Physicochemical and functional properties of the protein isolate and major fractions prepared from Akebia trifoliata var. australis seed

The physicochemical and functional properties of protein isolate (API) and major protein fractions prepared from Akebia trifoliata var. australis seed were investigated. The seed contained 38.83% of oil and 17.23% of protein. Albumin (51.65%) and glutelin (46.40%) were the predominant fractions in the protein component of the seed. The major amino acids were found to be glutamic acid and aspartic acid, while the contents of sulphur-containing amino acids and threonine were very low. One to eight distinct bands with molecular weight (MW) ranging from 12.0 to 50.0 kDa were displayed by SDS–PAGE. The solubilities of API, albumin and glutelin from seeds of the A. trifoliata var. australis were the lowest at pH 4.0–5.0. The high surface hydrophobicity indices of these three proteins were observed at pH 7.0, while the excellent emulsifying properties were displayed at pH 9.0. Circular dichroism measurements indicated that API, albumin and glutelin were rich in β-strand and random coil structures.