Ionic liquid extraction of silkworm pupa protein and its biological characteristics

Abstract

• A novel extraction method for silkworm pupa protein has been demonstrated. • The CH-IL extraction increased protein content by 12.14%. • The solubility, emulsification, and foaming capacity of the CH-IL extracted protein were enhanced. Silkworm ( Bombyx mori ) pupa protein (SPP) is a high-quality source of animal protein with substantial nutritional benefits and health value. To develop an efficient extraction method for SPP that is environmentally friendly, we selected choline hydroxide ionic liquid (CH-IL) as the extraction solvent and performed orthogonal experiments to optimize the extraction conditions. We demonstrated that 3% CH-IL, a solid-to-liquid ratio (g/mL) of 1:30, an extraction temperature of 40 °C, and an extraction time of 1 h facilitated the most efficient extraction. Compared to the conventional alkali solubilization–acid precipitation method, the CH-IL extraction increased protein content by 12.14%. Protein structure analysis showed that the β-sheet content increased by 10.98% and that of disulfide bonds reduced by 16.4%. The processing properties of the CH-IL extracted protein showed that the solubility, emulsification, and foaming capacity were enhanced by 82.87%, 15.44%, and 18.97%, respectively. The physical properties of SPP remarkably improved relative to the increased stretching of the polypeptide chains. The findings of this study provide technical knowledge that will enhance the processing performance of pupal proteins.