Chinese quince seed proteins: sequential extraction processing and fraction characterization

Chinese quince seed proteins were sequentially extracted based on the modified Osborne method. Investigations showed that albumin and glutelin were the major fractions. The physicochemical and functional properties of these two fractions were determined. The results showed that both albumin and glutelin posed appropriate essential amino acid composition and met the minimum recommendation (World Health Organization/Food and Agriculture Organization) for adult diet, except for methionine. The hydrophobicity of albumin and glutelin were 1063.56 and 1170.21, respectively. According to differential scanning calorimeter analysis, the denaturation temperature of albumin and glutelin was 101.44 °C and 108.36 °C respectively, and the glutelin fraction had a better thermal stability. The solubility and apparent viscosity of albumin and glutelin were presented to be greatly influenced by pH values. The water holding capacity and oil adsorption capacity of glutelin were 5.44 g/g and 8.15 g/g, higher than those of albumin which were 3.76 g/g and 3.71 g/g, respectively. Circular dichroism determination revealed albumin and glutelin were mainly composed by α-helix and random coil structures. Albumin and glutelin presented the potential as favorable nutrition and functional additive in food industries.