Whey Protein Isolate Concentration Research Articles

Improving salidroside stability using water-in-oil-in-water emulsion with whey protein isolate: Formation and characterization

A water-in-oil-in-water (W/O/W) emulsion for the encapsulation of salidroside (Sal) was constructed. This study aimed to detect the impact of whey protein isolate (WPI) on the microstructure and stability of Sal W/O/W emulsion, which was prepared by two-step emulsification. First, Sal and sodium alginate (SA) were added to the inner water phase, and polyglycerol polyricinoleate (PGPR) was added to the oil phase to prepare a water-in-oil (W/O) emulsion. Second, different concentrations of WPI were added to the outer water phase containing SA to prepare a Sal W/O/W emulsion. The microstructure, stability, moisture distribution, rheological properties, and encapsulation efficiency of Sal were detected. The results showed that the particle size and the size distribution range became smaller and narrower with increasing WPI concentration. When the concentration of WPI was greater than 2%, the double-layer structure remained stable over 28 days of storage at 4 °C. Moreover, when the WPI concentration reached 4%, the entrapment efficiency of Sal was the highest. These results indicated that the optimum concentration of WPI was 4%.

Grafted calcium pectinate-whey protein isolate covalent immobilizers: Optimization, kinetics, thermodynamics, and application

Whey protein isolate (WPI) was incorporated within calcium pectinate (CPT) beads in order to boost their anionic qualities and meliorate their glutaraldehyde (GA)-polyethyleneimine (PEI) grafting process. The Box-Behnken Design (BBD) verified that WPI inclusion significantly raised the GA-PEI-CPT-WPI beads immobilized β-D-galactosidase (iβ-GLD) activity. The BBD also revealed the optimal settings for WPI concentration, PEI pH, PEI concentration, and GA concentration, which were 2.91 %, 10.8, 3.5 %, and 2.24 %, respectively. The GA-PEI-CPT-WPI beads grafting process was scrutinized via FTIR, EDX, and SEM. The optimal GA-PEI-CPT-WPI immobilizers provided fine β-GLD immobilization efficiencies, which reached up to 65.28 %. The free and GA-PEI-CPT-WPI iβ-GLDs pH and temperature profiles were scrutinized. It was also unveiled that the thermal stability of the iβ-GLD surpassed that of its free compeer as it provided lesser kd and ΔS values and larger t1/2, D-values, Ed, ΔH, and ΔG values. Furthermore, the iβ-GLD provided 92.00±3.39 % activity after 42 storage days, which denoted its fine storage stability. The iβ-GLD short duration (15 min) operational stability was also inspected, and 82.70±0.78 % activity was provided during the fifteenth degradation run. Moreover, the iβ-GLD long duration (24 h) operational stability was inspected while degrading the lactose of buffered lactose solution (BLS) and cheese whey (CW). It was unveiled that 81.86±0.96 % and 73.58±2.24 % of the initial glucose were detected during the sixth degradation runs, respectively.

Whey protein isolate-stabilized gardenia fruit oil nanoemulsions: Ultrasonic preparation, characterization and applications in nutraceuticals delivery

In the current research, ultrasound was applied to make whey protein isolate (WPI)-gardenia fruit oil nanoemulsion. Effects of preparation conditions on physicochemical characteristics of nanoemulsions were investigated. The smallest droplet size was obtained at the oil content of 10% (v/v) and the WPI concentration of 0.5% (w/v) with ultrasound (2.4 W/mL, 12 min). Ultrasound led to a more uniform nanoemulsion with smaller droplet sizes (< 300 nm). The nanoemulsion prepared with ultrasound remained relatively stable for more than one week, while the crude emulsion prepared without ultrasound layered after 1 day storage. The nanoemulsion was more stable at lower temperature, alkaline condition and lower Na+ concentration. The formation of nanoemulsions significantly reduced the generation rate and amount of POV and TBARS during the 14-day accelerated oxidation experiment, increasing the oxidation stability of gardenia fruit oil. Additionally, the nanoemulsion could encapsulate β-carotene, hesperetin and naringenin at the efficiency of 79.61%, 51.29% and 46.06%, which further improved the oil oxidation stability and retarded free fatty acids release during the stimulated digestion in vitro.

Combination of Machine Learning and Raman Spectroscopy for Determination of the Complex of Whey Protein Isolate with Hyaluronic Acid.

Macromolecules and their complexes remain interesting topics in various fields, such as targeted drug delivery and tissue regeneration. The complex chemical structure of such substances can be studied with a combination of Raman spectroscopy and machine learning. The complex of whey protein isolate (WPI) and hyaluronic acid (HA) is beneficial in terms of drug delivery. It provides HA properties with the stability obtained from WPI. However, differences between WPI-HA and WPI solutions can be difficult to detect by Raman spectroscopy. Especially when the low HA (0.1, 0.25, 0.5% w/v) and the constant WPI (5% w/v) concentrations are used. Before applying the machine learning techniques, all the collected data were divided into training and test sets in a ratio of 3:1. The performances of two ensemble methods, random forest (RF) and gradient boosting (GB), were evaluated on the Raman data, depending on the type of problem (regression or classification). The impact of noise reduction using principal component analysis (PCA) on the performance of the two machine learning methods was assessed. This procedure allowed us to reduce the number of features while retaining 95% of the explained variance in the data. Another application of these machine learning methods was to identify the WPI Raman bands that changed the most with the addition of HA. Both the RF and GB could provide feature importance data that could be plotted in conjunction with the actual Raman spectra of the samples. The results show that the addition of HA to WPI led to changes mainly around 1003 cm-1 (correspond to ring breath of phenylalanine) and 1400 cm-1, as demonstrated by the regression and classification models. For selected Raman bands, where the feature importance was greater than 1%, a direct evaluation of the effect of the amount of HA on the Raman intensities was performed but was found not to be informative. Thus, applying the RF or GB estimators to the Raman data with feature importance evaluation could detect and highlight small differences in the spectra of substances that arose from changes in the chemical structure; using PCA to filter out noise in the Raman data could improve the performance of both the RF and GB. The demonstrated results will make it possible to analyze changes in chemical bonds during various processes, for example, conjugation, to study complex mixtures of substances, even with small additions of the components of interest.

Improvement of phycocyanin stability at different temperatures using microencapsulation by whey protein isolate

Phycocyanin is a blue pigment in cyanobacteria known for its antioxidant activity and can be applied as a natural food colorant. However, one drawback to applying phycocyanin in food products is their high-temperature instability. In this research, we investigated the effect of encapsulation of phycocyanin using whey protein isolate (WPI) as the wall material to improve high-temperature stability. The study also assessed the physiochemical properties of microencapsulated phycocyanin. Phycocyanin was extracted from dry biomass Spirulina using a cold maceration method. Then, phycocyanin extract was encapsulated with prepared emulsions containing 0.25%, 0.50%, 0.75%, and 1.00% WPI as wall materials. The result showed all microencapsulated phycocyanin, regarding various concentrations of WPI, showed lower phycocyanin degradation at 60°C and 70°C at various heating times compared to control, suggesting higher stability. The control sample had 35.55±0.33% and 62.61±0.55% concentration degradation at 60°C and 70°C after 10 min heating. The microencapsulated phycocyanin with 0.50% WPI had 12.67±2.08% and 19.95±2.02% at 60°C and 70°C after 10 min heating. The encapsulation efficiency achieved 98-99% regarding various concentrations of WPI. There was no significant difference in solubility between the control and microencapsulated phycocyanin. Our result concluded that microencapsulation, using WPI as wall material, improved the high-temperature stability of phycocyanin.

WPI-coated liposomes as a delivery vehicle for enhancing the thermal stability and antioxidant activity of luteolin

The practical application of luteolin in food systems faces challenges due to its inherent instability. This study aimed to develop luteolin-loaded liposomes coated with whey protein isolate (WPI) to enhance the thermal stability and antioxidant activity of luteolin. The physical characteristics of both luteolin-loaded liposomes (LUT-Lips) and WPI-coated luteolin-loaded liposomes (WPI-LUT-Lips) were assessed. At a 5% WPI concentration, WPI-LUT-Lips demonstrated excellent dispersibility and improved encapsulation efficiency. WPI interacted with the liposome membrane via hydrophobic forces, hydrogen bonding, and electrostatic contact force, resulting in an efficient coating. Differential scanning calorimetry confirmed that WPI-LUT-Lips exhibited greater thermal stability compared to LUT-Lips, attributed to the protective effect of the WPI. Furthermore, WPI-LUT-Lips displayed superior antioxidant activity, as evidenced by their DPPH scavenging activity (86.36 ± 1.95%), TBARS reduction (25.33 ± 1.90%), and reducing power (82.86 ± 1.42%). Therefore, WPI-coated luteolin-loaded liposomes offer a promising way to enhance luteolin’s integration into food systems.

Endothelialization of Whey Protein Isolate-Based Scaffolds for Tissue Regeneration.

Whey protein isolate (WPI) is a by-product from the dairy industry, whose main component is β-lactoglobulin. Upon heating, WPI forms a hydrogel which can both support controlled drug delivery and enhance the proliferation and osteogenic differentiation of bone-forming cells. This study makes a novel contribution by evaluating the ability of WPI hydrogels to support the growth of endothelial cells, which are essential for vascularization, which in turn is a pre-requisite for bone regeneration. In this study, the proliferation and antioxidant levels in human umbilical vascular endothelial cells (HUVECs) cultured with WPI supplementation were evaluated using real-time cell analysis and flow cytometry. Further, the attachment and growth of HUVECs seeded on WPI-based hydrogels with different concentrations of WPI (15%, 20%, 30%, 40%) were investigated. Supplementation with WPI did not affect the viability or proliferation of HUVECs monitored with real-time cell analysis. At the highest used concentration of WPI (500 µg/mL), a slight induction of ROS production in HUVECs was detected as compared with control samples, but it was not accompanied by alterations in cellular thiol levels. Regarding WPI-based hydrogels, HUVEC adhered and spread on all samples, showing good metabolic activity. Notably, cell number was highest on samples containing 20% and 30% WPI. The demonstration of the good compatibility of WPI hydrogels with endothelial cells in these experiments is an important step towards promoting the vascularization of hydrogels upon implantation in vivo, which is expected to improve implant outcomes in the future.

Preparation and structural characterization of pullulan and whey protein isolate-based electrospun nanofiber

The impact of blended ratios was analyzed on the development and characterization of electrospun fibers using various combinations of pullulan (PUL) and whey protein isolate (WPI). The physical parameters like apparent viscosity, electrical conductivity and surface tension of blended solutions were improved after the addition of PUL in the blends, resulting in a uniform electrospun nanofiber. Scanning electron microscope (SEM) of nanofibers revealed bead-free, smooth and uniform structural conformation. Whereas, the uniformity of nanofiber was compromised by using higher concentrations of WPI in the blend. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and Thermogravimetry analysis further confirmed the strong molecular interaction between polysaccharide and protein. The incorporation of WPI in PUL based electrospun nanofibers enhanced hydrophobicity, potentially facilitating the delivery of bioactive compounds. The WPI and PUL:WPI-based nanofibers demonstrated robust antioxidant potential, due to the presence of total phenolic contents (TPC). The stability of PUL interaction with WPI (β-lactoglobulin and α-lactalbumin) was confirmed through hydro-carbon (C–H) and hydrogen bond interactions by molecular docking. Finally, we can conclude that polysaccharide and protein-based nanofiber can be used to deliver bioactive compounds in food and pharmaceutical industries.

Lesser mealworm (A. diaperinus) protein as a replacement for dairy proteins in the production of O/W emulsions: Droplet coalescence studies using microfluidics under controlled conditions

Dairy proteins are commonly used to stabilize oil-in-water (O/W) emulsions, which can be replaced by other sustainable sources of proteins, such as insects. This study investigated the potential of lesser mealworm protein concentrate (LMPC) as a sustainable alternative to whey protein isolate (WPI) in stabilizing oil-in-water (O/W) emulsions using microfluidics. The frequency of coalescence (Fcoal) was calculated using images of emulsion droplets obtained near the inlet and outlet of the coalescence channel. The stability of O/W emulsions, produced using sunflower oil (SFO) or hexadecane and stabilized with varying concentrations of LMPC and WPI (0.02% to 0.0005% w/v), was compared under controlled conditions. The dispersed phase fraction (5.3%-14.3% v/v), protein adsorption time onto oil droplets (0.0398–0.158 s), and pH (pH = 3 and pH = 7) were also studied. Fcoal was greatest (0.42 s−1) when the protein concentration was lowest (0.0005%), the oil percentage was highest (14.3%), the adsorption period was shortest (0.0398 s), and the pH was 3. Droplet diameters did not vary significantly, with values between 55 and 118 μm, across protein concentrations or adsorption periods, but a rise in oil fraction resulted in a substantial increase in droplet diameters. Increases in protein content, adsorption duration, and oil percentage all resulted in increased stability (reduction of Fcoal). While LMPC and WPI showed similar results in microfluidic experiments and other test conditions, further research is needed to verify LMPC's efficacy as a replacement for WPI in food emulsification. Nonetheless, the findings suggest that LMPC has potential as a substitute for WPI in this application.

Studying structural and rheological properties of alginate-whey protein isolate cold-set hybrid emulgels at various pH levels.

Effects of different pH values (4-7) and whey protein isolate (WPI) concentrations (0.5-1.5%) were evaluated on physical, mechanical, and rheological properties of cold-set alginate-based soybean oil hybrid emulgels. The pH value changes were more effective than WPI concentration changes on emulgel properties. According to syneresis and texture profile analysis results, 1% WPI was selected as the optimum concentration. The XRD analysis showed that calcium alginate (CA) emulgel at pH 6 had a different peak at 2θ of 14.8°, likely indicating the highest amount of ion-bridging and maximum number of junction zones. The homogeneity of CA and CA + WPI emulgels (determined by image entropy analysis) decreased by pH reduction from 7 to 4, which can be related to acid-induced intermolecular interactions between alginate chains. The rheological properties of CA and CA + WPI emulgels revealed predominant elastic character (G' > G'') at different pH values. Creep test results showed that the relative recovery of emulgel prepared at pH 7 and 5 was 18.10 and 63.83%, respectively, suggesting pH reduction contributed to increase in the elastic component of material. The findings of this study can be applied for developing structured cold-set emulgels as solid fat replacers in meat and dairy products.

Proliferation kinetics and mineralization properties of MC3T3‐E1 cells on whey protein isolate scaffolds for bone tissue regeneration

AbstractThe purpose of the study is to assess the influence of scaffold composition and properties on the cellular proliferation and scaffold mineralization on a whey protein isolate (WPI) scaffold. Scaffolds of varying concentrations of WPI, calcium chloride, and amylopectin are seeded with cells, and growth curves are constructed from cell density measurements following incubation. Non‐linear regression yields kinetic growth parameters which are compared for quantitative assessment of scaffold performance. Scaffolds show biocompatibility and the ability to sustain a culture for the length of the study. For up to 14 days, the data are well described by exponential growth. Thereafter, saturation behavior appears, and the data fit well to a sigmoidal model. The seeding efficiency improves with increasing WPI concentration, peaking at 5 mM CaCl2, and decreases with added amylopectin. The growth constant is almost independent of scaffold composition, with possible increases with added CaCl2 and amylopectin. The retardation constant is independent of composition. Scaffolds cultured in differentiation and mineralization conditions, shows development of a mineralized matrix both on acellular scaffold surfaces and in osteoblast cultures. The ability of the unmodified WPI gel surfaces to promote the growth and differentiation of a model preosteoblast provides valuable trends and concentration effects for further scaffold design.

Evaluation of ionic calcium and protein concentration on heat- and cold-induced gelation of whey protein isolate gels as a potential food formulation for 3D food printing

3D food printing (3DFP) is an innovative food process, but developing foods with ideal printability can prove challenging. Whey protein isolate (WPI) gels can be difficult to print due to their rigidity. This study evaluated the cold- and heat-induced gelation properties of WPI for use in 3DFP. Initially, the effect of WPI concentration ([WPI]) (8–12% (w/w)) and ionic calcium concentration ([Ca2+]) (0–8 mM) was evaluated on the heat-induced gelation capability and thermal reversibility. Treatments were categorised into three groups: thermo-irreversible, thermo-reversible, and non-gelling. Non-gelling treatments were used for cold-induced gelation by mixing the denatured WPI solution with 150 mM Ca2+ solution. Thermo-reversibility and cold-induced gelation properties were assessed using oscillatory rheometry. Finally, thermo-irreversible gels (TIRG) were characterised using extrudability and texture profile analysis. The thermo-reversible gels had an unsuitable range of G' (5–60 Pa) and δ (40–60°) for obtaining a self-standing object. Cold gelation using [WPI] = 10%, G' > 500 Pa and δ < 10°, may be suitable for 3DFP but requires an adapted extrusion-based 3D printer, i.e., co-extrusion, cooling or support bath. The extrusion force of TIRG decreased during heating and was mainly affected by [WPI]. Upon re-cooling, the force recovered (>85%) with the addition of [Ca2+] > 4 mM. TIRG using the following treatments [WPI]-[Ca2+] = 12% - 2 mM, 11% - 4 mM, and 10% - 6 mM demonstrated good printability. Principal component analysis showed TIRG with low hardness, resilience, and extrusion force loss during heating are potentially suitable for 3DFP.

Microencapsulation of marjoram essential oil as a food additive using sodium alginate and whey protein isolate

Encapsulation techniques are generally used to preserve the volatile compounds of essential oils. This study aimed to evaluate the influence of process variables on the microencapsulation of marjoram essential oil (MEO) (Origanum majorana L.) by ionic gelation. The effect of sodium alginate concentration (0.5–2 g/100 mL), emulsifier concentration (0.5–2 g/100 mL whey protein isolate (WPI)), and cationic bath concentration (0.05–0.3 mol/L CaCl2) on the emulsions and beads properties were investigated, according to a rotatable central composite design. MEO chemical composition and antimicrobial activity were assessed. Emulsions were characterized for droplet size and viscosity, while the particles were analyzed for encapsulation efficiency, size and circularity, and morphology. High concentrations of alginate and WPI intensified the porous structure of the beads, reducing droplet mean diameter and encapsulation efficiency. High alginate concentrations also increased emulsion viscosity, affecting positively beads' circularity. The intermediate concentration of sodium alginate (1.25 g/100 mL), WPI (1.25 g/100 mL), and CaCl2 (0.175 mol/L) were selected as the most appropriate conditions to produce beads with satisfactory circularity and high encapsulation efficiency.

Application of LF-NMR to characterize the roles of different emulsifiers in 3D printed emulsions

This study established a 3D printed food emulsions stabilized by whey protein isolate (WPI), hydroxypropylated starch (HS) and carrageenan. Low field nuclear magnetic resonance (LF-NMR) was applied to reveal role of WPI, HS and carrageenan on the mobility of hydrogen protons in these emulsions. T 2 distribution of 2% WPI and HS suspensions showed different hydrogen populations. And a new peak T 21 representing single layer water protons appeared at higher concentration. While T 21 was not found in all carrageenan dispersions. Rising of WPI, HS and carrageenan concentration all led to decline in T cur and T 2W values. For emulsions, increasing WPI concentration from 2% to 6% led to decrease in T 2W and T cur . Decreasing WPI/HS ratio prolonged the decay process as both T 2W and T cur values grew. Four proton signals showed in T 2 profile of most emulsions. The T 25 free water signal was closely correlated with WPI, HS, and carrageenan concentration. Decrease in T 24 peak time were observed when increasing WPI content. Influence of carrageenan on proton mobility of the emulsions were complicated and concentration-dependent, affecting relaxation peak T 21 , T 22 , T 24 , and T 25 . Apparent viscosity and rheological parameters G’ and G” indicated the emulsions exhibiting shear-thinning behavior with gel-like structure. Microstructure study revealed that addition of HS and carrageenan resulted in decline in emulsion droplet size. The printability of these WPI-stabilized emulsions was greatly affected by carrageenan content. Overall, this study proved the feasibility of using LF-NMR as a fast and effective approach for characterizing the effect of different emulsifiers in 3D printed emulsions when various types of emulsifiers existed. • LF-NMR can be used to rapidly characterize the roles of different emulsifiers in emulsions. • Relaxation behavior of emulsions were influenced by the type and concentration of emulsifiers used. • Microstructure, rheological properties, and 3D printability of emulsions were evaluated.

Could Curdlan/Whey Protein Isolate/Hydroxyapatite Biomaterials Be Considered as Promising Bone Scaffolds?-Fabrication, Characterization, and Evaluation of Cytocompatibility towards Osteoblast Cells In Vitro.

The number of bone fractures and cracks requiring surgical interventions increases every year; hence, there is a huge need to develop new potential bone scaffolds for bone regeneration. The goal of this study was to gain knowledge about the basic properties of novel curdlan/whey protein isolate/hydroxyapatite biomaterials in the context of their use in bone tissue engineering. The purpose of this research was also to determine whether the concentration of whey protein isolate in scaffolds has an influence on their properties. Thus, two biomaterials differing in the concentration of whey protein isolate (i.e., 25 wt.% and 35 wt.%; hereafter called Cur_WPI25_HAp and Cur_WPI35_HAp, respectively) were fabricated and subjected to evaluation of porosity, mechanical properties, swelling ability, protein release capacity, enzymatic biodegradability, bioactivity, and cytocompatibility towards osteoblasts in vitro. It was found that both biomaterials fulfilled a number of requirements for bone scaffolds, as they demonstrated limited swelling and the ability to undergo controllable enzymatic biodegradation, to form apatite layers on their surfaces and to support the viability, growth, proliferation, and differentiation of osteoblasts. On the other hand, the biomaterials were characterized by low open porosity, which may hinder the penetration of cells though their structure. Moreover, they had low mechanical properties compared to natural bone, which limits their use to filling of bone defects in non-load bearing implantation areas, e.g., in the craniofacial area, but then they will be additionally supported by application of mechanically strong materials such as titanium plates. Thus, this preliminary in vitro research indicates that biomaterials composed of curdlan, whey protein isolate, and hydroxyapatite seem promising for bone tissue engineering applications, but their porosity and mechanical properties should be improved. This will be the subject of our further work.

The impact of ethnicity and intra-pancreatic fat on the postprandial metabolome response to whey protein in overweight Asian Chinese and European Caucasian women with prediabetes.

The "Thin on the Outside Fat on the Inside" TOFI_Asia study found Asian Chinese to be more susceptible to Type 2 Diabetes (T2D) compared to European Caucasians matched for gender and body mass index (BMI). This was influenced by degree of visceral adipose deposition and ectopic fat accumulation in key organs, including liver and pancreas, leading to altered fasting plasma glucose, insulin resistance, and differences in plasma lipid and metabolite profiles. It remains unclear how intra-pancreatic fat deposition (IPFD) impacts TOFI phenotype-related T2D risk factors associated with Asian Chinese. Cow's milk whey protein isolate (WPI) is an insulin secretagogue which can suppress hyperglycemia in prediabetes. In this dietary intervention, we used untargeted metabolomics to characterize the postprandial WPI response in 24 overweight women with prediabetes. Participants were classified by ethnicity (Asian Chinese, n=12; European Caucasian, n=12) and IPFD (low IPFD < 4.66%, n=10; high IPFD ≥ 4.66%, n=10). Using a cross-over design participants were randomized to consume three WPI beverages on separate occasions; 0g (water control), 12.5g (low protein, LP) and 50g (high protein, HP), consumed when fasted. An exclusion pipeline for isolating metabolites with temporal (T0-240mins) WPI responses was implemented, and a support vector machine-recursive feature elimination (SVM-RFE) algorithm was used to model relevant metabolites by ethnicity and IPFD classes. Metabolic network analysis identified glycine as a central hub in both ethnicity and IPFD WPI response networks. A depletion of glycine relative to WPI concentration was detected in Chinese and high IPFD participants independent of BMI. Urea cycle metabolites were highly represented among the ethnicity WPI metabolome model, implicating a dysregulation in ammonia and nitrogen metabolism among Chinese participants. Uric acid and purine synthesis pathways were enriched within the high IPFD cohort's WPI metabolome response, implicating adipogenesis and insulin resistance pathways. In conclusion, the discrimination of ethnicity from WPI metabolome profiles was a stronger prediction model than IPFD in overweight women with prediabetes. Each models' discriminatory metabolites enriched different metabolic pathways that help to further characterize prediabetes in Asian Chinese women and women with increased IPFD, independently.

Changes in lipid compositions of krill oil emulsions during storage, a role of ultrasound treatment and the possible process of lipid migration

SummaryThe changes in lipid compositions of krill oil emulsions during storage were investigated, as well as the role of ultrasound treatment. Whey protein isolate (WPI) was used as wall materials to krill oil, which was treated with ultrasound. The effects of WPI concentration (from 0.2% to 10%), ultrasound power (from 10% to 80%) and treatment (at the same energy density with different power) were evaluated. Storage stability of different emulsions was characterised appearance, particle sizes, zeta potential, polydispersity index and microstructures. The lipid compositions and interactions were analysed to debate the changes of emulsions. The results indicated that ultrasound increased the stability of emulsions, enhanced the hydrophobic interactions between WPI and lipids and kept lipid composition distributions in each layer of emulsions. Furthermore, a possible mechanism of lipid migration in krill oil emulsions was put forward. The study will assist in the application and mechanism of krill oil emulsions treated with ultrasound.

The lipid digestion behavior of oil-in-water Pickering emulsions stabilized by whey protein microgels of various rigidities

Pickering emulsion stabilized by whey protein microgels (WPMs) possesses a retarded lipid digestion property may reduce the calorie intake. However, the rigidity of WPMs on emulsion stability and lipid digestion has not been investigated systematically. Herein, the WPMs with various rigidities made of 5%, 10% and 20% (w/w) whey protein isolate (WPI) were prepared. Atomic Force Microscopy characterization suggested that higher WPI concentration led to a larger young's modulus of microgel particles. The interfacial properties of the particles absorbed at the water-oil interface revealed that the soft microgel particles (5%) showed excellent deformability compared with the harder ones (10% and 20%). Besides, softer particles also exhibited faster interfacial adsorption rates, higher interfacial coverage and superior ability in reducing interfacial tension. Then those WPMs were applied to prepare oil-in-water Pickering emulsions. The soft WPMs stabilized Pickering emulsion showed the optimum colloidal stability. Furthermore, WPMs stabilized Pickering emulsions showed a delayed lipid digestion rate, thus the soft WPMs stabilized high internal phase Pickering emulsion was applied as a healthier margarine substitute. This work provides an inspiration for WPMs Pickering emulsions in reduced calorie intake food design. • Whey protein microgels with various rigidities were prepared by heat cross-linking. • Soft WPMs had excellent interfacial viscoelastic and absorption properties. • Soft WPMs-PE had the optimum colloidal stability. • WPMs-PEs built interfacial barriers and delayed lipid digestion rate effectively. • WPMs-HIPPE can be the potential healthier substitute to margarine.

Development and physicochemical properties of reformulated, high-protein, untempered sugar-free dark chocolates with addition of whey protein isolate and erythritol

The aim of this study was to determine the effect of whey protein isolate (WPI) and erythritol on physicochemical properties of untempered high-protein (16%, 20% and 24% of protein), sugar-free dark chocolates intended for athletes and diabetics. Surface properties were determined from contact angles, roughness and colour analysis. Melting characteristics were evaluated by Turbiscan. Water activity and viscosity were also tested. Higher WPI concentrations produced more hydrophobic surfaces of the samples and slightly increased their surface roughness. Increased whey protein addition improved shelf life, mechanical properties of chocolates and their resistance to melting; however, it had a minor effect on colour coordinates. Confocal microscopy proved the differences in the microstructure, samples with the highest WPI addition demonstrated more packed and denser structure. Application of WPI and erythritol induced an anti-blooming effect, which enabled skipping of tempering operation, and thus contributing to lower chocolate production costs and their improved nutritional profile.

Fabrication and Characterization of Ultra-High-Pressure (UHP)-Induced Whey Protein Isolate/κ-Carrageenan Composite Emulsion Gels for the Delivery of Curcumin.

The emulsion gels have attracted extensive interests due to their unique physical characters, remarkable stability, and control release properties of flavor and functional components compared to emulsions in liquid. In the current work, whey protein isolate (WPI)/κ-carrageenan (κ-CG) composite emulsion gels were fabricated based on the ultra-high-pressure (UHP) technology, in replacement of the traditional thermal, acid, or enzyme processing. Uniform composite emulsion gels could be fabricated by UHP above 400 MPa with minimum WPI and κ-CG concentrations of 8.0 and 1.0 wt%, respectively. The formation of UHP-induced emulsion gels is mostly attributed to the hydrophobic interaction and hydrogen bonding. The emulsion gels with different textures, rheology properties, and microstructures could be fabricated through adjusting the formulations (WPI concentration, κ-CG concentration, and oil phase fraction) as well as processing under different conditions (pressure and time). Afterward, curcumin-loaded emulsion gels were fabricated and subjected to an in vitro simulated gastrointestinal digestion in order to investigate the gastrointestinal fate of curcumin. In vitro simulated digestion results demonstrated that the UHP treatment significantly retarded the release of curcumin but had little impact on the bioaccessibility of curcumin. The results in this work provide useful information for the construction of emulsion gels through a non-thermal process, which showed great potential for the delivery of heat-sensitive bioactive components.