Effect of Pressure and Fat Content on Particle Sizes in Microfluidized Milk

Abstract

Average diameters and particle size distributions in fluid milks with different fat contents and subjected to various homogenization pressures with a "microfluidizer" were evaluated. Skim, 2%, and whole milks were microfluidized at 50, 100, 150, and 200 MPa. Cream containing 41% milk fat was microfluidized at 50, 100, and 150 MPa. Particle sizes were determined by laser light scattering. As microfluidization pressure was increased from 50 to 100 MPa, particle sizes in skim, 2%, and whole milks decreased. Microfluidization at pressures greater than 100 MPa had little additional effect on reducing the particle sizes in skim and 2% milks compared with microfluidization at 100 MPa, but the particle sizes in whole milk increased as the microfluidization pressure was increased from 100 to 200 MPa due to formation of homogenization clusters. The particle sizes in cream increased as the microfluidization pressure was increased from 50 to 150 MPa. When the microfluidization pressure was held constant, the particle sizes increased as the milk fat concentration was increased. The coefficients of variations of the volume-weighted particle size distributions for cream were higher than for skim, 2%, and whole milks. Larger "big" particles and smaller "small" particles were formed in whole milk after microfluidization at 200 MPa than at 100 MPa. Although microfluidization can be used to produce small particles in skim, 2%, and whole milks, a higher than optimum pressure (above 100 MPa) applied to whole milk will not lead to the minimum d(43) (volume-weighted average diameter) due to formation of clusters.

Acid coagulation properties and suitability for yogurt production of cows’ milk treated by high-pressure homogenisation

“…The size distribution curve (not shown) of milk treated at 200 MPa was characterised by a unique peak that corresponded to d 3.2 and d 4.3 in the range of 0.12-0.16 and 0.15-0.21 mm, respectively, depending on the inlet temperature. Above 200 MPa, the fat globule/particle size patterns corresponded to polydisperse distributions, as previously described by several authors (Desrumaux & Marcand, 2002;Thiebaud et al, 2003;Olson et al, 2004). In the range 230-330 MPa, the formation of large particles or fat aggregates was reflected in higher d 4.3 values and in broader size distributions.…”

“…Milk samples were diluted until obscuration of 2% or 10%, depending on the sample, and tempered to 37 1C. Fat globule/particle size determinations were carried-out at pump speed of 20% and using a refractive index of 1.471 (Olson, White, & Richter, 2004) corresponding to the dispersing phase, and 1.33, corresponding to water. Fat globule/particle size distribution was characterized by the Sauter mean diameter, d 3.2 (particle diameter that has the same specific surface as that of the full distribution) and by the d 4.3 (diameter of the spheres of equivalent volume to measured particles; this parameter is very sensitive to the presence of small amounts of large particles).…”

Effectiveness of encapsulating biopolymers to produce sub-micron emulsions by high energy emulsification techniques

“…Some workers believe Microfluidization is superior because, EDS distributions appeared to be narrower and smaller in Microfluidized emulsions than in the traditional emulsifying devices (Dalgleish, Tosh, & West, 1996;Pinnamaneni, Das, & Das, 2003;Robin, Blanchot, Vuillemard, & Paquin, 1992;Strawbridge, Ray, Hallett, Tosh, & Dalgleish, 1995). It is shown, however, that Microfluidization is unfavourable in specific circumstances such as higher pressures and longer emulsification times, as it leads to ''over-processing'', which is re-coalescence of emulsion droplets (Jafari, He, & Bhandari, 2006a, in press;Lobo & Svereika, 2003;Olson, White, & Richter, 2004).…”

Efficient Preparation of Liposomes Encapsulating Food Materials Using Lecithins by a Mechanochemical Method

“…On the other hand, microfluidization 19,20) allows the ink industry and pharmaceutical industry to obtain different formulations, from emulsions and suspensions to nanoparticles, and is thus often employed for the production of liposomes 21,22) . This mechanochemical method is readily available with a commercial ultra high-pressure homogenizer and needs no organic solvents.…”