| Main storage protein fractions were extracted from defatted common buckwheat (Fagopyrum esculentum Moench) in Inner Mongolia and purified by salting-out and anion-exchange chromatography and analyzed by SDS–PAGE in order to determine the structures and functional properties of protein fractions. Optimum conditions of main storage protein fractions extracted by Osborne method were determined by single-factor experiment and orthogonal experiment: condition of albumin were dosage liquor ratio 1∶12, extraction time 35 min, condition of globulin were NaCl concentration 10%, dosage liquor ratio 1∶12, extraction time 35 min, and condition of glutelin were NaOH concentration 0.4%, dosage liquor ratio 1∶12, extraction time 25 min. Optimum extraction time was 4 which has 90% extraction rate. Protein fractions component analysis showed total proteins content accounted for 15% of buckwheat flour. Albumin, globulin and glutelin accounted for 42%, 32% and 22%, respectivity. Salting-out curves showed that saturation degree of albumin, globulin and glutelin were 100%, 80% and 70%, respectivity. SDS–PAGE analysis indicated that albumin showed major bands at 43,31,15 kDa, and globulin had bands at 31,33 kDa. Storage proteins had minimum solubilities at pH 4.5 and solubility of globulin which reached 40% was best. Emulsify activity of globulin was 80.6 m2/g which was higher than glutelin (21.2 m2/g) and albumin (18.9 m2/g). Emulsify stability showed that globulin (25.0 min) was better than glutelin (18.0 min) and albumin (13.3 min). Foamability of globulin was 72.3%, and that of glutelin (68.2%) was next. 30 min and 60 min foam stability results showed that globulin was better than glutelin and albumin.
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