Study On The Extraction Of Dietary Fiber. Protein From Prickly Ash Seed And Preparation Of Antioxidation Peptide

Prickly ash seed is the by-products of pepper sauce. The seeds contain plentiful grease、 crude fiber and protein. The greaves which left after exploiting the oil are the high-quality raw materials to extract natural dietary fiber and protein. This thesis studied on the constituent compositions of prickly ash seed, the extraction of dietary fiber and protein, and discussed their functional characteristics, then prepared antioxidant peptide using protein extracted. The main research results are as follows:1. The compositions of prickly ash seed were determined and the results indicated that there was high content of grease(13.50%), protein(11.35%) and insoluble dietary fiber(48.93%).2. The Box-Behnken experimental design was used to optimize extraction processing of insoluble dietary fiber and soluble dietary fiber. The optimum processing conditions of insoluble dietary fiber extraction were alkaline treatment concentration3.17%, alkaline treatment temperature49.94℃, alkali treatment time40.86min, the consumption of trypsin0.4%. Under the optimized conditions, the extraction yield of insoluble dietary fiber was80.58%. Insoluble dietary fiber extracted was dark-gray and contained plenty nature melanin. Its WHC and expansibility are lower than other dietary fiber. The extractions of soluble dietary fiber from prickly ash seeds using enzymatic method, chemical method, enzymatic method under pressurized pre-treatment and chemical method under pressurized pre-treatment were investigated. The optimum processing conditions of enzymatic method were solid to liquid ratiol:22.76, temperature41.90℃, time13.02h, pH4.33. Under the conditions, SDF yield was9.20%. The optimum processing conditions of chemical method were pH2.50, temperature79.49℃, time1.2h and solid to liquid ratio1:14.18. Under the conditions, SDF yield was12.31%. The optimum processing conditions of enzymatic method under pressurized pre-treatment were pressure temperature117.02℃, pressure pH6.02, pressure time1.2h. Under the conditions, SDF yield was16.35%%. The optimum processing conditions of chemical method under pressurized pre-treatment were pressure temperature117.73℃, pressure pH6.13, pressure time95.41min. Under the conditions, SDF yield was21.73%. It can seen that SDF yield of chemical method is higher than enzymatic method, the optimal extraction yield under pressurized pre-treatment of chemical method and enzymatic method were77.17%、76.52%above that of extraction under atmospheric pressure, which confirmed that pressurized pre-treatment could obviously improve the extraction yield of SDF yield.3. The second-order regression rotation design was used to optimize extraction processing of protein, and molecular weight and functional-properties of protein were explorated. The optimum processing conditions of protein extraction were pH6.40, temperature51.30℃, time13.02h, solid to liquid ratio1:25.00, the dose of protease5.43%. Under the conditions, protein yield was77.21%%. The molecular weight of the protein extracted from prickly ash seeds are about21.5KDa、33.0KDa. The solubility of protein extracted from prickly ash seeds was lowest when pH was4; when the temperature was45℃, and NaCl concentration was0.6mol/L, the protein showed the highest solubility. WHC of the protein extracted from prickly ash seeds decreased with the increase of the temperature; WHC of the protein was highest when pH was6and NaCl concentration was0.6mol/L. Foaming ability and foaming stability of the protein extracted from prickly ash seeds increased with the increase of the protein concentration. When pH was4, both of them were lowest; foaming ability was strongest when NaCl concentration was1.0mol/L. The foaming stability of protein increased while NaCl concentration increased. Emulsifying property and emulsifying stability of protein extracted from prickly ash seeds increased with the increase of the protein concentration and decreased with the increase of NaCl concentration. Both of them is lowest when pH was4.4. The optimum protease of antioxidant peptide preparation of prickly ash seed was Alcalase2.4L protease. The optimum processing conditions of antioxidant peptide preparation using Alcalase2.4L protease were substrate concentration5%, temperature55.00℃, pH8.5, the dose of protease4.00%. Under the optimized conditions, DPPH·scavenging activity was61.17%, and DH was12.16%.