Impact of the release rate of magnesium ions in multiple emulsions (water-in-oil-in-water) containing BSA on the resulting physical properties and microstructure of soy protein gel

Developing edible oleogels structure prepared with emulsion-template approach based on soluble biopolymer complex

The utilization of edible oleogels as oil structures has been proven to comprise a suitable alternative to fat. In this research, whey protein concentrate (WPC) oleogel structure was designed and improved by the creation of a soluble complex of WPC-basil seed gum (BSG) and WPC-xanthan gum (XG) at different concentrations (0.2, 0.4, and 0.6 % w/w). The results showed increasing the hydrocolloids had positive effects on oleogel characteristics, which can preserve oil well in the microstructure network of oleogel. Additionally, the incorporation of hydrocolloids promoted stability of oleogels against stress and heat. Therefore, the centrifuge stability of WPC oleogel was 26 and increase to ∼98 and 100 % in 0.6XG:WPC and 0.6BSG:WPC oleogels, respectively. The evaluation of the rheological properties revealed the predominant elastic behavior of the oleogles. Overall, the addition of either XG or BSG into WPC-based oleogel improved its physicochemical and mechanical characteristics. Moreover, oleogels prepared using 0.6 % BSG-5 % WPC exhibited the best properties.

Research Progress on Tofu Coagulants and Their Coagulation Mechanisms

Tofu has captivated researchers' attention due to its distinctive texture and enrichment in nutritional elements, predominantly soybean protein. Coagulants play a critical role in promoting coagulation during tofu production, directly influencing its texture, quality, and physicochemical characteristics. Currently, the impact of coagulant characteristics on coagulation, as well as the underlying mechanisms, remain unclear. This review provides a summary of research progress on salt coagulants, acid coagulants, enzyme coagulants, novel coagulants, polysaccharide additives, and various coagulant formulations. The coagulation mechanisms of various coagulants are also discussed. Accordingly, this paper seeks to offer reliable theoretical guidance for the development of novel coagulants and the realization of fully automated tofu production.

The Preparation of W/O/W High-Internal-Phase Emulsions as Coagulants for Tofu: The Effect of the Addition of Soy Protein Isolate in the Internal Water Phase

Tofu quality is determined by a controlled coagulation process using a W/O/W emulsion coagulant. The impact of adding soy protein isolate (SPI) to the inner water phase on the stability of W/O/W high-internal-phase emulsions (HIPEs) and its application as a coagulant for tofu was assessed. No creaming occurred during 7-day storage with SPI concentrations up to 0.3%, while the emulsion droplets aggregated with 0.5% and 0.7% SPI. Emulsions containing 0.3% SPI maintained a constant mean droplet size after 21 days of storage and exhibited the lowest TURBISCAN stability index value. HIPE stability against freeze-thaw cycles improved after heating. HIPEs with SPI concentrations above 0.3% demonstrated an elastic gel-like behavior. The increased viscosity and aggregation of the protein around droplets indicated that the interaction among emulsion droplets could enhance stability. W/O/W HIPE coagulants significantly increased tofu yield, reduced hardness, and produced a more homogenous tofu gel compared to a MgCl2 solution. The HIPE with 0.3% SPI was found to be optimal for use as a coagulant for tofu.

Polyglycerol polyricinoleate and lecithin stabilized water in oil nanoemulsions for sugaring Beijing roast duck: Preparation, stability mechanisms and color improvement

Traditional Beijing roast duck often suffers from uneven color and high sugar content after roasting. Water-in-oil (W/O) nanoemulsion is a promising alternative to replace high concentration of sugar solution used in sugaring process according to similarity-intermiscibility theory. Herein, 3% of xylose was embedded in the aqueous phase of W/O emulsion to replace 15% maltose solution. W/O emulsions with different ratios of lecithin (LEC) and polyglycerol polyricinoleate (PGPR) were constructed by high-speed homogenization and high-pressure homogenization. Distribution and penetration extent of solutions and emulsions through the duck skin, as well as the color uniformity of Beijing roast duck were analyzed. Emulsions with LEC:PGPR ratios of 1:3 and 2:2 had better stability. Stable interfacial film and spatial structure were important factors influencing emulsion stabilization. The stable W/O emulsions could more uniformly distribute onto the surface of duck skin and longitudinally penetrate through the skin than solutions.

Effect of Diacylglycerol Crystallization on W/O/W Emulsion Stability, Controlled Release Properties and In Vitro Digestibility

Water-in-oil-in-water (W/O/W) emulsions with high-melting diacylglycerol (DAG) crystals incorporated in the oil droplets were fabricated and the compositions were optimized to achieve the best physical stability. The stability against osmotic pressure, encapsulation efficiency and in vitro release profiles of both water- and oil-soluble bioactives were investigated. The presence of interfacial crystallized DAG shells increased the emulsion stability by reducing the swelling and shrinkage of emulsions against osmotic pressure and heating treatment. DAG crystals located at the inner water/oil (W1/O) interface and the gelation of the inner phase by gelatin helped reduce the oil droplet size and slow down the salt release rate. The DAG and gelatin-contained double emulsion showed improved encapsulation efficiency of bioactives, especially for the epigallocatechin gallate (EGCG) during storage. The double emulsions with DAG had a lower digestion rate but higher bioaccessibility of EGCG and curcumin after in vitro digestion. DAG-stabilized double emulsions with a gelled inner phase thus can be applied as controlled delivery systems for bioactives by forming robust interfacial crystalline shells.

Modulation of soy protein isolate gel properties by a novel "two-step" gelation process: Effects of pre-aggregation with different divalent sulfates

A novel pre-aggregation process prior to gelation was applied to modulate the aggregation and gelation pathway of soy protein isolate (SPI). SPI dispersions were pre-aggregated with CaSO₄, MgSO₄ or ZnSO₄ at 0-15 mM and then gelled by adding CaSO₄ up to a final salt concentration of 35 mM. Compared with the sample without pre-aggregation, the storage modulus of SPI gels pre-aggregated with 10 mM CaSO₄, 10 mM MgSO₄, and 2.5 mM ZnSO₄ were increased by 50.5%, 35.7%, and 63.6%, respectively. The fracture stress, texture profile analysis parameters, and water holding capacity were markedly improved by an appropriate level of pre-aggregation. To a certain extent, pre-aggregation could promote the formation of uniform structure with thicker strands, whereas over-aggregation resulted in a coarser network, which was correlated with the volume-mean diameter (D_4,3) of pre-aggregated SPI particles. The results are of great value for further understanding of gelation mechanism of proteins.

Recent advances on food-grade water-in-oil emulsions: Instability mechanism, fabrication, characterization, application, and research trends

Owing to their promising application prospects, water-in-oil (W/O) emulsions have aroused continuous attention in recent years. However, long-term stability of W/O emulsions remains a particularly challenging problem in colloid science. With the increasing demand of consumers for natural, green, and healthy foods, the heavy reliance on chemically synthesized surfactants to achieve long-term stability has become the key technical defect restricting the application of W/O emulsions in food. To design and manufacture W/O emulsions with long-term stability and clean label, a comprehensive understanding of the fundamentals of the W/O emulsion system is required. This review aims to demystify the field of W/O emulsions and update its current research progress. We first provide a summary on the essential basic knowledge regarding the instability mechanisms, including physical and chemical instability in W/O emulsions. Then, the formulation of the W/O emulsion system is introduced, particularly focusing on the use of natural stabilizers. Besides, the characterization and application of W/O emulsions are also discussed. Finally, we propose promising research trends, including (1) developing W/O high internal phase emulsions (HIPEs) as fat mimetic and substitute, (2) promising formulation routine for long-term stable double emulsions, and (3) searching for novel plant-derived stabilizers of W/O emulsions.

Improved physicochemical stability of emulsions enriched in lutein by a combination of chlorogenic acid-whey protein isolate-dextran and vitamin E

Lutein, as a bioactive substance, has the ability to decrease the risk of some chronic diseases, but the poor water solubility, chemical instability, and low bioaccessibility limit its wide application in foods. In this study, an emulsion-based delivery system stabilized by chlorogenic acid (CA)-whey protein isolate (WPI)-dextran (DEX) ternary conjugates was prepared and vitamin E (VE) was added to increase the chemical stability of lutein. Molecular weight and conformational information of ternary conjugates were obtained by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, fluorescence spectroscopy, and Fourier transform infrared spectroscopy. o-Phthalaldehyde results suggested that the extent of glycation was 16.4% and 19.5% for (CA-WPI)-DEX and WPI-DEX conjugates, respectively. The physicochemical stability of lutein-enriched emulsions was evaluated under different environmental stresses and long-term storage. The obtained results showed that compared with emulsions stabilized by WPI alone or binary conjugates, ternary conjugates imparted emulsions high stability under different environmental stress conditions (ionic strength, freeze-thaw, and heat) and long-term storage (within 3 weeks). VE can effectively decrease the degradation rate of lutein without changing the physical stability of emulsions. Additionally, the lutein-enriched emulsions prepared by ternary conjugates and VE exhibited a relatively high bioaccessibility. PRACTICAL APPLICATION: The ternary conjugates constructed in this paper has excellent physicochemical characteristics to stabilize emulsion, and can increase the water solubility of functional factors and reduce their degradation rate. Additionally, this conjugate was prepared by food-grade materials. Therefore, it can be used as emulsion-based delivery systems in food industrials.

Latest advances in imaging techniques for characterizing soft, multiphasic food materials

Over the last two decades, the development and production of innovative, customer-tailored food products with enhanced health benefits have seen major advances. However, the manufacture of edible materials with tuned physical and organoleptic properties requires a good knowledge of food microstructure and its relationship to the macroscopic properties of the final food product. Food products are complex materials, often consisting of multiple phases. Furthermore, each phase usually contains a variety of biological macromolecules, such as carbohydrates, proteins and lipids, as well as water droplets and gas bubbles. Micronutrients, such as vitamins and minerals, might also play an important role in determining and engineering food microstructure. Considering this complexity, highly advanced physio-chemical techniques are required for characterizing the microstructure of food systems prior to, during and after processing. Fast, in situ techniques are also essential for industrial applications. Due to the wide variety of instruments and methods, the scope of this paper is focused only on the latest advances of selected food characterization techniques, with emphasis on soft, multi-phasic food materials.

Evaluating the Stability of Double Emulsions—A Review of the Measurement Techniques for the Systematic Investigation of Instability Mechanisms

Double emulsions are very promising for various applications in pharmaceutics, cosmetics, and food. Despite lots of published research, only a few products have successfully been marketed due to immense stability problems. This review describes approaches on how to characterize the stability of double emulsions. The measurement methods are used to investigate the influence of the ingredients or the process on the stability, as well as of the environmental conditions during storage. The described techniques are applied either to double emulsions themselves or to model systems. The presented analysis methods are based on microscopy, rheology, light scattering, marker detection, and differential scanning calorimetry. Many methods for the characterization of double emulsions focus only on the release of the inner water phase or of a marker encapsulated therein. Analysis methods for a specific application rarely give information on the actual mechanism, leading to double emulsion breakage. In contrast, model systems such as simple emulsions, microfluidic emulsions, or single-drop experiments allow for a systematic investigation of diffusion and coalescence between the individual phases. They also give information on the order of magnitude in which they contribute to the failure of the overall system. This review gives an overview of various methods for the characterization of double emulsion stability, describing the underlying assumptions and the information gained. With this review, we intend to assist in the development of stable double emulsion-based products.

Water-in-oil-in-water double emulsions loaded with chlorogenic acid: release mechanisms and oxidative stability

Chlorogenic acid (CA) is a natural compound used as an antioxidant in the preparation of food, drugs, and cosmetics. Due to their low stability and bioavailability, many researchers have studied the encapsulation of CA in various delivery colloidal systems. The aim of this study was to evaluate the stability of water-in-oil-in-water (W/O/W) double emulsions loaded with CA and its antioxidant capacity. For this purpose, CA-W/O/W double emulsions were prepared using Span 80 and lecithin as lipophilic emulsifiers, and Tween 20 as a hydrophilic emulsifier. The influence of nature of lipophilic emulsifiers, the presence of chitosan (CH) in the internal and external aqueous phases, pH, temperature and the storage time of W/O/W double emulsions were also investigated. Depending on the preparation conditions, the W/O/W double emulsions showed the droplet size in the range 9.13 ± 0.55 μm-38.21 ± 1.87 μm, the creaming index 34%-78% and the efficiency encapsulation 79.45 ± 1.5%-88.13 ± 1.9%. Zeta potential values were negative for the W/O/W double emulsion without CH (-36.8 ± 2.02mV; -27.3 ± 1.75mV) and positive for the W/O/W double emulsions with CH in the external aqueous phase (+6.5 ± 0.42mV; 28.6 ± 0.92mV). The study of the release of CA from W/O/W double emulsions has highlighted two mechanisms: one based on the coalescence between the water inner droplets or between the oil globules as well as a diffusion releasing mechanism. The oxidative stability parameters of the W/O/W double emulsions, such as the peroxide value (POV) and the conjugated diene content (CD) were measured.

Preparation of α-Linolenic-Acid-Loaded Water-in-Oil-in-Water Microemulsion and Its Potential as a Fluorescent Delivery Carrier with a Free Label

Our previous work has demonstrated that α-linolenic acid (ALA)-loaded oil-in-water (O/W) microemulsion could enhance ALA antioxidant capacity. Meanwhile, we also observed that synthesized microemulsion itself had fluorescence. In this work, we have prepared a multiple water-in-oil-in-water (W/O/W) microemulsion to further enhance ALA antioxidant capacity and activate this delivery carrier application potential with a free label. The compositions of primary water-in-oil (W/O) microemulsion were obtained using pseudo-ternary phase diagrams, and then W/O/W microemulsion was prepared adopting the "two-step heterotherm method". The conductivity of W/O/W microemulsion was measured to lie between 250.0 and 350.0 μs/cm. The spherical droplets with a mean particle diameter of 10.0-20.0 nm were confirmed by transmission electron microscopy and dynamic light scattering. Nuclear magnetic resonance confirmed that ALA diffused to the multiple water-oily interface simultaneously. In addition, the in vitro release and antioxidant capacity measurements of ALA-loaded W/O/W microemulsion concluded the sustained-release effect and excellent antioxidant capacity. The fluorescent intensity of W/O/W microemulsion was markedly increased in comparison to O/W microemulsion. The synthesized microemulsion could lead to important applications and have advantages of a label-free fluorescent carrier for optical imaging purposes.

Curcumin nanocapsules stabilized by bovine serum albumin-capped gold nanoclusters (BSA-AuNCs) for drug delivery and theranosis

Nanotechnology plays an important role in the development of drug delivery, imaging, and diagnosis. In this study, nanocapsules containing protein-functionalized gold nanoclusters (AuNCs) as the shell and hydrophobic drug curcumin as the core were prepared as a tumor cell theranostic agent. After the nanocapsules were added into tumor cell media, they entered the cells with high efficiency and exhibited strong fluorescence within the cells. The results indicated that the nanocapsules were broken up in the cells and curcumin was released. Simultaneously, the nanocapsules exhibited significant inhibition effect against tumor cell proliferation in a concentration- and time-dependent manner, and the images of atomic force microscopy (AFM) showed that the cell morphology underwent obvious changes after the capsule treatment. Additionally, cell membrane appeared wrinkles after the cells treated with the nanocapsules, resulting in a rough cell surface, implying that the cytoskeleton would involve in the cell uptake of nanocapsules. Moreover, the AuNCs and curcumin in the system could exert synergistic effect on the inhibition of tumor cell growth and induction of cell apoptosis. The study highlights the potential of the system as a promising agent for drug delivery and tumor cell theranosis.