Study On Extracting Flavonoids From Buckwheat Hulls

Extracting flavonoids in buckwheat hulls by supercritical carbon dioxide and alcohol-water system were studied. Single factor experiment and orthogonality experiment were applied to find the relationship between total flavonoids and several factors. The ability of two flavonoids solution to remove nitrite was compared. The results showed that the optimum extracting rate of supercritical CO2 extraction was obtained at solid-liquid ratio of 1:10, extracting temperature of 35℃, extracting pressure of 25 MPa ,and extracting time of 4 hours. The optimum extracting rate of alcohol-water system was obtained at solid-liquid ratio of 1:30, the solution of alcohol of 40%, temperature of 80℃, and extracting time of 5 hours. When pH was in the range of 3 to 7, the capability of eliminating NO2－ of two flavonoids solution was different. Under the same condition, supercritical CO2 extracting solution could get higher nitrite elimination quickly. When the condition was similar to the temperature and pH of man's gastric, that was 37 ℃, pH 3, removal ratio of supercritical CO2 extracting solution and alcohol-water system extracting solution were 70.63% and 80.63% respectively.