Characterization of β-carotene nanoemulsion–loaded hydrogel particles formed via quince seed mucilage–whey protein isolate coacervation

RuBisCO was extracted from sugar beet leaves using soft and food-compatible technologies. Proximate composition, solubility, emulsifying, foaming and gelling properties of the protein isolate were determined. All these properties were systematically benchmarked against commercial whey and soy protein isolates used in food applications. RuBisCO protein isolate (RPI) contained 930 g kg-1 of crude protein. Protein solubility was higher than 80% at pH values lower than 4.0 or higher than 5.5. Foaming capacity of RPI was better at pH 4.0 than at pH 7.0. Interestingly, 10 g kg-1 protein foams were more stable (pH 7.0 and 4.0) than foams obtained with whey or soy protein. Moreover, 10 g kg-1 RPI emulsions at pH 4.0 or 7.0 exhibited good stability, being similar to whey protein isolate. Remarkable gelling properties were observed at pH 7.0, where 50 g kg-1 protein solutions of RPI formed self-supporting gels while more concentrated solutions were needed for whey or soy protein. RuBisCO showed comparable or superior functional properties to those of currently used whey and soy protein isolates. These results highlight the high potential of sugar beet leaf protein isolate as a nutritious and functional food ingredient to face global food security and protein supply. © 2018 Society of Chemical Industry.

To examine the effect of protein adsorption on the fat–water interface on the surface composition of spray-dried particles, whey, hydrolyzed whey, and soy protein isolate emulsions were prepared at three different protein to fat ratios of 1:1, 1:5, and 1:10 and spray dried. Non-hydrolyzed whey protein isolate (WPI) and the more hydrolyzed whey protein solutions at 20.2% degree of hydrolysis (DH) had significantly lower surface tension values with fat than without fat. The correlation between the reduction of surface tension value of an emulsion and the increase in protein surface composition of powder particles was observed for WPI and HWP406 but was not observed for the other protein isolate types. It was clear that the spray-dried emulsions had fat as the dominant component on the surface of the powder particles and that the amount of protein on the surface became severely depressed at higher fat addition levels. In terms of its powder morphology, the unique powder structures such as the indentations and folds usually found on the surface of protein containing powders were not evident because they were compromised by the presence of high surface fat. The powder with higher surface fat had more crumpled particle structures and dimpled surfaces.

Bioactive compounds including polyphenols (PP) have been observed to naturally form non-covalent complexation interactions with proteins under mild pH and temperature conditions, affecting protein structures and functionality. Previously, addition of Aronia berry PP to liquid dispersions containing whey protein isolate (WPI) and sucrose was found to alter characteristics including viscosity, surface tension, and particle sizes, with changes being attributed to protein-PP interactions. In this study we aimed to investigate whether Aronia PP would interact with soy and pea protein isolates (SPI and PPI, respectively) to a similar extent as with WPI in liquid protein-sucrose-PP mixtures. We hypothesized that formulations containing PPI (comprised of larger proteins) and hydrolyzed SPI (containing more carboxyl groups) may exhibit increased viscosities and decreased aggregate sizes due to enhanced protein-PP interactions. Concentrated liquid dispersions of varied ratios of protein to sucrose contents, containing different protein isolates (WPI, SPI, and PPI), and varied Aronia PP concentrations were formulated, and physical properties were evaluated to elucidate the effects of PP addition. PP addition altered physical characteristics differently depending on the protein isolate used, with changes attributed to protein-PP interactions. SPI and PPI appeared to have higher propensities for PP interactions and exhibited more extensive shifts in physical properties than WPI formulations. These findings may be useful for practical applications such as formulating products containing fruit and proteins to obtain desirable sensory attributes.Graphical abstract

BackgroundConsumption of moderate amounts of animal-derived protein has been shown to differently influence skeletal muscle hypertrophy during resistance training when compared with nitrogenous and isoenergetic amounts of plant-based protein administered in small to moderate doses. Therefore, the purpose of the study was to determine if the post-exercise consumption of rice protein isolate could increase recovery and elicit adequate changes in body composition compared to equally dosed whey protein isolate if given in large, isocaloric doses.Methods24 college-aged, resistance trained males were recruited for this study. Subjects were randomly and equally divided into two groups, either consuming 48 g of rice or whey protein isolate (isocaloric and isonitrogenous) on training days. Subjects trained 3 days per week for 8 weeks as a part of a daily undulating periodized resistance-training program. The rice and whey protein supplements were consumed immediately following exercise. Ratings of perceived recovery, soreness, and readiness to train were recorded prior to and following the first training session. Ultrasonography determined muscle thickness, dual emission x-ray absorptiometry determined body composition, and bench press and leg press for upper and lower body strength were recorded during weeks 0, 4, and 8. An ANOVA model was used to measure group, time, and group by time interactions. If any main effects were observed, a Tukey post-hoc was employed to locate where differences occurred.ResultsNo detectable differences were present in psychometric scores of perceived recovery, soreness, or readiness to train (p > 0.05). Significant time effects were observed in which lean body mass, muscle mass, strength and power all increased and fat mass decreased; however, no condition by time interactions were observed (p > 0.05).ConclusionBoth whey and rice protein isolate administration post resistance exercise improved indices of body composition and exercise performance; however, there were no differences between the two groups.

Whey protein isolate (WPI) is high in vitamin B12 and folate. These and other related markers (holotranscobalamin, methylmalonic acid and homocysteine) have been linked with cognitive health. This study explored the efficacy of WPI for improving cognitive function via delivery of vitamin B12. Moderately vitamin B12-deficient participants aged between 45 and 75 years (n = 56) were recruited into this randomised controlled crossover trial. Participants (55% female) consumed 50 g whey (WPI; active) or soy protein isolate (SPI; control) for eight weeks. Following a 16-week washout phase, they consumed the alternative supplement. Consumption of WPI significantly improved active B12 and folate status but did not result in direct improvements in cognitive function. However, there was evidence of improvement in reaction time (p = 0.02) and reasoning speed (p = 0.04) in the SPI condition for females. Additional analyses showed that changes in active B12, HcY and folate measures during WPI treatment correlated with improvements in cognitive function (all p < 0.05). Results indicate that WPI itself did not result in improved cognitive function but some evidence of benefit of SPI for females was found. However, consistent with previous research, we present further evidence of a role for active B12, HcY and folate in supporting cognitive improvement in adults with low B vitamin status.

Partially replacing animal proteins with plant proteins to develop new products has much attention. To get knowledge of their application in emulsion gels, heat-induced composite protein emulsion gels were fabricated using the mixtures of whey protein isolate (WPI) and soy protein isolate (SPI) with the final total protein concentration of 10% (w/w). The water holding capacity (WHC), mechanical and rheological properties and microstructure of mixed protein emulsion gels prepared at different WPI to SPI ratios (100:0, 90:10, 70:30, 50:50, 30:70, 10:90, 0:100, w/w) were investigated. The ratios of WPI to SPI showed little effect on the WHC of the mixed protein emulsion gels (p > 0.05). Increasing the ratio of SPI decreased the hardness and storage modulus (G′) of mixed protein emulsion gels, whereas the porosity of mixed protein emulsion gels in the microstructure increased, as shown by CLSM. Both β-lactoglobulin and α-lactalbumin from WPI and 7 S and 11 S from SPI participated in forming the gel matrix of mixed protein emulsion gels. More protein aggregates existed as the gel matrix filler at the high soy protein levels. Interestingly, the G′ of mixed protein emulsion gels at the WPI to SPI ratio of 50:50 was higher than the sum of G′ of individual WPI and SPI emulsion gels. The whey protein network predominated the gel matrix, while soy protein predominated in the active filling effect. When subjected to an in vitro dynamic gastric digestion model, soy protein in the gels (WPI:SPI = 50:50) degraded faster than whey protein during gastric digestion. This study provided new information on the characteristics of composite protein emulsion gel fabricated with the WPI and SPI mixture.

Physicochemical properties of milk protein ingredients and their acid gelation behaviour in different ionic environments

Whey protein is widely used in the food industry as an emulsion stabilizer because of its outstanding emulsifying ability. Recent studies have shown that heat-induced whey protein aggregates may also have potential to stabilize emulsions. The interfacial behavior of whey protein and whey protein aggregates adsorbed at the milk fat-water interface has not been well investigated, especially not in the nonlinear regime, which is highly relevant for the preparation of products such as recombined dairy cream.In this study, the interfacial properties of milk fat-water interfaces stabilized by whey protein isolate (WPI) and whey protein aggregates (WPA) at different bulk concentrations (0.1 wt% - 4.0 wt%) were studied by Large Amplitude Oscillatory Dilatation (LAOD). Lissajous plots were used to analyse the nonlinear response of the interfaces as a function of strain amplitude and frequency. The elastic modulus was quantified based on the tangent modulus at zero instantaneous strain in expansion and in compression. Bulk stability of creams stabilized with the mentioned proteins was studied by determining creaming rate, droplet size distribution, ζ-potential and viscosity of the continuous phase.At low concentrations (<2.0 wt%), WPI-stabilized cream had smaller oil droplets than WPA-stabilized cream, indicating that at these concentrations WPI had better emulsifying ability. For concentrations higher than 2.0 wt%, WPA was a better emulsifier in terms of creaming stability because of the higher viscosity of the continuous phase of the emulsions. Both WPI and WPA could prevent coalescence equally well if the concentration was higher than 0.5 wt%. LAOD measurements showed that at a protein concentration of 0.1 wt%, there was little difference between WPI- and WPA-stabilized interfaces. At 4.0 wt%, WPI showed abrupt intra-cycle yielding followed by a predominantly viscous behavior at large expansion. The WPA interfacial layer had a larger maximum linear strain, and showed a more gradual softening in expansion and mild strain hardening in compression. We hypothesize that WPI formed denser and more brittle (quasi-) 2d structures at the interface, while the interfaces formed by WPA might have a thicker and more stretchable 3d structure. The WPA-stabilized emulsion was less resistant to coalescence upon drastic stirring, which can be explained with its different large deformation behavior, and is relevant for applications where the cream is subjected to large deformations (whipping or stirring).

Effect of structuring emulsion gels by whey or soy protein isolate on the structure, mechanical properties, and in-vitro digestion of alginate-based emulsion gel beads

This study investigated the extrusion-based 3D printability of heat-induced whey protein gels as protein rich food inks. In particular, the effects of ionic strength by the addition of NaCl (0–250 mM), protein content (10%, 15%, 20%), fat content (0%, 10%), and partial substitution of whey protein isolate (WPI) with microparticulated whey protein (MWP) or micellar casein isolate (MCI) on printability were assessed. Texture analysis, specifically Young’s modulus, rheological measurements including yield stress, and creep–recovery behavior were used to characterize the gels. Modifications of the formulation in terms of ionic strength, increased protein content, and the formation of emulsion gels were insufficient to maintain a continuous extrusion process or shape stability after printing. However, the substitution of WPI with MWP created more viscoeleastic gels with improved printability and shape retention of the 3D cube structure after deposition. The partial replacement of WPI with MCI led to phase separation and 3D-printed cubes that collapsed after deposition. A narrow range of rheological material properties make WPI and MWP emulsion gels promising food inks for extrusion-based 3D printing.

Supplementation of food with antioxidants may help to reduce oxidative stress in the body. Whey proteins are widely used in various foods for their nutritional, health promoting and functional value. One of the health promoting attributes of whey is its antioxidant activity. The objective of this study was to determine whether commercial whey protein isolate (WPI) maintains its antioxidant activity during upper gut transit and to identify the main whey protein responsible for this bioactivity. Individual whey proteins (β-lactoglobulin, α-lactalbumin, bovine serum albumin and lactoferrin) and WPI were subjected to static in vitro gastrointestinal digestion (SGID). Antioxidant activity of the proteins, pre and post SGID, were measured and compared using various antioxidant assays (ORAC, ABTS and FRAP). To determine whether WPI could boost intracellular antioxidant levels in intestinal epithelial cells, CaCo2 cells were exposed to SGID whey and intracellular glutathione levels quantified. Whey proteins, particularly α-lactalbumin (21.0% ABTS inhibition), exhibit antioxidant activities which are further enhanced during gut transit (37.3% ABTS inhibition, P 0.05). In conclusion, whey proteins exhibit antioxidant activities but their ability to boost intracellular antioxidant status of cells remains to be determined.

The objective of this study was to evaluate the potential of selected proteins as alternative materials for flavor encapsulation by spray drying. Two traditional materials (gum acacia and modified starch) and three proteins (sodium caseinate, whey and soy protein isolates) were used at different infeed solid levels; test compounds included (R)-(+)-limonene and three alpha,beta-unsaturated aldehydes ((E)-2-hexenal, (E)-cinnamaldehyde, citral). The primary criteria for performance were flavor retention during drying and protection against losses during storage. Limonene oxidation and nonenzymatic browning were investigated as two possible deterioration routes. Overall, higher infeed solids improved retention during drying and limited flavor losses (aldehydes and limonene) during storage in traditional materials only. The materials giving the highest flavor retention during drying were gum acacia (94%), modified starch (88%) and whey protein isolate (87%). Gum acacia provided the highest retention of aldehydes during storage (37 to 58%) after 28 days at 40 degrees C but did not afford good protection against limonene oxidation. Oppositely, protein materials effectively limited limonene oxidation (>70% retained). Nonenzymatic browning was observed for all powders prepared with proteins, especially whey protein isolate, whereas no browning occurred with traditional materials.

PURPOSE: The intake of whey protein is highly effective for accelerating muscle protein synthesis. Many studies have revealed that a rapid absorption rate and the leucine-rich amino-acid composition of whey protein contribute to the acceleration of muscle protein synthesis. Whey protein hydrolysates (WPH) have amino-acid composition identical to intact whey protein isolate (WPI) and are absorbed more rapidly than WPI. Our hypothesis was that WPH is a more potent accelerator for muscle protein synthesis than WPI. The aim of the present study was to compare the effects of WPH on muscle protein synthesis with WPI. METHODS: Male Sprague-Dawley (SD) rats swam for 2 h. Immediately after exercise, WPI was administered to the rats as a single dose (amounts of protein were 2.0 g/kg BW). Phe-D5 was injected via the tail vein 15 min before euthanasia for the measurement of the protein fractional synthesis rate (FSR). Rats were euthanized at designated postprandial time points (30, 60, 90 or 120 min) and triceps muscle samples were collected (n = 7-9/time point). FSR were measured to find out the time point at which FSR became highest. Subsequently, another group of male SD rats swam for 2 h. Immediately after exercise, WPH, WPI or deionized water (control, n = 8) was administered to the rats as a single dose (amounts of protein were 0.5 or 2.0 g/kg BW, n = 8/treatment/dose). Phe-D5 was injected via the tail vein 15 min before euthanasia. At the time point that the first study revealed postprandial FSR became highest, rats were anesthetized and their triceps muscles were excised to measure FSR. RESULTS: Postprandial FSR became highest at 60 min after WPI was administered (2.68+/-0.25, 3.64+/-0.19, 4.62+/-0.28, 4.19+/-0.21 and 3.99+/-0.19 %/day for 0, 30, 60, 90 and 120 min). 60 min after administration, WPH had significantly higher (p < 0.05) FSR compared to control at a dose of either 0.5 or 2.0 g/kg BW (5.21+/-0.22, 5.22+/-0.18 and 3.74+/-0.24 %/day for 0.5, 2.0 g/kg BW and control, respectively). However, WPI had significantly higher (p < 0.05) FSR compared to control only at a dose of 2.0 g/kg BW (4.51+/-0.10 and 5.09+/-0.20 for 0.5 and 2.0 g/kg BW). WPH had significantly higher (p < 0.05) FSR compared to WPI at 0.5 g/kg BW. CONCLUSIONS: Whey protein hydrolysates stimulate muscle protein synthesis at lower doses compared to intact whey protein.

Whey protein is a highly functional food ingredient used in a wide variety of applications. A large portion of fluid whey produced in the United States is derived from Cheddar cheese manufacture and contains annatto (norbixin), and therefore must be bleached. The objective of this study was to compare sensory and functionality differences between whey protein isolate (WPI) bleached by benzoyl peroxide (BP) or hydrogen peroxide (HP). HP and BP bleached WPI and unbleached controls were manufactured in triplicate. Descriptive sensory analysis and gas chromatography-mass spectrometry were conducted to determine flavor differences between treatments. Functionality differences were evaluated by measurement of foam stability, protein solubility, SDS-PAGE, and effect of NaCl concentration on gelation relative to an unbleached control. HP bleached WPI had higher concentrations of lipid oxidation and sulfur containing volatile compounds than both BP and unbleached WPI (P < 0.05). HP bleached WPI was characterized by high aroma intensity, cardboard, cabbage, and fatty flavors, while BP bleached WPI was differentiated by low bitter taste. Overrun and yield stress were not different among WPI (P < 0.05). Soluble protein loss at pH 4.6 of WPI decreased by bleaching with either hydrogen peroxide or benzoyl peroxide (P < 0.05), and the heat stability of WPI was also distinct among WPI (P < 0.05). SDS PAGE results suggested that bleaching of whey with either BP or HP resulted in protein degradation, which likely contributed to functionality differences. These results demonstrate that bleaching has flavor effects as well as effects on many of the functionality characteristics of whey proteins. Whey protein isolate (WPI) is often used for its functional properties, but the effect of oxidative bleaching chemicals on the functional properties of WPI is not known. This study identifies the effects of hydrogen peroxide and benzoyl peroxide on functional and flavor characteristics of WPI bleached by hydrogen and benzoyl peroxide and provides insights for the product applications which may benefit from bleaching.

Foods may contain more than one type of protein, and food formulators sometimes combine different proteins for desired synergistic textural benefits. Egg albumin, fish protein isolate, or soy protein isolate were blended with calcium caseinate or whey protein isolate and mixed in water adjusted to pH 2.5, 6.8, and 9.0 at 25 or 60°C. The effect of pH and temperature on solubility, viscosity, and the structure of the resulting gels were determined. The viscosity at the most soluble concentration at 25°C were: egg albumin (175.2 mPa.s/35 wt%), fish protein isolate (2207.4 mPa.s/30 wt%), soy protein isolate (2531.5 mPa.s/10 wt%), calcium caseinate (1115.8 mPa.s/15 wt%), and whey protein isolate (161.2 mPa.s/35%). In mixed protein systems viscosity values were reduced. The values for calcium caseinate or whey protein isolate with egg albumin, at the protein level of 15 g/100 g were: calcium caseinate/egg albumin (10:5 wt%) 535.1 mPa.s and whey protein isolate/egg albumin (10:5 wt%) 8.7 mPa.s. Microscopy imaging revealed changes in protein aggregation clusters during heating of calcium caseinate, egg albumin, and whey protein isolate. Egg albumin acted synergistically to increase viscosity, while fish protein isolate acted antagonistically to reduce viscosity. This knowledge is useful to manufacturers who may seek to enhance food texture by blending different proteins.