Effects of different milling methods on the physicochemical properties of tartary buckwheat leaf powder

ObjectiveThe effect of milling methods on tartary buckwheat leaves was discussed.MethodsTartary buckwheat leaves（Heifeng 1） were used as raw materials and the effects of the different grinding treatments (electric stone mill, ultra-microcrushing, steel grinding, grainmill) on the physical-chemical characteristics such as particle size, specific surface area, density, angle of repose, nutrient composition and hydration characteristics of tartary buckwheat leaf powder were investigated.ResultsThe contents of protein-soluble dietary fiber, chlorophyll and functional components GABA, rutin and quercetin in tartary buckwheat leaf powder prepared by ultrafine grinding were significantly higher than those of other methods. The particle size of tartary buckwheat leaf powder was small when prepared by the electric stone mill, followed by ultrafine grinding, and the color was the brightest. The D50 was three to five times more than that of previous grinding techniques, the specific surface area and cell breakage rate were the lowest, and the fluidity was the highest after the grains were ground. The water-holding capacity of grain mill leaf powder was the highest, and the water solubility was the lowest. At room temperature, the swelling property of tartary buckwheat leaf powder decreased with the decrease in powder particle size. Fourier transform infrared spectroscopy analysis showed that the infrared absorption spectra of tartary buckwheat leaf powder by four milling methods were the same, all of which contained O—H, C—H, C=O, N—H and C—O—C bonds.ConclusionDifferent grinding methods affect the characteristics of tartary buckwheat leaf powder, and the grinding method can be selected according to the terminal use. Among them, ultrafine grinding has the best retention of functional components of tartary buckwheat leaf powder.