Composition And Structure Of Phytate Containing Globoids Isolated From Defatted Rice Bran

This study was based on an interesting kind of white compounds after the def-fated rice bran was treated with several polysacharidases. After preliminary analysis, it was demonstrated that there was a high phytate content in the white compounds. Meanwhile, according to the previous research about aleurone grains containing a high level of phytate, two different isolation methods were employed to extract the white compounds. Then the trail was conducted to evaluate the chemical composition and the ultrastructures of these white compounds. After that, the white compounds were per-hydrolysesed by phytase or hydrochloric acid, respectively. And then the hydrolyzate was separated by prep-HPLC, the chemical composition and structure of the separated constitutes were determined by LC-MS and31P NMR for the further in-vestigation of the phytate containing globoids.Experiment1:Isolated the white compounds and dertermined the conven-tional ingredients Mutilenzyme combination treatment (Method A, MA) and dex-tran-polyethylene glycol phase system (Method B, MB) were employed to extract the white compounds mentioned above from the defatted rice bran, respectively. The minerals, amino acids, monosaccharides, and phytate acid contents in the white com-pounds by the two methods were quantitated. Results showed that the contents of phytic acid in the white compounds extracted by MA and MB were27.26%and22.06%on a dry matter basis, respectively. High concentrations of calcium, magnesium, po-tassium, Asp, Glu, Arg, Leu, Gly, Ala, glucose, xylose and arabinose were found in the extracts based on MA and MB.Experiment2:Microstructure of the white compounds The ultrastructures of these compounds extracted by the two methods, defatted and puffed rice bran were examined by scanning electron microscopy. The electron microscopic photos revealed that there were two kinds of globoids differentiated from their particle diameters in rice bran; the bigger one was about6.00μm, while the small one is about2.06μm. After puffed with rice bran, there was no globoid found in the position it was sup-posed to be. Specifically, the white compounds extracted by MA are composed by a series of transparent particles with their diameters ranged form1-4μm, and the surface of these particles was smooth. In contrast, the particle sizes of the white compounds extracted by MB were ranged from1-3μm, and they were consisted of these particles, starch and cell wall residue. In summary, the white conpounds extracted ethier by MA or MB are both ball-shaped, and rich in phytate, as it can be concluded that the par-ticles isolated by MB we detected are phytate-containing globoids.Experiment3:The structure and composition of the phytate-containing glo-boids The white compounds extracted by mutilenzyme combination treatment was per-hydrolysesed by phytase or0.01M hydrochloric acid, respectively, and then the representative hydrolyzate was separated by prep-HPLC. Then the contents of amino acids and monosaccharides were determined in the separated constitutes. Further more, the molecular weight and the position of P in these constitutes were analyzed by LC-MS and31P-NMR, respectively. Results showed that:the components of hydro-lysate of phytate containing globoids isolated by MA by phytase are rich in Glu, Gly, Leu, rhamnose, arabinose, and glucose. The components of hydrolysate of phytate containing globoids isolated by multienzyme combination by0.01M hydrochloric ac-id are rich in Asp, Glu, Gly, Ala, rhamnose, ribose, and glucose. Compare with the treatment by0.01M hydrochloric acid, phytase can hydrolyze phytate-containing globoids into smaller molecules.Meanwhile, phytase release phosphate groups from the phytate containing globoids.0.01M hydrochloric acid can hydrolyze the ester bond of the phytate containing globoids but can not release phosphate groups.