Study of the phase separation behaviour of native or preheated WPI with polysaccharides

Liquid-liquid biopolymers aqueous solution segregative phase separation in food: From fundamentals to applications-A review

As a result of the spontaneous movement of molecules, liquid-liquid biopolymer segregative phase separation takes place in an aqueous solution. The efficacy of this type of separation can be optimized under conditions where variables such as pH, temperature, and molecular concentrations have minimal impact on its dynamics. Recently, interest in the applications of biopolymers and their segregative phase separation-associated molecular stratification has increased, particularly in the food industry, where these methods permit the purification of specific particles and the embedding of microcapsules. The present review offers a comprehensive examination of the theoretical mechanisms that regulate the liquid-liquid biopolymers aqueous solution segregative phase separation, the factors that may exert an impact on this procedure, and the importance of this particular separation method in the context of food science. These discussion points also address existing difficulties and future possibilities related to the use of segregative phase separation in food applications. This highlights the potential for the design of novel functional foods and the enhancement of food properties.

Elucidation of interactions between myofibrillar proteins and κ-carrageenan as mediated by NaCl level: Perspectives on multiple spectroscopy and molecular docking

The present study was aimed to investigate the intermolecular interaction between myofibrillar proteins (MP) and κ-carrageenan (KC) as mediated by KC concentration (0.1, 0.2, 0.3, and 0.4 %, w/w) and NaCl levels (0.3 and 0.6 M) based on the multiple spectroscopy and molecular docking. The results showed that the incorporation of KC increased the turbidity, zeta-potential, and surface hydrophobicity of MP-KC mixed sols with a dose-dependent manner, as well as significantly decreasing the protein solubility (P < 0.05), which indicated that the interaction between KC and MP promoted the expansion of protein structure and exposed more hydrophobic groups. Fluorescence spectra result revealed that the interaction between MP and KC was a static quenching in the fluorescence quenching process, which affected the aromatic amino acids residue microenvironment of MP. Moreover, the existence of KC decreased the α-helix contents of MP (P < 0.05), contributing to the transformation from random structure to organized configuration of MP. In addition, molecular forces, the molecular docking and thermodynamic parameters indicated that hydrophobic interactions, van der Waals force, and hydrogen bonding were considered as the main interaction forces between MP and KC. Furthermore, 0.6 M NaCl level rendered higher solubility and particle size, as well as lower turbidity and the surface hydrophobicity of MP-KC mixed sols than those with 0.3 M NaCl level (P < 0.05), which promoted the unfolding of MP molecule and subsequently increased the numbers of binding sites between MP and KC, facilitating the intermolecular interactions between MP and KC in mixed sols.

A pH-indicating smart tag based on porous hydrogel as food freshness sensors

HYPOTHESIS

The pH-indicating smart packaging and tags are identified within the general research and pH colorimetric smart tags are effective, non-invasive methods for indicating food freshness on a real-time basis, but their sensitivity is limited.

EXPERIMENTS

In Herin, we developed a porous hydrogel with high sensitivity, water content, modulus, and safety. Hydrogels were prepared with gellan gum, starch, and anthocyanin. The phase separations provide an adjustable porous structure, which can enhance the capture and transformation of gas from food spoilage, hence improving the sensitivity. Hydrogel is physically crosslinked by the entanglement of chains through freeze-thawing cycles, and porosity can be adjusted by the addition of starch, so avoiding the use of toxicity crosslinkers and porogen.

FINDINGS

Our study demonstrates that the gel undergoes an obvious color shift during the spoilage of milk and shrimp, revealing its potential application as a smart tag signaling food freshness.

Segregative phase separation of gelatin and tragacanth gum solution and Mickering stabilization of their water-in-water emulsion with microgel particles prepared by complex coacervation

This study aimed to investigate the segregative interaction of gelatin (G) and tragacanth gum (TG) and the stabilization of their water-in-water (W/W) emulsion by G-TG complex coacervate particles. Segregation was studied at different pHs, ionic strengths and biopolymer concentrations. Results showed that incompatibility was affected by increasing the biopolymer concentrations. So, three reigns were demonstrated in the phase diagram of the salt-free samples. NaCl significantly changed the phase behavior via enhancement of self-association of polysaccharide and changing solvent quality due to the charge screening effect of ions. The W/W emulsion prepared from these two biopolymers and stabilized with G-TG complex particles was stable for at least one week. The microgel particles improved emulsion stability by adsorption to the interface and creating a physical barrier. A fibrous and network-like structure of the G-TG microgels was observed by scanning electron microscopy images suggesting the Mickering emulsion stabilization mechanism. It was confirmed that the bridging flocculation between the microgel polymers led to phase separation after the stability period. Biopolymer incompatibility investigation is a useful tool to obtain beneficial knowledge for preparation new food formulation, especially no contain oil emulsions for low- calorie diets.

Effects of acetylated cassava starch on the physical and rheological properties of multicomponent protein emulsions

The present study investigates the effect of different acetylated cassava starch (ACS) concentrations on the physical and rheological properties of multicomponent emulsion-based products at specific pH values. The emulsion-based products were made by mixing 2% (w/v) prepared lipid droplets that were stabilized by either native or heated whey proteins, 0.01% (w/v) flaxseed gum and 0-6.0% (w/v) ACS. The results indicated that particle size, apparent viscosity and rheological moduli of multicomponent emulsion-based products were significantly enhanced with increasing addition amounts of ACS (P < 0.05). Moreover, the microscopic morphology showed that the addition of ACS contributed to the formation of a more compact, uniform, and continuous comb-like network. However, higher ACS concentration was prone to induce visibly larger aggregations and coarser textures, lending to some negative impact on visual appearance and overall acceptability. Moreover, acidic conditions could obviously promote droplet aggregation via electrostatic interactions, whereas neutral conditions had no effect on droplet aggregation. Additionally, when compared with native whey proteins, lipid droplets stabilized by their heated protein forms induced significantly higher apparent viscosities and rheological moduli of multicomponent emulsion-based products (P < 0.05). Our results potentially provide some information for the creation of multicomponent emulsion-based products with various desirable quality attributes.

Complexation between whey protein and octenyl succinic anhydride (OSA)-modified starch: Formation and characteristics of soluble complexes

Mixed systems of protein and polysaccharide are widely used in the food industry. It is important for food manufacturers to understand their interactions. In this study, the formation of complexes between whey protein isolate (WPI) and octenyl succinic anhydride (OSA)-modified starch was investigated as a function of pH and protein: starch ratio. OSA-modified starch tended to interact with heated WPI (HWPI) rather than non-heated WPI (NWPI), and the optimum conditions for their complexation were a protein: starch ratio of 1:10 and pH 4.5, probably driven by both electrostatic and hydrophobic interactions. The effects of the degree of substitution (DS) and molecular weight (Mw) of OSA-modified starch on the properties of the complexes formed under the optimum conditions were investigated using absorbance measurements (at 515 nm). Soluble complexes (HWPI-OSA SC) between 0.5% (w/v) HWPI and 5% (w/v) OSA-modified starch with a Mw of 19.24 ± 0.07 × 10⁴ g/mol and a DS of 4.29 ± 0.11% could be formed at pH 4.5. The structure of HWPI-OSA SC was examined using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Characterization of the HWPI-OSA SC revealed that the intermolecular interactions between HWPI and OSA-modified starch led to their different characteristics from HWPI and OSA-modified starch alone.

Mechanisms of whey protein isolate interaction with basil seed gum: Influence of pH and protein-polysaccharide ratio

In the present work, we determined the structure-function relationships of basil seed gum (BSG) and whey protein isolate (WPI) mixtures at the start of soluble complex formation, maximum soluble complex formation and predominant thermodynamic incompatibility to understand BSG:WPI blends interaction behavior. Accordingly, turbidity and zeta potential were analyzed in the pH range of 2.0-7.0 and BSG:WPI ratios of 1:4, 1:6.6 and 1:9. Dynamic rheometry was used to evaluate samples at three different pHs. Additionally, dilute solution properties of BSG, WPI and their blends were studied at pH = 7.0. Independent of mixture ratio, all dispersions showed maximum interaction at pH = 5.0, the start of soluble complex formation around pH = 6.0 and thermodynamic incompatibility interaction behavior at pH = 7.0. Cole-Cole plots based on dynamic rheometry supported the Gibbs free energy change of mixtures based on intrinsic viscosity data. These results are important to create new structures from mixtures of proteins and polysaccharides.

Use of molecular interactions and mesoscopic scale transitions to modulate protein-polysaccharide structures

Mixed protein-polysaccharide structures have found widespread applications in various fields, such as in foods, pharmaceuticals or personal care products. A better understanding and a more precise control over the molecular interactions between the two types of macromolecules leading to an engineering of nanoscale and colloidal building blocks have fueled the design of novel structures with improved functional properties. However, these building blocks often do not constitute the final matrix. Rather, further process operations are used to transform the initially formed structural entities into bulk matrices. Systematic knowledge on the relation between molecular structure design and subsequent mesoscopic scale transitions induced by processing is scarce. This article aims at establishing a connection between these two approaches. Therefore, it reviews not only studies on the underlying molecular interaction phenomena leading to either a segregative or associative phase behavior and nanoscale or colloidal structures, but also looks at the less systematically studied approach of using macroscopic processing operations such as shearing, heating, crosslinking, and concentrating/drying to transform the initially generated structures into bulk matrices. Thereby, a more comprehensive look is taken at the relationship between different influencing factors, namely solvent conditions (i.e. pH, ionic strength), biopolymer characteristics (i.e. type, charge density, mixing ratio, biopolymer concentration), and processing parameters (i.e. temperature, mechanical stresses, pressure) to generate bulk protein-polysaccharide matrices with different morphological features. The need for a combinatorial approach is then demonstrated by reviewing in detail current mixed protein-polysaccharide applications that increasingly make use of this. In the process, open scientific questions that will need to be addressed in the future are highlighted.