| The technology of Buckwheat starch extracting was created by simulating the common technology of starch extracting from other grains and the technical parameters were studied. The crude Buckwheat starch was purified by alkali solution and acid solution washing, which decreased quantity of proteins and ashes respectively. The qualitative indexes of the separated Buckwheat starch were analyzed. The gelatinization characters were analyzed. And the results were compared with three kinds of first class edible starch. The techniques of preparing Buckwheat starch acetate and Buckwheat carboxyl-methyl starch were studied also.The result of material components analysis suggested that Buckwheat grain contains 13.96% water, 69.02% starch,12.74% proteins, 2.24% fats and 1.64% ashes.The optimum technique parameters of extracting Buckwheat starch were as follows: for steeping, Buckwheat grain dipped 2h at 55℃ and the concentration of sulfur dioxide in steeping solution was 0.24%; for wet-milling, the weight ratio of water to material was 11:1, the mill repeating time was 9; for crude starch separating, after the Buckwheat thick liquid being filtered impurity with 200 sifts and naturally precipitated, the crude starch was extracted. The result showed that the starch extraction rate from Buckwheat grain was 87.85%. The optimum technique condition of purifying crude Buckwheat starch were as follows: the pH value of alkali lotion was 11, the weight ratio of alkali lotion to crude starch was 11:1, rinsing time was 3; the pH value of acid lotion was 2, the weight ratio of acid lotion to crude starch was 11:1, rinsing time was 1. The result showed that the contents of protein and ash in the product were 0.48% and 0.15% respectively. Study on technique of bleaching Buckwheat starch showed that the best bleacher was H2O2, whose dosage was 0.06 g/kg, the white degree of final product was 94.The qualitative indexes analyzing showed that the final separated Buckwheat starch product were equal to or even superior to these of first class edible starch. The separated Buckwheat starch contained 23.87% ( dry weight ) amylose. Its gelatinization temperature(GT) of Buckwheat starch was equivalent to that of wheat starch, but was higher than that of maize starch and potato starch. Its heat stability of viscosity was remarkably stronger than that of wheat starch, maize starch and potato starch, but its cold stability of viscosity was the feeblest. Its gelatification was more powerful than these of potato starch, and less powerful than those of wheat starch and maize starch. Its precipitation was more powerful than these of potato starch and slightly feebler than that of wheat starch. Its transparency was markedly inferior to that of potato starch and wasequal to those of wheat starch and maize starch. Its stability of freezing and melting was equal to that of wheat starch and maize starch, but was inferior to that of potato starch.The optimum technology parameters of Buckwheat starch acetate contained 2.5% acetyl, were as follows: the concentration of Buckwheat starch was 40%, the mol ratio of acetic anhydride to starch was 1:10, the concentration of NaOH was 0.2%, the pH value was 7.5, and modifying process was conducted for 90min at 25℃. The optimum conditions of preparing Buckwheat carboxyl-methyl starch(CMS) whose substitution degree(DS) was 0.3 were as follows: the concentration of starch was 30%, and that of water was 30% also, the mol ratio of monochloroacetic acid to starch was 0.5:1, the mol ratio of NaOH to starch was 0.35:1, and modifying process was conducted for 6h at 50 ℃.Study on application of Buckwheat starch and modified Buckwheat starches showed that Buckwheat CMS was suitable to manufacture instant soup, and it could substitute expensive imported special modified starch. |
PDF Full Text Request