Surface properties and adsorption of lactoferrin-xanthan complex in the oil-water interface

Effects of polysaccharides on the structure, functionality, emulsion stability and rheological properties of soybean meal hydrolysate-proanthocyanidin complexes

In this study, the structure, functionality, physicochemical property, emulsion storage stability, and rheological properties of soybean meal hydrolysate-proanthocyanidin (SMH-PC) conjugates in ternary complex with glucan, sodium alginate, or soybean polysaccharides were investigated. Following complexing, the proteins unfolded and their disordered structures positively promoted the emulsifying properties of ternary complexes. The SMH-PC-glucan complex showed the best antioxidant activity and the highest emulsifying activity index (94.11 m2·g-1) and stability index (378.09 min). Moreover, the SMH-PC-glucan complex emulsion exhibited the best emulsion stability, including the smallest particle size and good storage stability. These findings demonstrate the potential of using modified SMHs as emulsifiers to increase the value of soybean meal.

Effect of pH, protein/polysaccharide ratio and preparation method on the stability of lactoferrin-polysaccharide complexes

In this study, carrageenan (CG), xanthan gum (XG) and locust bean gum (LBG), which can be used in infant formulas in China national standards, were selected to prepare LF-polysaccharide complexes to improve the stability of lactoferrin. The results showed that LF interacted more strongly with polysaccharides and did not affect the LF structure to a large extent when the pH and protein/polysaccharide mass ratio were 7 and 10:1 for LF-CG, 8 and 5:1 for LF-XG, 7 and 15:1 for LF-LBG. The zeta potential and fluorescence intensity of the LF-polysaccharide complexes displayed a decreasing trend with the increase in pH. When pH < 6, LF-CG and LF-XG exhibited precipitation and increased UV absorbance. Complexation between LF and CG/XG mainly attributed to electrostatic interactions, while LF and LBG form complexes based on hydrogen bonding or hydrophobic interactions. This study could provide a reference for the practical application of LF in infant formula.

Thermal stability and in vitro biological fate of lactoferrin-polysaccharide complexes

Lactoferrin (LF) is a thermally sensitive iron-binding globular glycoprotein. Heat treatment can induce its denaturation and aggregation and thus affect its functional activity. In this study, carrageenan (CG), xanthan gum (XG) and locust bean gum (LBG), allowed to apply in infant food, were used to form protein-polysaccharide complexes to improve the thermal stability of LF. Meanwhile, in vitro simulated infant digestion and absorption properties of LF were also estimated. The results showed that the complexes formed by CG and XG with LF (LF-CG and LF-XG) could significantly inhibit the loss of α-helix structure of LF against heating. LF-CG and LF-LBG could protect LF from digestion in simulated infant gastric fluid and slow down the degradation of LF under the simulated intestinal conditions. Besides, LF, LF-CG and LF-XG showed no adverse effects on the growth of Caco-2 cells in the LF concentration range of 10-300 μg/mL, and LF-XG exhibited better beneficial to improve the cell uptake of the digestive product than the other protein-polysaccharides at the LF concentration of 100 µg/mL. This study may provide a reference for the enhancement of thermal processing stability of LF and development infant food ingredient with high nutrients absorption efficiency in the gastrointestinal environment in the future.

Protein-Stabilized Emulsion Gels with Improved Emulsifying and Gelling Properties for the Delivery of Bioactive Ingredients: A Review

In today's food industry, the potential of bioactive compounds in preventing many chronic diseases has garnered significant attention. Many delivery systems have been developed to encapsulate these unstable bioactive compounds. Emulsion gels, as colloidal soft-solid materials, with their unique three-dimensional network structure and strong mechanical properties, are believed to provide excellent protection for bioactive substances. In the context of constructing carriers for bioactive materials, proteins are frequently employed as emulsifiers or gelling agents in emulsions or protein gels. However, in emulsion gels, when protein is used as an emulsifier to stabilize the oil/water interface, the gelling properties of proteins can also have a great influence on the functionality of the emulsion gels. Therefore, this paper aims to focus on the role of proteins' emulsifying and gelling properties in emulsion gels, providing a comprehensive review of the formation and modification of protein-based emulsion gels to build high-quality emulsion gel systems, thereby improving the stability and bioavailability of embedded bioactive substances.

Sustaining Protein Nutrition Through Plant-Based Foods

Proteins are essential components of the human diet. Dietary proteins could be derived from animals and plants. Animal protein, although higher in demand, is generally considered less environmentally sustainable. Therefore, a gradual transition from animal- to plant-based protein food may be desirable to maintain environmental stability, ethical reasons, food affordability, greater food safety, fulfilling higher consumer demand, and combating of protein-energy malnutrition. Due to these reasons, plant-based proteins are steadily gaining popularity, and this upward trend is expected to continue for the next few decades. Plant proteins are a good source of many essential amino acids, vital macronutrients, and are sufficient to achieve complete protein nutrition. The main goal of this review is to provide an overview of plant-based protein that helps sustain a better life for humans and the nutritional quality of plant proteins. Therefore, the present review comprehensively explores the nutritional quality of the plant proteins, their cost-effective extraction and processing technologies, impacts on nutrition, different food wastes as an alternative source of plant protein, and their environmental impact. Furthermore, it focuses on the emerging technologies for improving plant proteins' bioavailability, digestibility, and organoleptic properties, and highlights the aforementioned technological challenges for future research work.

Soy/whey protein isolates: interfacial properties and effects on the stability of oil-in-water emulsions

BACKGROUND

The adsorption of proteins at oil/water interfaces can reduce interfacial tension and increase emulsion stability. However, emulsions stabilized by soy protein isolate (SPI) are not sufficiently stable. Using SPI as a control, a theoretical basis for the adsorption behavior of mixed SPI and whey protein isolate (WPI) at the oil/water interface was established and the effects of the protein ratio and content on the emulsion stability were studied.

RESULTS

Compared to SPI solution, SPI-WPI mixed solutions were found to reduce the size distribution of emulsion droplets and significantly improve the emulsion stability. Among the studied protein contents and ratios, the protein content of 0.2 g kg^-1 and SPI/WPI mass ratio of 1:9 offered the lowest creaming stability index (15%), the smallest droplet size (278 nm), and the largest absolute value ζ-potential (35 mV), i.e. the emulsion stability was excellent. The largest dilatational modulus (10.08 mN m^-1 ), dilatational elasticity (10.01 mN m^-1 ), and dilatational viscosity (1.18 mN m^-1 ), were observed with a protein content of 0.15 g kg^-1 (SPI/WPI ratio of 1:9), along with a high interfacial protein adsorption capacity (47.33%). SPI-WPI complexes form a thick adsorption layer around oil droplets, resulting in an increase of the expansion modulus of the interfacial layer.

CONCLUSION

SPI-WPI complexes can form a thick adsorption layer around oil droplets, resulting in increased expansion modulus of the interfacial layer, which improves emulsion stability. © 2020 Society of Chemical Industry.