Increasing Homogenization Pressure Research Articles

Gelation of oil-in-water emulsions stabilized by whey protein

The effects of heat treatment and high-pressure homogenization on whey protein (WP) emulsion properties were evaluated. Only emulsion containing non-heated WP was stable, presenting low viscosity, small droplets and higher adsorbed protein content by increasing homogenization pressure. In addition, the influence of high-pressure homogenization and pH on cold-set gel formation by acidification of emulsion (emulsion gel) or emulsion dispersed in heat-treated WP solution (emulsion-filled gel) was studied. Only emulsion-filled gels were self-supported. Stronger gels were observed at pH near WP isoelectric point due to lower acidification rate and electrostatic repulsion that promoted more intense protein aggregation. Varying emulsion homogenization pressure resulted in different gel network strength caused by changing dispersed phase volume fraction and adsorbed protein content. Therefore, depending on process conditions cold-set gel of emulsion can be produced and it shows a great potential to be used in food formulations as texturizing agent and/or as a carrier for heat-labile ingredients.

Optimization of Nanoemulsion Fabrication Using Microfluidization: Role of Surfactant Concentration on Formation and Stability

Nanoemulsions have some important potential advantages over conventional emulsions for certain commercial applications due to their optical clarity, high physical stability, and ability to increase the bioavailability of lipophilic bioactives. In this study, the factors influencing droplet size and stability in nanoemulsions fabricated from a hydrocarbon oil and an anionic surfactant were examined. Octadecane oil-in-water nanoemulsions were produced by a high pressure homogenizer (microfluidizer) using sodium dodecyl sulfate (SDS) as a model anionic surfactant. The influence of homogenization pressure, number of passes, and surfactant concentration was examined. The droplet size decreased with increasing homogenization pressure, number of passes, and surfactant concentration. Nanoemulsions with low turbidity and small droplet diameters (≈62 nm) could be produced under optimized conditions. Interestingly, nanoemulsions containing relatively high surfactant levels were highly susceptible to creaming when they were only passed through the homogenizer a few times, which was attributed to depletion flocculation. These results show the importance of optimizing surfactant levels to produce small droplets that are also stable to creaming.

Effect of high-pressure homogenization preparation on mean globule size and large-diameter tail of oil-in-water injectable emulsions

The effect of different high pressure homogenization energy input parameters on mean diameter droplet size (MDS) and droplets with > 5 μm of lipid injectable emulsions were evaluated. All emulsions were prepared at different water bath temperatures or at different rotation speeds and rotor-stator system times, and using different homogenization pressures and numbers of high-pressure system recirculations. The MDS and polydispersity index (PI) value of the emulsions were determined using the dynamic light scattering (DLS) method, and large-diameter tail assessments were performed using the light-obscuration/single particle optical sensing (LO/SPOS) method. Using 1000 bar homogenization pressure and seven recirculations, the energy input parameters related to the rotor-stator system will not have an effect on the final particle size results. When rotor-stator system energy input parameters are fixed, homogenization pressure and recirculation will affect mean particle size and large diameter droplet. Particle size will decrease with increasing homogenization pressure from 400 bar to 1300 bar when homogenization recirculation is fixed; when the homogenization pressure is fixed at 1000 bar, the particle size of both MDS and percent of fat droplets exceeding 5 μm (PFAT5) will decrease with increasing homogenization recirculations, MDS dropped to 173 nm after five cycles and maintained this level, volume-weighted PFAT5 will drop to 0.038% after three cycles, so the “plateau” of MDS will come up later than that of PFAT5, and the optimal particle size is produced when both of them remained at plateau. Excess homogenization recirculation such as nine times under the 1000 bar may lead to PFAT5 increase to 0.060% rather than a decrease; therefore, the high-pressure homogenization procedure is the key factor affecting the particle size distribution of emulsions. Varying storage conditions (4–25°C) also influenced particle size, especially the PFAT5.

Analysis of the Effect of High‐Pressure Homogenization (HPH) on the Settling Velocity of Particles in an Alcoholic Rice Beverage Using Video Recording, Turbidity and Computational Fluid Dynamic Simulation

AbstractHigh‐pressure homogenization (HPH) was applied to an alcoholic rice beverage (ARB). The effects of pressure (48–172 MPa) and the number of passes (1–3) on the fluid properties of the ARB, such as particle size, viscosity, turbidity and settling velocity, were investigated. Mean diameters continuously decreased with increasing homogenization pressure (P) and pass number (PN) until it reached a saturated condition (172 MPa with PN = 2). The viscosity and volume fraction of ARBs proportionally increased with increasing P and PN. The turbidity of HPH‐treated samples had stable characteristic until approximately 40 min. The settling velocities estimated by three different methods, including video recording, computational fluid dynamics simulation and analytic solutions (free and hindered flow). The free and hindered settling velocity of nonhomogenized and HPH‐treated samples were in the range of 1.2 × 10−4 to 1.7 × 10−4 and 0.3 × 10−7 to 4.3 × 10−7 m/s, respectively.Practical ApplicationFor alcoholic rice beverages (ARB), the unique translucent milky color differentiates ARB from distilled alcoholic beverage. The translucency is mainly due to the solid particles in the ARB, which could not be completely separated by the coarse filtration. Settling of solid particles caused a phase separation of ARB during storage or even serving in the glass. Our study showed that the high‐pressure homogenization (HPH) dramatically reduced the particle size of the ARB. Consequently, the settling velocity of HPH‐treated samples were significantly lower than that of nonhomogenized (NH) sample. The phase separation of ARB was delayed significantly after HPH.

고압 균질기를 이용한 커큐민 함유 나노에멀젼의 제조

Curcumin is a natural polyphenolic compound with a variety of beneficial activities. However, its application as a functional ingredient is currently limited because of its poor aqueous solubility and bioavailability. In this study, oilin-water nanoemulsions containing curcumin were prepared by microfluidization to improve solubility and bioavailability of curcumin. The effects of emulsifier type and concentrations, the homogenizing pressure (40-140 MPa) and number of cycles on particle size parameters and stability of nanoemulsions were investigated. The results showed that particle size of the nanoemulsion was considerably decreased from 126 nm to 55 nm with increasing homogenization pressure, number of cycles and emulsifier concentration. The optimum conditions for nanoemulsion preparation were determined to be homogenization pressure of 120 MPa and 3 cycles. The storage study showed that the curcumin nanoemulsions were physically stable for about 8 weeks at room temperature.

Processing Frozen Concentrated Orange Juice (FCOJ) by High Pressure Homogenization (HPH) Technology: Changes in the Viscoelastic Properties

The rheological properties of a fluid have an important role in process development and optimization. Due to its high concentration, frozen concentrated orange juice (FCOJ) shows viscoelastic behaviour, especially at low temperatures. In this study, high pressure homogenization (HPH) processing (0, 25, 50, 75, 100 and 150 MPa) was used to change the viscoelastic properties of FCOJ. The rheological behaviour of the FCOJ, before and after HPH processing, was evaluated using dynamic frequency sweep procedures. The storage (G′) and loss (G″) moduli were modelled as a function of the oscillatory frequency using the power law. The sample processed at 0 MPa showed G′ > G″. On the other hand, all other samples presented G″ > G′. Both the elastic and viscous behaviours decreased with increasing homogenization pressure. The power law parameters were then modelled as a function of the homogenization pressure using exponential functions. Also, the Cox–Merz rule was verified for all the samples, showing good applicability when a linear mathematical modification was applied. The reduction in the elastic and viscous components was explained by the reduction in particle size and molecular size of the serum constituents. A decrease in viscoelasticity leads to less resistance to flow and therefore to lower energy costs for the FCOJ process. These results are useful to understand the phenomena leading to an industrial application of this technology.

High pressure homogenization to improve the stability of casein–hydroxypropyl cellulose aqueous systems

The effect of high pressure homogenization on the improvement of the stability hydroxypropyl cellulose (HPC) and micellar casein was investigated. HPC with two molecular weights (80 and 1150 kDa) and micellar casein were mixed in water to a concentration leading to phase separation (0.45% w/v HPC and 3% w/v casein) and immediately subjected to high pressure homogenization ranging from 0 to 300 MPa, in 100 MPa increments. The various dispersions were evaluated for stability, particle size, turbidity, protein content, and viscosity over a period of two weeks and Scanning Transmission Electron Microscopy (STEM) at the end of the storage period. The stability of casein–HPC complexes was enhanced with the increasing homogenization pressure, especially for the complex containing high molecular weight HPC. The apparent particle size of complexes was reduced from ∼200 nm to ∼130 nm when using 300 MPa, corresponding to the sharp decrease of absorbance when compared to the non-homogenized controls. High pressure homogenization reduced the viscosity of HPC–casein complexes regardless of the molecular weight of HPC and STEM imagines revealed aggregates consistent with nano-scale protein polysaccharide interactions.

Formation of nanoemulsions stabilized by model food-grade emulsifiers using high-pressure homogenization: Factors affecting particle size

Nanoemulsions are finding increasing utilization in the food and beverage industries for certain applications because of their unique physicochemical and functional properties: high encapsulation efficiency; low turbidity; high bioavailability; high physical stability. In this study, we examined the impact of system composition and homogenization conditions on the formation of nanoemulsions using a high-pressure homogenizer (microfluidizer). The mean particle diameter decreased with increasing homogenization pressure and number of passes, with a linear log–log relationship between mean particle diameter and homogenization pressure. The minimum droplet diameter that could be produced after 6 passes at 14kbar depended strongly on emulsifier type and concentration: SDS<Tween 20<β-lactoglobulin<sodium caseinate. Small-molecule surfactants formed smaller droplets than proteins, which was attributed to their ability to rapidly adsorb to the droplet surfaces during homogenization. The impact of phase viscosity was examined by using different octadecane-to-corn oil ratios in the oil phase and different glycerol-to-water ratios in the aqueous phase. The minimum droplet size achievable decreased as the ratio of disperse phase to continuous phase viscosities (ηD/ηC) decreased for SDS-stabilized emulsions, but was relatively independent of ηD/ηC for β-lactoglobulin-stabilized emulsions. At low viscosity ratios, much smaller mean droplet diameters could be achieved for SDS (d∼60nm) than for β-lactoglobulin (d∼150nm). The information reported in this study will facilitate the rational design of food-grade nanoemulsions using high-pressure homogenization methods.

Effects of high pressure homogenization on rheological properties of flaxseed gum

The effects of high pressure homogenization on the rheological properties of flaxseed gum solution were analyzed in this study. The apparent viscosity of flaxseed gum was decreased by increasing homogenization pressure, while the temperature of the solution was gradually increased at the same time. The consistency index and the flow behavior index in the Power Law model of apparent viscosity were also modeled with Power Law and logarithm equations, respectively. The decay in parameters of storage and loss modulus model was also found along with the increasing homogenization pressure. Although no effect of pressure on conductivity and gelling temperature was significant, the clarity of the flaxseed gum was increased by increasing pressure. The activation and zeta potential of the flaxseed gum showed similar trends with the homogenization pressure, which were first increased then decreased from 30 MPa.

Changes in the surface protein of the fat globules during homogenization and heat treatment of concentrated milk

The changes in milk fat globules and fat globule surface proteins of both low-preheated and high-preheated concentrated milks, which were homogenized at low or high pressure, were examined. The average fat globule size decreased with increasing homogenization pressure. The total surface protein (mg m-2) of concentrated milk increased after homogenization, the extent of the increase being dependent on the temperature and the pressure of homogenization, as well as on the preheat treatment. The concentrates obtained from high-preheated milks had higher surface protein concentration than the concentrates obtained from low-preheated milks after homogenization. Concentrated milks heat treated at 79 degrees C either before or after homogenization had greater amounts of fat globule surface protein than concentrated milks heat treated at 50 or 65 degrees C. This was attributed to the association of whey protein with the native MFGM (milk fat globule membrane) proteins and the adsorbed skim milk proteins. Also, at the same homogenization temperature and pressure, the amount of whey protein on the fat globule surface of the concentrated milk that was heated after homogenization was greater than that of the concentrated milk that was heated before homogenization. The amounts of the major native MFGM proteins did not change during homogenization, indicating that the skim milk proteins did not displace the native MFGM proteins but adsorbed on to the newly formed surface.

Preparation and Characterization of Water/Oil and Water/Oil/Water Emulsions Containing Biopolymer-Gelled Water Droplets

The purpose of this study was to create water-in-oil (W/O) and water-in-oil-in-water (W/O/W) emulsions containing gelled internal water droplets. Twenty weight percent W/O emulsions stabilized by a nonionic surfactant (6.4 wt % polyglycerol polyricinoleate, PGPR) were prepared that contained either 0 or 15 wt % whey protein isolate (WPI) in the aqueous phase, with the WPI-containing emulsions being either unheated or heated (80 degrees C for 20 min) to gel the protein. Optical microscopy and sedimentation tests did not indicate any significant changes in droplet characteristics of the W/O emulsions depending on WPI content (0 or 15%), shearing (0-7 min at constant shear), thermal processing (30-90 degrees C for 30 min), or storage at room temperature (up to 3 weeks). W/O/W emulsions were produced by homogenizing the W/O emulsions with an aqueous Tween 20 solution using either a membrane homogenizer (MH) or a high-pressure valve homogenizer (HPVH). For the MH the mean oil droplet size decreased with increasing number of passes, whereas for the HPVH it decreased with increasing number of passes and increasing homogenization pressure. The HPVH produced smaller droplets than the MH, but the MH produced a narrower particle size distribution. All W/O/W emulsions had a high retention of water droplets (>95%) within the larger oil droplets after homogenization. This study shows that W/O/W emulsions containing oil droplets with gelled water droplets inside can be produced by using MH or HPVH.

Characterization and acid-induced gelation of butter oil emulsions produced from heated whey protein dispersions

Whey protein isolate was dispersed at 4% or 8% (w/v) and heated at neutral pH to produce protein polymers. Butter oil, up to 20%, was homogenized in heated whey protein dispersions at pressure ranging from 10 to 120 MPa. Emulsion gelation was induced by acidification with glucono- δ-lactone. Whey protein polymers produced finely dispersed emulsions with fat droplet diameter ranging from 340 to 900 nm. Homogenization pressure was the main factor influencing droplet size. At low fat volume fraction, the emulsions exhibited Newtonian behaviour. As fat content increased, shear thinning behaviour developed as a result of depletion flocculation. Emulsion consistency index increased with protein and fat concentrations. Increasing homogenization pressure had no effect on Newtonian emulsions but promoted flocculation and significantly increased the consistency of high fat emulsions. Protein concentration was the main factor explaining emulsion gel hardness and syneresis. Syneresis decreased with increasing fat content in the gel.

Microencapsulating Properties of Whey Protein Concentrate 75

ABSTRACT Emulsions containing various levels of soya oil dispersed in solutions of whey protein concentrate (WPC) 75 (5% w/v) were spray‐dried to yield powders with oil contents ranging from 20% to 75% (w/w). The effect of homogenizing pressure and oil/protein ratio on oil globule size distributions and protein load of the emulsions and the microencapsulation efficiency (ME) and redispersion behavior of the powders were examined. Emulsion oil droplet size decreased with increasing homogenization pressure but was not affected by oil/protein ratio. Emulsion protein load and ME of the powders were negatively correlated with increasing oil/protein ratio. Powders with an oil/protein ratio &lt; 0.75 were least susceptible to destabilization during spray‐drying.

Microencapsulating properties of sodium caseinate.

Emulsions were prepared with 5% (w/v) solutions of sodium caseinate (Na Cas) and soy oil at oil/protein ratios of 0.25-3.0 by homogenization at 10--50 MPa. Emulsions were spray-dried to yield powders with 20--75% oil (w/w). Emulsion oil droplet size and interfacial protein load were determined. Microencapsulation efficiency (ME), redispersion properties, and structure of the powders were analyzed. The size of emulsion oil droplets decreased with increasing homogenization pressure but was not influenced by oil/protein ratio. Emulsion protein load values were highest at low oil/protein ratios. ME of the dried emulsions was not affected by homogenization pressure but decreased from 89.2 to 18.8% when the oil/protein ratio was increased from 0.25 to 3.0, respectively. Mean particle sizes of reconstituted dried emulsions were greater than those of the original emulsions, particularly at high oil/protein ratios (>1.0), suggesting destabilization of high-oil emulsions during the spray-drying process.

Highly sensitive discrimination of taste of milk with homogenization treatment using a taste sensor

The taste of milk with homogenization treatment was discriminated using a taste sensor. The transducer is composed of seven electrodes with lipid/polymer membranes. Sensory evaluations by humans for expressing taste characteristics of “richness” showed that there were no significant differences among the milk samples, which were treated with different homogenization pressure; on the contrary, it was possible to discriminate the slight differences in quality of milk with the taste sensor. The response electric potential pattern was much different below and above 100 kg cm −2 of homogenization pressure. The electric potential decreased systematically with increasing homogenization pressure higher than 100 kg cm −2. The distribution of fat globule size had two peaks with homogenization pressure below 100 kg cm −2, but had one peak over 100 kg cm −2. Thus, the taste sensor responds to some physico-chemical changes accompanied by change in globule size and has the discrimination ability superior to humans. The present result will contribute to automated real-time control of homogenization of milk.

Performance of Homogenizers in Infrared Milk Analyzers: A Survey

Abstract The objective of this survey was to determine if infrared milk analyzers can achieve a &amp;lt;0.05% difference in fat test between unhomogenized and homogenized portions of the same milk, as stated in official methods. Two batches of pasteurized, unhomogenized milk (3 and 6% fat) were prepared from a single source of raw cream and skim. Homogenized milks were produced at 3 pressures: 0, 10342, and 17238 kPa. Pairs of unhomogenized and homogenized portions of the same milk were tested on 22 infrared analyzers. More instruments exceeded the 0.05% difference between homogenized and unhomogenized milk than expected; differences between homogenized and unhomogenized milk increased with increasing homogenization pressure and fat concentration. At 3% fat, differences between homogenized and unhomogenized milks at both 10342 and 17238 kPa were &amp;lt;0.05% for 21 of 22 instruments for fat A; only 17 and 13 of 22 instruments for fat B achieved a difference of &amp;lt;0.05% at 10342 and 17238 kPa, respectively. At 6% fat, differences between homogenized and unhomogenized milks for fat A were &amp;lt;0.05% for 15 and 14 of 22 instruments at the 2 pressures, respectively. For fat B, 8 and 5 of 22 instruments achieved a difference of &amp;lt;0.05% at 10432 and 17238 kPa. Instruments were also evaluated for homogenization efficiency by a revised criterion that is dependent on the fat content of the samples used for the evaluation.

Free Fat in Foam-Dried Whole Milk

Summary Concentrates of 50% T. S. were foamed and dried in a vacuum shelf drier, and comminuted through a 20-mesh screen, Methods were developed for determination of free fat (by extraction with carbon tetrachloride) and of that fat readily separated by centrifugation of the reconstituted product. Large increases in free fat (from 10 to over 90% of the total fat) resulted from aging and lactose crystallization of the concentrate. This effect was reversed by heating immediately before drying. Free fat decreased slightly with increasing homogenization pressure. Free fat contents less than 10% of the total fat were obtained by proper control of these factors. Dispersibility of the dry milk decreased slightly with increase in free fat. The fat rise under centrifugal force in reconstituted milk was not affected by variation in free fat to about 50%. At high free fat levels, part of the fat was readily separated by centrifugation. Free fat increased with decrease in particle size. A fraction obtained by comminution through a 40-mesh screen, followed by removal of the finest particles by sieving on a 60-mesh screen, was similar in free fat, more dispersible, and much higher in bulk density when compared to the product obtained by comminution through a 20-mesh screen.