Comprehensive Utilization Of Buckwheat Bran

Buckwheat is nutrient-rich, there are much proteins, dietary fibers and starch in its bran.The comprehensive utilization of buckwheat bran in appropriate way can not only improve the utilization rate of buckwheat effectively, increase the added value of buckwheat, but also promote the economic growth of planting areas.In this study, buckwheat bran from shaanxi yulin was selected as raw material. The extraction and color-protecting of protein from buckwheat bran was studied firstly. Then insoluble dietary fibers and the starch sugar were extracted by enzymatic method from residue. The main research contents and conclusions were as follows:1. The protein was extracted from buckwheat bran by alkaline hydroiysis and salt solvent method respectively. The results showed: the isoelectric point(PI) of protein in alkaline solution was 3.8, and the optimal extraction parameters of alkaline hydroiysis were: p H10.5, extraction time 4h, ratio of solid to liquid 1:25, extraction temperature 45℃, the extraction yield of protein under the optimum conditions was 70.50%. The isoelectric point of protein in salt solution was 4.2, the optimal extraction parameters of salt solvent method were: p H7.8, NaCl concentration 0.3mol/L, ratio of solid to liquid 1:20, extraction temperature 45℃, extraction time 1.5h, the extraction yield of protein under the optimum conditions was 57.30%.2. The protein was extracted from buckwheat bran by ultrasound-assisted with alkaline hydroiysis. The p H, ratio of liquid to solid, extraction time and ultrasonic power were investigated by single factor and orthogonal experiment. The results showed that the order of factors influenc ing protein’s extraction yield was: p H > ultrasonic power > ratio of liquid to solid > extraction time. The optimum conditions were: p H10.5, ratio of liquid to solid 25:1, extraction time 3 h, ultrasonic power 250 W, the extraction yield of protein under the optimum conditions was 77.80%.3. The color-protecting conditions of protein extracted above were studied.The results showed that ascorbic acid had better effect on buckwheat bra n protein. The optimum add ition of ascorbic acid was 0.08%, and decoloriz ation rate was 60.56%, with the loss rate 19.43%.4.The characteristics of buckwheat bran protein was studied. The results showed: the oil holding capacity of the protein was higher when the protein partiele of 100 mesh size and 80℃separately. The water holding capacity of the protein was higher when the protein partiele of 100 mesh size and 40℃separately. The solubility, emuls ification, foaming ability of the protein was all better at 40℃, and reached 56.18%,81.82%,56.4% separately. The emuls ion stability of the protein was 92.78% with sucrose concentration 2%, and the foam stability reached 67% at 4 ℃. The results of Hitachi amino acid analyzer showed that: total content of amino acid was 791.98mg/g, essential amino acid content was 297.10mg/g, accounted for 37.51% of total amino acids.5. The preparation of insoluble dietary fibers and starch sugar was studied with the residue after protein extraction. The optimum preparation conditions of insoluble dietary fiber were: ratio of solid to liquid 1:3, enzymolys is time of α-amylase 20 min, addition of α-amylase 0.83%. The yield of insoluble dietary fiber was 28.61%, and the liquefaction DE was 27%. The optimum saccharification conditions of starch sugar were: enzymolys is time 48 h, addition of glucoamylase 0.3%, temperature 60℃. The DE value under the optimum condition was 96%.6. The characteristics of insoluble dietary fibers extracted from sweet buckwheat bran residue was investigated. The results showed that oil holding capacity, water holding capacity and swelling ability of insoluble dietary fibers were better when the insoluble dietary fibers partiele of 100 mesh size and 80℃separately.