Study On Preparation Of Protein Peptide And Phytic Acid From Defatted Rice Bran

This paper overviews the nutritional function, current application, and thetechnology of extraction of rice bran protein and phytic acid, and analyzes theadvantages and disadvantages of present extraction methods. On this basis, a feasibleprocess route was designed. The main idea of this process route included four parts:First step was directly to extract protein from defatted rice bran, so that protein can beisolated from other compounds, which avoided them generating poly-compounds again.Second step was the usage of membrane technology，which raised the purification effectof protein. Third step was to extract phytic acid from rice bran meal and fourth was thepurification of phytic acid with ion exchange resin.The main contents and results are as follows:(1) Enzymatic extraction conditions for protein from defatted rice bran werestudied.On the basis of fully soaking and grinding, the single factor tests andBox-Behnken experimental design was used to investigate the effects of liquid-solidratio, pH, temperature and enzyme dosage. The experimental result showed theexperimental optimum conditions were determined by alcalase concentration1.1%，liquid-solid ratio10：1，pH=8.5，temperature55℃.Under these conditions，theextraction rate reached63.06%.(2)Membrane device for the purification and concentration of protein solutions waschosen.Microfiltration(MF) was used to the removal of impurities such as suspendedparticles and macromolecular bacteria in the solutions.The operation was in theconditions of room temperature,0.2MPa pressure and full cycle running.Thennanofiltration(NF) was used to the removel of saline ions of filtrate of MF. Theoperation conditions were room temperature,1.5MPa pressure and full cycle running.The salt rejection rate reached84.4%and the concentrate factor was19.3times.Vacuum freeze drying was used to drying of concentrated solutions of NF. The finalprotein powder was selected and its color presented light yellow and white, watercontent was less than5%, and purification reached89.6%.(3) Extraction conditions for phytic acid from rice bran meal were studied. Theeffects of some factors such as liquid-solid ratio, pH, temperature and extraction timewere investigated. The optimal conditions were as follows: liquid-solid ratio is10:1,pH=2, temperature is55℃, extraction time is2h. Under this condition, the extractionrate reached81.7%and purification reached88.4%.(4) D311, D301and2017resins for phytate adsorbent properties were comparedand2017resin was selected for the coming experiment. Static and dynamic methodsfor adsorption and desorption by2017resin were investigated. The results showedthat: in the static adsorption experiment, the temperature has little effect on theadsorption of this resin, dilution of solution concentration can slightly improves theadsorption, and adsorption is weakened with pH rising in acidic range. In dynamicexperiments, considering adsorption and desorption effect and the cost of solvent, theflow rate and concentration of sample solutions and elution solvents were investigated.And the optimum conditions were:1mL/min and8mg/mL of samle flow rate andconcentration,1mL/min and2mol/L of flow rate and concentration of NaOH solutionas elution solvents. (5) Anti-oxidation characteristics of phytic acid were tested. The results showedthat: phytic acid added to the lard will increase slightly its acid value, but phytic aciditself has oxidation resistance in rancidity process, which can suppress the generation ofperoxide, so as to reduce the peroxide value and carbonyl value of lard. In addition, asradicals scavenging substance, phytic acid can clear out hydroxyl radicals(OH)effectively, the higher concectration of phytic acid, the stronger scavenging activity to(OH).