A process for the preparation of Holetta 1 mustard protein isolate, comprising steps such asrnground the seed, removal of oil with hexane, followed by extraction at alkaline pH 10, 11 andrn12. The protein was subjected to separation by centrifugation, neutralization, washing andrnfreeze-drying. The parameters evaluated were protein yield, purity and presence of somernantinutritional factors. The protein yield was 56-80%.The purity of the protein isolate wasrn73.29%, 75.40% and 68.225 at pH value of 10, 11 and 12 respectively. The antinutritionalrnfactors levels of defatted meal was as follows, glucosinolates represents 5.1%, phytate wasrn3.19% and tannins was 0.35% but after processing its value was 0.013%, 0.035 and 0.65% atrnpH10, 0.012%, 0.03% and 0.75% at pH11 and 0.02%, 0.215% and 1.45% at pH12rnrespectively. The lowest protein solubility was achieved at pH 5.some functional propertiesrnsuch as water adsorption(WA), fat adsorption (FA), emulsifying activiy (EA) and foamingrncapacity (FC) were evaluated.Holetta1 mustard defatted meal were compared with soybeanrnmeal in terms of functional properties. The tested result showed a high water absorbtion andrnwas superior to soybean meal in FA, EA and foaming propertiesrnThe chemical composition results of mustard variety of Holleta 1 defatted meal was 38.42%rnof protein, 5.03% of ash, 7.10% of moisture, 31.15% of fiber, 7.79% of crude fat and 10.53%rnof carbohydrate but after processing, the mustard precipitated protein isolate containedrn75.40% of protein, 2.64% of ash, 7.97% of moisture, 0.08% of fiber, 12.61% of crude fat andrn1.31% of carbohydrate.rnIn addition to the above, this study evaluated the effectiveness of substituting differentrnconcentrations of mustard protein isolated (MPI) on the physicochemical and sensoryrnproperties of biscuits. Proximate chemical analysis results of biscuits showed thatrnfortification increased protein contents from 9.67% to 12.77% as well as increased moisturernand fat content from 4.18% and 8.26% to 9.46% and 8.49% respectively but carbohydraterncontent was decrease from 76.79% to 68.16%. Fortification processes were conducted byrnsubstituting specified concentrations (3%, 6%, and 9%) MPI from the total percent of wheatrnflour (100%). Results indicated that fortification decreased spread factor compared with therncontrol (100% wheat flour). Sensory results showed that as the fortified MPI ratios increasedrnxiiirnmost of liking attributes decreased. Sensory analysis also showed that 3% of fortified MPIrnprovided the best quality ratios within each type of fortification. Fortification of MPI couldrnbe used in production of high-protein biscuits.rnThe result obtained for fortification of biscuit with mustard protein isolate, the incorporationrnof MPI ratio increase with the decrease of hardness (strength) from 20.2N, 20N, 17.2N andrn15.7N for control (100% wheat flour), 3% MPI, 6%MPI and 9% MPI fortified biscuitrnrespectively.rnRegarding to profitability, gross earning will be 46,200,000birr, ROI = 26.84%, pay backrnperiod = 3.2 year and break even point = 17.54%