Title
Ultrasound improving the physical stability of oil-in-water emulsions stabilized by almond proteins
Author
Zhenbao Zhu, Cui Zhao, Jianhua Yi, Leqi Cui, Ning Liu, Yungang Cao, Eric Andrew Decker
Year
2018
Journal
Journal of the Science of Food and Agriculture
Abstract
Vegetable proteins are increasingly used to stabilize oil-in-water (O/W) emulsions. However, emulsions are thermodynamically unstable. Recently, high-intensity ultrasound (US) has been used to enhance the stability of emulsions. For these reasons, and considering almond (Prunus dulcis L.) is a good source of high quality proteins, the aim of the work was to investigate the effect of US treatment on the stability of pre-emulsification O/W emulsions coated by almond protein isolate (API). The influence of API concentration (0.25-2.0 g L-1), ion strength (0-500 mmol L−1 NaCl), and pH (3.0-7.0) on the stability of US-treated emulsions was evaluated. US treatment (200-600W, 25 kHz, 15min) led to significant reduction in the particles size of droplets in emulsions, increased critical osmotic pressure and additional protein interfacial adsorption, and thus the formation of more stable emulsions. The proteins unfolded and more random coil was detected at higher US power, facilitating protein interfacial adsorption. Increasing API concentrations resulted in higher stability of US-treated emulsions against untreated counterparts. The US-treated emulsions were more resistant to salt than untreated samples. In the range from pH 3.0 to7.0, US treatment also enhanced the physical stability of emulsions compared with untreated emulsions. US technology could be applied to produce more stable O/W food emulsions stabilized by proteins.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Biochemistry, Food science