Title
Structural and emulsifying properties of sodium caseinate and lactoferrin influenced by ultrasound process
Author
Guilherme de Figueiredo Furtado, Raphaela Araújo Mantovani, Larissa Consoli, Miriam Dupas Hubinger, Rosiane Lopes da Cunha
Year
2017
Journal
Food Hydrocolloids
Abstract
Structural, physical and emulsifying properties of sodium caseinate and lactoferrin were investigated after these proteins were subjected to ultrasound treatment. Aqueous sodium caseinate or lactoferrin solutions were sonicated for 2–6 min using a power of 300 W. Protein properties as size, surface charge, molecular weight distribution, intrinsic viscosity, surface hydrophobicity and structural conformation from circular dichroism were evaluated. Sodium caseinate size was significantly reduced after ultrasound treatment while an opposite effect was observed for lactoferrin. Slight differences in molecular weight after ultrasound treatment were observed only for lactoferrin. Intrinsic viscosity and surface hydrophobicity was positively affected by the increase of sonication time. Circular dichroism spectra revealed no differences for sodium caseinate structure but slight changes were observed for lactoferrin. In addition, a fixed amount (1 wt%) of this ultrasound-treated protein was employed as an emulsifier to prepare oil in water emulsions (o/w). Emulsions were also produced using the same ultrasound conditions that aqueous protein solutions were subjected. They were evaluated in terms of droplet size, emulsifying activity, creaming index and emulsion stability. Emulsions showed reduced droplet size and improved stability with higher sonication times. Coarse emulsions stabilized by ultrasound-treated proteins showed a slightly higher stability when compared to coarse emulsions stabilized by non-treated proteins. However, completely stable emulsions were produced only by ultrasound emulsification of coarse emulsions, suggesting that the protein changes occurring simultaneously to the droplets size reduction contributed to the enhancement of emulsifying properties.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Food science, Biochemistry