Structural Assessment and Catalytic Oxidation Activity of Hydrophobized Whey Proteins

Interventional effect of compound sugar and salt on the thermal instability behavior of liquid egg yolk

In this study, the influence of compound sugar (glucose, sucrose, trehalose, and arabinose) and compound sugar and salt (glucose, sucrose, trehalose, arabinose, and NaCl) on the thermal stability of heat-treated liquid egg yolk was explored. The results showed that the addition of 4% compound sugar or 4% compound sugar salt could significantly enhance the heat resistance of liquid egg yolk and increase the denaturation temperature of liquid egg yolk to above 77°C. Moreover, the addition of sugar and salt could improve the functional properties of liquid egg yolk to varying degrees, allowing it to maintain excellent emulsification and soluble protein content after heat treatment. Further analysis using Fourier transform infrared spectroscopy showed that the increase in α-helix content in liquid egg yolk treated with sugar salt also contributes to improving the thermal stability of egg yolk. The method of inhibiting egg yolk aggregation caused by heat treatment provided in this study provides a selective method and theoretical basis for the commercial production of heat-resistant liquid egg yolk.

Effect of ultrasound pretreatment on structural, physicochemical, rheological and gelation properties of transglutaminase cross-linked whey protein soluble aggregates

A solution (10%, w/v) of whey protein soluble aggregates (WPISA) was pretreated with high-intensity ultrasound (HUS, 20 kHz) for different durations (10-40 min) before incubation with transglutaminase (TGase) to investigate the effect of HUS on the structural, physicochemical, rheological, and gelation properties of TGase cross-linked WPISA. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that HUS increased the amounts of high-molecular-weight polymers/aggregates in WPISA after incubation with TGase. HUS significantly increased (P < 0.05) the degree of TGase-mediated cross-linking in WPISA, as demonstrated by a reduction in free amino group contents. HUS significantly increased (P < 0.05) the particle size, intrinsic fluorescence intensity, and surface hydrophobicity of TGase cross-linked WPISA, but had no significant impact (P > 0.05) on the zeta-potential or total free sulfhydryl group content of TGase cross-linked WPISA. The apparent viscosity and the consistency index of TGase cross-linked WPISA were significantly increased by HUS (P < 0.05), which indicated that HUS facilitated the formation of more high-molecular-weight polymers. HUS significantly increased (P < 0.05) the water holding capacity and gel strength of glucono-δ-lactone (GDL)-induced TGase cross-linked WPISA gels. The results indicated that HUS could be an efficient tool for modifying WPISA to improve its degree of TGase-mediated cross-linking, which would lead to improved rheological and gelation properties.

Modification of pulse proteins for improved functionality and flavor profile: A comprehensive review

Consumers' preference to have a healthy eating pattern has led to an increasing demand for more nutrient-dense and healthier plant-based foods. Pulse proteins are exceptional quality ingredients with potential nutritional benefits, and might act as health-promoting agents for addressing the new-generation foods. However, the utilization of pulse protein in foods has been hampered by its relatively poor functionality and unpleasant flavor. Protein structure modification has been proved to be a useful means to improve the functionality and flavor profile of pulse protein. This paper begins with a brief introduction of hierarchical structure of pulse protein materials to better understand the structure characteristics. A comprehensive review is presented on the current techniques including chemical and enzymatic modifications and molecular breeding on pulse protein structure and functionality/flavor. The mechanism and the limitations and the toxicological concerns of these approaches are discussed. We conclude that understanding protein structure-functionality relationship is extremely valuable in tailoring proteins for specific functional outcomes and expanding the availability of pulse proteins. Furthermore, selective protein modification is a valuable in-depth toolkit for generating novel protein constructs with preferable functional attributes and flavor profiles. Innovative structure modification with special focus on the molecular basis for the exquisite protein designs is a pillar of pulse protein access to the desired functionality.

Production of self-assembling acylated ovalbumin nanogels as stable delivery vehicles for curcumin

In this study, we evaluated potential usage of acylated ovalbumin (AOVA) nanogels fabricated via acylation modification and heat-induced self-assembly process as novel delivery systems for curcumin. Compared to native ovalbumin (NOVA) nanogels without chemical acylation, the obtained AOVA nanogels have shown smaller average hydrodynamic diameter (155.73 nm), relatively uniform size distribution (polydispersity index around 0.28), enhanced negative surface charge (-24.3 mV), and an improved stability under the conditions of high ionic strength, different pH and storage time. Moreover, AOVA nanogels exhibited a remarkable conformational change in secondary and tertiary structures, improved surface hydrophobicity, and increased free sulfhydryl content compared with NOVA nanogels. Moreover, curcumin encapsulated in AOVA nanogels displayed higher encapsulation efficiency (93.64%) and slower sustained release under simulated gastrointestinal conditions as compared with NOVA nanogels. Hence, we have suggested that AOVA nanogels successfully fabricated with improved physicochemical properties as a novel ideal carrier for hydrophobic active compounds.

Covalent β-lactoglobulin-maltodextrin amyloid fibril conjugate prepared by the Maillard reaction

The surface modification of β-lactoglobulin amyloid fibrils (AFs) was investigated by performing the Maillard reaction with the free anomeric carbon of the maltodextrin in water at pH 9.0 and 90 °C. The bonding of maltodextrin to fibrils was confirmed by determining the free amino group content and the presence of final products from the Maillard reaction. The secondary structure of AFs was preserved as observed by circular dichroism analysis. Atomic force microscopy evidenced that prolonged heat treatment caused hydrolysis of the attached polysaccharide and consequently lowered the height of the fibrils from 8.0 nm (after 1 h) to 6.0 nm (after 24 h), which led to the reduction of hydrophilicity of resulting conjugate. Increasing the reaction time, however, resulted in the improvement of colloidal stability and decrease in turbidity ascribed to the increment of glycation degree, as well as, a decrease in the isoelectric point of the protein-based supramolecular object.