Studies On Preparation, Physicochemical Properties And Bioactivities Of Corn Peptides

Com is not only one of the three most impotant cereals but also an important feedstuff. For high output and large increasing potential, corn plays an important role in angriculture production. Corn is made up of starch, protein, little water, ash, fat and so on. Starch is an important component in corn, while CGM (Corn gluten meal) is the main byproduct after extracting starch from the corn, having about 60% protein. Because of its bad taste, poor water-solubility and nutrition, application of CGM was limited in food industry. Now researches in CGM re-utilizing in our country is on primary phase. Choosed CGM as the material in this experiment, preparation of Corn peptides, purification, physicochemical properties and bioactivities of Corn peptides were studied, in order to enhance its value, improve its physicochemical properties, and reduce environment pollution as well. The main results were shown as follows:1 Preparation of Corn peptidesEffects of the density of substratum, pH, the amount of protease and hydrolysis temperature of inhibition ability of Corn peptides to hydroxyl radicals(·OH) were studied, and the optimum conditions were determined by singal factors and orthogonal experiment, The optimum technology conditions are: the density of substratum 4%, pH 9.5, the amount of protease 1000u/gCGM and hydrolysis temperature at 55℃for 4 hours. The receiving ratio of coarse Corn peptides was 56.21%, which contains 52.68% protein. After desalting with DA201-C macroporous adsorption resin, the receiving ratio of Corn peptides was 43.96%, which contains 82.69% protein.2 Physieoehemieal properties of Corn peptidesDissolvable ability, viscoce property, foaming characteristics and foam stability, oil-adsorbing ability, molecular weight, amin acid composing of freeze drying production of Corn peptides were studied. The physicochemical properties of CGM were improved obviously by enzymic hydrolysis. Corn peptides were separated into two components: CP-1 and CP-2, accounting for about 5.91% and 75.12%, and the molecular weight of Corn peptides was about 1000D. The essential amino acid such as Thr, Met, Ile, Phe increased after enzymolysis.3 Antioxidant activity of Corn peptidesThe K₃[Fe(CN)₆] was used to evaluate corn peptides' capacity of deoxidizing; using the DNA-Fe system, superoxide radical(O^2-·) system and the DPPH system·, the antioxidation activities of corn peptides were studied; the reagent kits were used to analyse the content of malondialdehyde (MDA) in mice liver homogenate and mice liver mitochondria; using spectrometer to evaluate hemolysis of mice red blood cell and swelling of mice liver mitochondria. The results showed that Corn peptides was a good reducer and had evident inhibiting effects on free radical of·OH, DPPH·, O^2-·; in vitro, the inhibiting rate of 10.00mg/mL Corn peptides on radical-induced MDA formation was 39.63% in mice liver mitochondria, while 22.82%(without incubation), 45.59%(incubation with Fe²⁺) and 67.53%(incubation with H₂O₂) in mice liver homogenate; Corn peptides made the radical-induced swelling of mice liver mitochondria much lower than that of mice liver mitochondria without inducement; Corn peptides could inhibit hemolysis induced by H₂O₂ of rat red blood cell, which showed protection activity against oxidation damage of rat red blood cell, but not obviously without incubation.4 Antitumor effects of corn peptides in vivoTake physiological salt as normal control group, the Cy, the lower dose of Corn peptides, the medium dose of Corn peptides, the higher dose of Corn peptides as the test teams, the index of body weigh, lumor weigh, thymus weigh, spleen weigh, the MDA content, the power of GSH-PX and SOD were studied, and then the tumor cells configuration were analyzed. The results showed that the different amount of Corn peptides teams exhibited different tumor-inhibiting effects. The body weigh, the immunity apparatus weigh of Cy team were obviously different from those of normal control group, while those of Corn peptides teams were slightly different. It was infered that Corn peptides could inhibit the tumor through improving the mice immunity.