Modification of foaming properties of soy protein isolate by high ultrasound intensity: Particle size effect

Abstract

The effect of high intensity ultrasound (HIUS) may produce structural modifications on proteins through a friendly environmental process. Thus, it can be possible to obtain aggregates with a determined particle size, and altering a defined functional property at the same time. The objective of this work was to explore the impact of HIUS on the functionality of a denatured soy protein isolate (SPI) on foaming and interfacial properties. SPI solutions at pH 6.9 were treated with HIUS for 20 min, in an ultrasonic processor at room temperature, at 75, 80 and 85°C. The operating conditions were: 20 kHz, 4.27 ± 0.71 W and 20% of amplitude. It was determined the size of the protein particles, before and after the HIUS treatment, by dynamic light scattering. It was also analyzed the interfacial behavior of the different systems as well as their foaming properties, by applying the whipping method. The HIUS treatment and HIUS with temperature improved the foaming capacity by alteration of particle size whereas stability was not modified significantly. The temperature of HIUS treatment (80 and 85°C) showed a synergistic effect on foaming capacity. It was found that the reduction of particle size was related to the increase of foaming capacity of SPI. On the other hand, the invariable elasticity of the interfacial films could explain the stability of foams over time.

Modification of Foaming Properties of Commercial Soy Protein Isolates and Concentrates by Heat Treatments

“…Furthermore, the high intensity ultrasound (HIUS) treatment and HIUS with temperature improved the foaming capacity by alteration of particle size whereas stability was not modified significantly (Morales et al . ). The temperature of HIUS treatment (80C and 85C) show a synergistic effect on foaming capacity, and the reduction of particle size was related to the increase of foaming capacity of SPIs.…”

Improved Functionality of Foamed WPI Solutions by Ultrasound Application

“…Time of sonication was selected conforming previous studies at different times [7] and was chosen the time where more pronounced was the HIUS effect on foaming properties.…”

“…It may cause physical changes on proteins producing aggregates through non-covalent bonds by cyclic generation and collapse of cavities depending of structural and protein state aggregation [7].…”

The role of casein micelles and their aggregates in foam stabilization

“…Recently particles including hydrogel protein particle, capsules, protein aggregates and polymer fibres etc. have received considerable attention [45][46][47][48][49], which could be promising in application of foods and drug delivery mediums. These particles would greatly extend the types of particles that can influence the thin film properties which are so important to the foam stabilisation mechanisms.…”

“…Previous research has shown that the presence of aggregates can have a large influence on foam stability of protein solutions [42]. Whey protein aggregates [36,37,43], soy protein aggregates [44,45] whey protein fibrils [38,46] and whey protein microgel [47,48] were shown to be advantageous for foam stabilization, while other studies indicated that protein aggregates can also decrease foam stability [41,43]. The aggregate size resulting in higher foam stability varied for different aggregated materials and their structure [41,43].…”