Microparticulated Whey Protein Research Articles

The Young's Modulus, Fracture Stress, and Fracture Strain of Gellan Hydrogels Filled with Whey Protein Microparticles.

Texture modifying abilities of whey protein microparticles are expected to be dependent on pH during heat-induced aggregation of whey protein in the microparticulation process. Therefore, whey protein microparticles were prepared at either pH 5.5 or 6.8 and their effects on small and large deformation properties of gellan gels containing whey protein microparticles as fillers were investigated. The majority of whey protein microparticles had diameters around 2 μm. Atomic force microscopy images showed that whey protein microparticles prepared at pH 6.8 partially collapsed and flatted by air-drying, while those prepared at pH 5.5 did not. The Young's modulus of filled gels adjusted to pH 5.5 decreased by the addition of whey protein microparticles, while those of filled gels adjusted to pH 6.8 increased with increasing volume fraction of filler particles. These results suggest that filler particles were weakly bonded to gel matrices at pH 5.5 but strongly at pH 6.8. Whey protein microparticles prepared at pH 5.5 showed more enhanced increases in the Young's modulus than those prepared at pH 6.8 at volume fractions between 0.2 and 0.4, indicating that microparticles prepared at pH 5.5 were mechanically stronger. The fracture stress of filled gels showed trends somewhat similar to those of the Young's modulus, while their fracture strains decreased by the addition of whey protein microparticles in all examined conditions, indicating that the primary effect of these filler particles was to enhance the brittleness of filled gels.

Short communication: Muscle protein synthetic response to microparticulated whey protein in middle-aged men

Whey protein concentrate (WPC) is a high-quality dairy ingredient that is often included in formulated food products designed to stimulate muscle anabolism. Whey protein concentrate can be affected by UHT processing, and its sensory properties are not compatible with some formulated food products. Microparticulated WPC (mWPC) is a novel ingredient that is resistant to heat treatment and has enhanced sensory properties. When 16 healthy middle-aged men consumed 20 g of either WPC or mWPC, both proteins increased plasma essential AA and leucine concentrations with no detectable difference in curve kinetics. Myofibrillar protein synthesis was increased in both groups for 90 min after ingestion with no difference between groups. Ingestion of mWPC resulted in a muscle anabolic response that was equivalent to that of WPC over the full 210-min measurement period. Formulated products incorporating mWPC or standard WPC would provoke equivalent anabolic responses.

Low‐fat Cheddar cheese made using microparticulated whey proteins: Effect on yield and cheese quality

Influence of different levels (0, 0.15, 0.35 or 0.50%) of microparticulated whey protein (MWP) on yield and quality of low‐fat (~7.3 g/100 g) Cheddar cheese was investigated. MWP improved cheese yield due to the water‐binding ability of denatured whey protein. MWP addition decreased meltability but improved the textural properties beneficial for shredding and slicing, by decreasing sensory firmness. The results emphasise the role of MWP as an inert filler within cheese matrix, in improving cheese yield and creating a softer texture without compromising the sensory or overall quality of cheese, even with moisture increases in 0.35 or 0.50% MWP cheeses.

Unravelling of the water-binding capacity of cold-gelated whey protein microparticles

Whey protein microparticles (CG MPs) were made with a cold gelation method. Without shearing or mixing during gelation spherical CG MPs were formed, while shearing or mixing resulted in smaller irregularly shaped CG MPs. The water-binding capacity of pellets (WBC-P) that were obtained after centrifuging CG MP dispersions was remarkably large (11–18 g water/g dry matter), though this value decreased at larger centrifugation speeds.Microscopy images hinted at the presence of two water domains in the CG MP pellets: water within and between the CG MPs. The images also imply that the amount of water within the CG MPs was determined by the centrifugation speed. The amount of water between CG MPs seemed to be defined by the amount of particle-particle interactions that were present, as suggested by the effects of the particles' size and the inhibition of the disulphide bridge formation on the WBC-P.Although microscopy images showed two water domains, only one main peak was found with time domain nuclear magnetic resonance. This was explained by water diffusion from one water domain to the other within the measuring time. This fast diffusion implies that the CG MPs had a relatively open structure. Overall, it was concluded that water-binding by CG MPs was affected by various factors and that a good understanding of the water-binding requires the use of a range of measurements.

Effects of added whey protein aggregates on textural and microstructural properties of acidified milk model systems

Non-fat milk model systems containing 5% total protein were investigated with addition of micro- or nanoparticulated whey protein at two levels of casein (2.5% and 3.5%, w/w). The systems were subjected to homogenisation (20 MPa), heat treatment (90 °C for 5 min) and chemical (glucono-delta-lactone) acidification to pH 4.6 and characterised in terms of denaturation degree of whey protein, particle size, textural properties, rheology and microstructure. The model systems with nanoparticulated whey protein exhibited significant larger particle size after heating and provided acid gels with higher firmness and viscosity, faster gelation and lower syneresis and a denser microstructure. In contrast, microparticulated whey protein appeared to only weakly interact with other proteins present and resulted in a protein network with low connectivity in the resulting gels. Increasing the casein/whey protein ratio did not decrease the gel strength in the acidified milk model systems with added whey protein aggregates.

Effect of microparticulated whey protein on sensory properties of liquid and semi-solid model foods

This work describes the sensory properties of microparticulated whey protein (MWP) particles in relation to their rheological and tribological properties. The aim of this work is to obtain a better understanding of the sensory perception of MWP particles compared to oil droplets in liquid and semi-solid matrices. We used liquid MWP-o/w emulsions with controlled viscosities and semi-solid MWP-emulsion-filled gelatin gels as food model systems.Consistent with our previous findings, MWP showed good lubrication properties probably due to ball bearing mechanism in both liquid and semi-solid systems. Sensory results (QDA) revealed that small MWP particles contributed to perception of creaminess due to their lubrication property. Large MWP contributed to the rough and powdery perception, and thus suppressed perception of creaminess. MWP did not contribute to perception of fattiness in contrast to oil droplets. The perception of fattiness was probably related to the film formation properties of oil. As a result, MWP in liquid emulsions were generally perceived as rough but not creamy. In the case of MWP-emulsion-filled gels, although the gel matrix restrained the lubrication function of MWP particles, it also masked the rough perception of big MWP particles. Due to the combined effect of both oil droplets and MWP particles, MWP in gels resulted in an overall positive effect on the creamy perception.We conclude that MWP contributes to fat-related sensations in a different way than oil does. The perception of MWP particles is related to the size of the particle as well as the properties of the surrounding matrix.

Effect of hydration of microparticulated whey protein ingredients on their gelling behaviour in a non-fat milk system

Two types of microparticulated whey protein ingredients with different particle characteristics were added to a non-fat milk system and allowed to hydrate for different periods of time prior to heat treatment. Differences during acidification of the milk systems were investigated by rheology and 1H nuclear magnetic resonance spin-spin relaxation. The amounts of more or less mobilised water were shown to differ depending on the type of microparticulated whey protein. Large protein microparticles did not actively participate in gel network formation and showed an increased fraction of more mobilised water, and thus higher syneresis upon storage. An enhanced surface reactivity was shown in small microparticles which may also be related to the increased interaction potential of the native whey proteins present.

An analytical approach to reveal the addition of heat-denatured whey proteins in lab-scale cheese making

A simple analytical procedure for the detection of self-aggregated heat-denatured whey proteins (HDWP) in model cheeses was developed. The principle of the approach lies in the solubilization of the cheese matrix by a sodium citrate solution (0.2 M, pH 7.0) resulting in the dissociation of the casein micelles and the insolubilization of HDWP aggregates, which are collected in the pellet after a centrifugation step. The reliability of the procedure was tested in lab-scale cheeses from peroxidase-positive pasteurized milk with different protein-based ingredients (microparticulated whey protein concentrate, milk protein concentrate, whey protein isolate and Ricotta cheese) at concentrations ranging from 0.2 to 1.2% protein (w/v on cheese milk). A linear relationship between the amount of the HDWP added to cheese milk and that recovered from model cheeses was observed. Heat-damage indicators, furosine and lysinoalanine, showed levels in the experimental cheese samples not related with added HDWP, but represented a source of information on the ingredients other than liquid milk. Overall, in the model cheeses, the proposed method was an easy-to-apply and reliable tool for the evaluation of the presence of HDWP-based products. Further investigation is required for the application to real cheeses and for the evaluation of possible interferences from proteolysis during ripening.

Combined Superfine Grinding and Heat-Shearing Treatment for the Microparticulation of Whey Proteins

Microparticulated proteins (MPPs) considerably improve the texture, taste and nutritional value of low-fat dairy products. A combination of superfine grinding and heat-shearing treatment was utilized in order to improve the processing adaptability and stability of microparticulated whey protein (MWP). Comparing the mean particle sizes of WPC and MWP with the superfine milled whey protein concentrate (sWPC) and its microparticulated whey protein (sMWP), the sWPC and sMWP were significantly decreased from 49.24 and 13.09 μm to 8.17 and 5.73 μm, respectively (P < 0.05). Both sWPC and sMWP exhibited higher water-holding capacity (1.9 and 3.69 g/g, respectively), emulsion activity index (146.38 and 128.6 m2/g, respectively), emulsion stability index (29.04 and 6.31, respectively) and viscoelasticity than WPC and MWP. The dispersion stability of sWPC, sMWP and its cream mimetic were also enhanced after superfine grinding treatment. The sMWP dispersion exhibited more stable liquid behaviour characteristics and maintained the creamy mouth feel better than MWP, indicating the higher dispersion stability of sMWP-based cream mimetic. Therefore, the combined superfine grinding and heat-shearing treatment is a promising technique for the production of microparticulated proteins.

Rheological characterization of full-fat and low-fat glaze materials for foods

The objective of this work was to perform the rheological characterization of full-fat and low-fat glaze materials used as film-forming fluids. Glaze materials were elaborated with icing sugar, skim milk powder, water, and different contents (0, 3, 6, and 9%) of vegetable fat (sunflower oil and soy lecithin) or microparticulated whey protein as fat mimetic. Rotational rheometry, creep tests, and dynamical rheometry were performed. Yield stress was obtained by direct and indirect methods. Steady shear viscosity was analyzed applying the Herschel–Bulkley model. Complex moduli were modeled with a power law equation and the application of Cox−Merz rule was considered. Images were obtained by optical microscopy. Average film thickness values were estimated using a mechanistic mathematical model for a dip-coating process during the draining stage. The results indicated that it may be possible to obtain low-fat glaze materials with rheological properties, microstructure, and film thickness-forming capacities similar to full-fat formulations.

Time domain nuclear magnetic resonance as a method to determine and characterize the water-binding capacity of whey protein microparticles

Water-binding capacity (WBC) is commonly measured with a centrifugation method in which a sample is hydrated in excess water and the pellet weight after centrifugation defines the WBC. When a dispersion is being analyzed, here containing whey protein microparticles (MPs), the pellet consists of swollen particles and water between the particles. These two water domains in MP pellets were distinguished using time domain nuclear magnetic resonance (TD NMR). This distinction showed that an increase in WBC from 2 to 5.5 g water/g dry matter was mainly due to an increase in water between the MPs. Besides, it was found that TD NMR-measurements could be used to provide accurate values of the amount of water in both water domains in MP pellets. This makes TD NMR therefore a more accurate method to determine the WBC of the whole pellet than weighing the pellet after centrifugation.

Effect of superfine grinding on the structural and physicochemical properties of whey protein and applications for microparticulated proteins

Effects of superfine grinding on structural and physicochemical properties of whey protein concentrate (WPC) and applications for microparticulated whey protein (MWP) were investigated. WPC and MWP particle sizes significantly (p<0.05) decreased after superfine grinding from 62 and 15 µm to 15 and 9 µm, respectively, compared with controls. A basis for exploration of WPC applications as a fat replacer because of WPC and MWP particle size reductions due to superfine grinding is established. The effect of superfine grinding on molecular configuration, thermal stability, and physicochemical properties of WPC were also investigated. Amounts of free sulfhydryl groups decreased significantly (p<0.05) from 18.16 to 14.49 µmol/L, and thermodynamic properties, including transition temperature, were changed after superfine grinding. The whey protein solubility, protein surface hydrophobicity, oil binding capacity, foaming capacity, and foaming stability of WPC were all improved after superfine grinding.

On enhancing the solubility of curcumin by microencapsulation in whey protein isolate via spray drying

The encapsulation of curcumin in whey protein microparticles by spray drying was done to improve solubility and thus, the bioavailability of curcumin. In solution, curcumin formed soluble complexes with whey protein isolate (WPI) via hydrophobic interactions and its solubility increased linearly with WPI concentrations. Solutions of WPI-curcumin complexes were spray-dried as uniform microparticles via a microfluidic jet spray dryer. Nearly 100% curcumin was retained in amorphous state and the microparticles could be easily rehydrated as transparent dispersions irrespective of the drying temperature. Antioxidant properties of these microparticles were studied by DPPH test, showing a higher DPPH radical scavenging activity for curcumin-loaded microparticles compared to that of WPI particles as benchmark. The ability to generate easily dissolved powders containing water-insoluble ingredients such as curcumin is a beneficial approach for pharmaceutical and functional foods applications.

Evidence for ball-bearing mechanism of microparticulated whey protein as fat replacer in liquid and semi-solid multi-component model foods

The current understanding of the mechanisms underlying the fat mimicking properties of fat replacers, such as microparticulated whey protein (MWP), is limited. MWP is known to provide fat-related mouth-feel in specific foods, such as yoghurts and cheeses.Tribological and rheological properties are well known to contribute to the perception of fat related sensory attributes. This study investigated the tribological and rheological properties of MWP in liquid and semi-solid model foods to reveal the mechanisms underlying the fat mimicking properties of MWP.In liquids, addition of MWP reduced the friction coefficient effectively. After scaling out the impact of viscosity on lubrication, results provide strong evidence that the reduction of friction of MWP in liquids is mainly due to ball-bearing lubrication. In semi-solid gels, addition of MWP also decreased the friction, but to a smaller extent compared to liquid model foods. The mechanism underlying the lubrication behavior of multi-component semi-solid foods that contain fat droplets, emulsifier, fat replacers such as MWP embedded in a gel matrix is complex. We conclude that different components affect the lubrication properties of the composite food through different mechanisms. Fat droplets reduce friction due to the formation of a fat film following a plate-out mechanism. We suggest that emulsifiers influence the formation of a fat or emulsifier film, whereas MWP is suggested to reduce friction due to a ball-bearing mechanism. In addition, the influence of bulk viscosity, gel fracture behavior, and the interactions between the MWP and its surrounding matrix and emulsifiers, need to be accounted for.

Properties of partially denatured whey protein products: Formation and characterisation of structure

Partially denatured whey protein (PDWPC) products have been manufactured using a controlled heating process that allows control of the degree of denaturation of the whey proteins. This is assessed by following the change in free sulphydryl content of the protein as heating progresses. This allows the formation of soluble whey protein aggregates of diverse particle size and morphology. The PDWPC's have been made using different manufacturing conditions (temperature, pH, degree of denaturation) to give aggregated PDWPC powders with a degree of denaturation in the range 45–98% and particle size 3–17 μm. Particle size analysis, scanning electron microscopy and density analysis show that the particles have aggregated structures that range from compact, particulate gel-like to fibrillar phase-separated structures, with intermediate structures formed under some conditions. These structures are consistent with the known gel structures formed in whey protein concentrate gels. The structure of the PDWPC particles differs from that of microparticulated whey proteins. The possibility of using PDWPC's as ingredients tailored to the needs of food manufacturers is discussed.

Rennet Coagulation and Cheesemaking Properties of Thermally Processed Milk: Overview and Recent Developments.

Thermally induced changes in milk proteins and minerals, particularly interactions among caseins and denatured whey proteins, influence important properties of dairy products in both positive and negative ways. Whereas the extensive protein connectivity and increased water-holding capacity resulting from such heat-induced protein modification account for the much desired firmness of acid gels of yogurt, thermal processing, on the other hand, severely impairs clotting and adversely affects the cheesemaking properties of rennet-coagulated cheeses. In technological terms, the principal ongoing challenge in the cheese industry is to take advantage of the water-holding capacity of thermally aggregated whey proteins without compromising the rennetability of cheese milk or the textural and functional attributes of cheese. Including some recent data from the authors' laboratory, this paper will discuss important aspects and current literature on the use of thermally processed milk in the production of rennet-coagulated cheeses and also some of the potential alternatives available for inclusion of whey proteins in cheese, such as the addition of microparticulated whey proteins to cheese milk.

Effect of microparticulated whey protein concentration and protein-to-fat ratio on Caciotta cheese yield and composition

The dairy industry exploits different processes to increase the value of whey protein (WP). Microparticulated whey proteins (MWP), which are colloidal particles formed by controlled aggregation of WP, are widely used in low-fat products. The aim of the present study was to evaluate the effects of MWP concentration (0.0–4.0%, v/v) and different protein-to-fat ratios (PFRs) on milk coagulation process, cheese yield and composition of Caciotta cheese. Samples of cheese were analysed after 10 d of ripening. The increment of PFR affected rennet coagulation time. Moreover, cheese yield decreased as the level of fat decreased, and it was greater in low-fat cheese (high PFR) with 4.0% MWP than in low-fat cheese with 3.0% MWP. No differences were detected for cheese yield in standard and high-fat cheese (standard and low PFR) across MWP concentrations. The stable composition of low-fat Caciotta suggests the possibility to include MWP as fat replacer.

Enhanced heat stability of high protein emulsion systems provided by microparticulated whey proteins

There is a desire to incorporate increasingly high concentrations of whey proteins into nutritional beverages to improve their nutritional content and amino acid profile. However, typical thermal treatments for sterility or extended shelf life cause undesirable aggregation/gelation of the whey proteins. To address this instability issue at high protein concentration, there is a need to develop new protein ingredient technologies that can provide resistance to heat-induced aggregation. In this study, the heat stability characteristics of model food emulsions containing standard or microparticulated whey protein concentrate (WPC80) were compared. Oil-in-water emulsions [10% (wt/wt) sunflower oil] containing increasing concentrations of protein (from 2 to 12 wt%) were prepared at pH 7.0. The effects of retorting at 120 °C for 10 min on particle size distribution, rheological properties, susceptibility to heat-induced coagulation, microstructure and surface protein concentration of the standard and microparticulated WPCs were compared. Also, various levels of NaCl were added to examine the heat stability of micro-aggregated WPC in the presence of additional salts.Microparticulated WPC emulsions showed significantly enhanced heat stability compared with standard WPC emulsions. Emulsions with up to 11 wt% protein and no visible aggregation or gelation after retorting were produced using microparticulated WPC. For standard WPC emulsions under the same heating conditions, large aggregates were formed and there was a change in flow behaviour to non-Newtonian at 3 wt% protein. With this specific technology, high protein whey-based nutritional beverages can be produced using conventional thermal treatments.

Textura y microestructura de quesos tipo panela bajos en grasa y en colesterol: diferentes metodologías

Three low-fat Panela cheeses were prepared from milk (13.5 g fat⋅L-1 milk) added with the following hydrocolloids: low methoxyl pectin (QPE), whey protein concentrate (QCP), and microparticulated whey protein (QPM). Additionally a low-fat Panela cheese was prepared from milk (6.75 g fat⋅L-1) incorporated with 6.1 g of emulsified canola oil in water⋅L-1 (QEM), and a low-fat Panela cheese was made from homogenized milk (13.5 g fat⋅L-1 milk) (QHM). As controls, a low-fat cheese (QBG) (13.5 g fat⋅L-1 milk), and a full-fat cheese (QCG) (27 g fat⋅L-1 milk) were prepared. After 48 h of manufactured, the different cheese treatments were subjected to chemical composition analysis, instrumental texture determination (Texture Profile Analysis), sensory texture evaluation (by a trained panel of judges), and microstructural analysis (Scanning Electron Microscopy). The QPE, QPM, and QEM cheeses had a relaxed, porous and open protein matrix associated with low values of hardness, springiness, cohesiveness, and chewiness; while the QBG and QHM cheeses showed a compact and dense protein matrix related with high values of hardness, springiness and chewiness. The QCP cheese presented instrumental textural characteristics comparable to those of the QCG cheese even though its protein matrix was apparently more compact and smoother than the corresponding to this latter. In general terms, the sensory texture characteristics correlated well with the instrumental textural characteristics.

Effect of crosslink density on the water-binding capacity of whey protein microparticles

The ability of whey protein microparticles (MPs) to bind water and consequently to swell is, amongst others, determined by the crosslink density of the MPs. The Flory-Rehner model states that a decrease in crosslink density should lead to an increased swelling of the MPs. Decreasing the crosslink density of MPs with dithiothreitol (DTT) decreased the amount of disulphide bridges and increased the water-binding capacity (WBC) from 6 to 9 g water/g protein. Increasing the crosslink density with transglutaminase or genipin resulted in a decreased number of primary amino groups, although the WBC did not change significantly. The WBC of the MPs was determined using a centrifugation method that resulted in the formation of a pellet, so water inside and between the MPs was measured simultaneously. Therefore, additional microscopy and swelling tests were performed, which suggested that an increased WBC of the pellet of MPs was not only related to an increased swelling of the MPs, but also to an increased amount of water between the MPs.