with hexane, followed by extraction at alkaline pH 10, 11 and 12. The protein was subjected to separation by centrifugation, neutralization, washing and freeze-drying. The parameters evaluated were protein yield, purity and presence of some antinutritional factors. The protein yield was 56-80%.The purity of the protein isolate was 73.29%, 75.40% and 68.225 at pH value of 10, 11 and 12 respectively. The antinutritional factors levels of defatted meal was as follows, glucosinolates represents 5.1%, phytate was 3.19% and tannins was 0.35% but after processing its value was 0.013%, 0.035 and 0.65% at pH10, 0.012%, 0.03% and 0.75% at pH11 and 0.02%, 0.215% and 1.45% at pH12 respectively. The lowest protein solubility was achieved at pH 5.some functional properties such as water adsorption(WA), fat adsorption (FA), emulsifying activiy (EA) and foaming capacity (FC) were evaluated.Holetta1 mustard defatted meal were compared with soybean meal in terms of functional properties. The tested result showed a high water absorbtion and was superior to soybean meal in FA, EA and foaming properties The chemical composition results of mustard variety of Holleta 1 defatted meal was 38.42% of protein, 5.03% of ash, 7.10% of moisture, 31.15% of fiber, 7.79% of crude fat and 10.53% of carbohydrate but after processing, the mustard precipitated protein isolate contained 75.40% of protein, 2.64% of ash, 7.97% of moisture, 0.08% of fiber, 12.61% of crude fat and 1.31% of carbohydrate. In addition to the above, this study evaluated the effectiveness of substituting different concentrations of mustard protein isolated (MPI) on the physicochemical and sensory properties of biscuits. Proximate chemical analysis results of biscuits showed that fortification increased protein contents from 9.67% to 12.77% as well as increased moisture and fat content from 4.18% and 8.26% to 9.46% and 8.49% respectively but carbohydrate content was decrease from 76.79% to 68.16%. Fortification processes were conducted by substituting specified concentrations (3%, 6%, and 9%) MPI from the total percent of wheat flour (100%). Results indicated that fortification decreased spread factor compared with the control (100% wheat flour). Sensory results showed that as the fortified MPI ratios increased xiii most of liking attributes decreased. Sensory analysis also showed that 3% of fortified MPI provided the best quality ratios within each type of fortification. Fortification of MPI could be used in production of high-protein biscuits. The result obtained for fortification of biscuit with mustard protein isolate, the incorporation of MPI ratio increase with the decrease of hardness (strength) from 20.2N, 20N, 17.2N and 15.7N for control (100% wheat flour), 3% MPI, 6%MPI and 9% MPI fortified biscuit respectively. Regarding to profitability, gross earning will be 46,200,000birr, ROI = 26.84%, pay back period = 3.2 year and break even point = 17.54%



Centrifugation, Neutralization