The enhancement of gastrointestinal digestibility of β‐LG by dynamic high‐pressure microfluidization to reduce its antigenicity

Impact of pilot-scale microfluidization on soybean protein structure in powder and solution

The effect of microfluidization treatment on the primary, secondary, and tertiary structure of soybean protein isolate (SPI) was investigated. The samples were treated with and without controlling the temperature and circulated in the system 1, 3, and 5 times at high pressure (137 MPa). Then, the treated samples were freeze-dried and reconstituted in water to check the impact of the microfluidization on two different states: powder and solution. Regarding the primary structure, the SDS-PAGE analysis under reducing conditions showed that the protein bands remained unchanged when exposed to microfluidization treatment. When the temperature was controlled for the samples in their powder state, a significant decrease in the quantities of β-sheet and random coil and a slight reduction in α-helix content was noticed. The observed decrease in β-sheet and the increase in β-turns in treated samples indicated that microfluidization may lead to protein unfolding, opening the hydrophobic regions. Additionally, a lower amount of α-helix suggests a higher protein flexibility. After reconstitution in water, a significant difference was observed only in α-helix, β-sheet and β-turn. Related to the tertiary structure, microfluidization increases the surface hydrophobicity. Among all the conditions tested, the samples where the temperature is controlled seem the most suitable.

High-pressure microfluidization of whey proteins: Impact on protein structure and ability to bind and protect lutein

Dynamic high-pressure homogenization microfluidization (DHPM) is a versatile emerging technology that may be applied to food processing to achieve several goals. DHPM may, depending on nature of the molecules and the working parameters, induce changes in protein structure, which may improve or impair their techno-functional properties and ability to bind other molecules. In this context, DHPM (12 passes, 120 MPa), coupled or not to a cooling device, was applied to β-lactoglobulin (β-lg) and whey protein isolate (WPI) dispersions. Minor changes in the structure of whey proteins were induced by DHPM with sample cooling; although, when sample cooling was not applied, aggregation and increases of around 30% of protein surface hydrophobicity were noticeable for the WPI dispersion. The association constant between the proteins and lutein was in the magnitude of 10⁴ M^-1, and lutein photodegradation constant diminished about 3 times in the presence of proteins, compared to in their absence.

Modulation of the structural and functional properties of perilla protein isolate from oilseed residues by dynamic high-pressure microfluidization

Dynamic high-pressure microfluidization (DHPM) is an alternative method to physically modify proteins to improve their functional properties. In this study, perilla protein isolate (PPI) was treated by DHPM at different pressures. Results showed that DHPM treatment reduced the particle size and absolute potential of PPI by 75.90% and 22.28%. The increased surface hydrophobicity and free sulfhydryl content were observed in DHPM-treated PPI, which may be caused by the comformation changes of PPI. Furthermore, DHPM treatment would not cause the degradation of the main subunits and the variation of crystalline regions in PPI, but enhancing the thermal stability of PPI at 90 MPa and 120 MPa. Functional properties analysis indicated that DHPM treatment at 120 MPa was more effective in improving the solubility, foaming and emulsifying capacities of PPI. The results suggested that DHPM can be used to enhance the functional properties of PPI and expand its application in food systems.

Latest developments in the applications of microfluidization to modify the structure of macromolecules leading to improved physicochemical and functional properties

Microfluidization is a unique high-pressure homogenization technique combining various forces such as high-velocity impact, high-frequency vibration, instantaneous pressure drop, intense shear rate, and hydrodynamic cavitation. Even though it is mainly used on emulsion-based systems and known for its effects on particle size and surface area, it also significantly alters physicochemical and functional properties of macromolecules including hydration properties, solubility, viscosity, cation-exchange capacity, rheological properties, and bioavailability. Besides, the transformation of structure and conformation due to the combined effects of microfluidization modifies the material characteristics that can be a base for new innovative food formulations. Therefore, microfluidization is being commonly used in the food industry for various purposes including the formation of micro- and nano-sized emulsions, encapsulation of easily degradable bioactive compounds, and improvement in functional properties of proteins, polysaccharides, and dietary fibers. Although the extent of modification through microfluidization depends on processing conditions (e.g., pressure, number of passes, solvent), the nature of the material to be processed also changes the outcomes significantly. Therefore, it is important to understand the effects of microfluidization on each food component. Overall, this review paper provides an overview of microfluidization treatment, summarizes the applications on macromolecules with specific examples, and presents the existing problems.