Changes in milk fat globules and membrane lipids under the shear fields of microfiltration and centrifugation

Abstract

This study compared the efficiency of centrifugal and microfiltration separation of milk fat globules (MFG) from bovine cream and the changes that take place in the corresponding lipid membranes (MFGM). Creams were washed with water (1:10) and subjected to either centrifugation or microfiltration to fractionate proteins and other non-fat milk components. Protein analyses of the obtained fractions were carried out by gel electrophoresis. Lipid extraction and thin layer chromatography were also employed to separate lipid types and the amount of polar lipids were determined by gas chromatography. The effect of flow conditions on MFG's colloidal properties and MFGM components was evaluated based on estimates of the average rate of energy dissipation in microfiltration and centrifugation processes. Both were equally effective in removing the protein fraction (93% yield) as well as non-fat dry matter (~100% removal). Microfiltration reduced the mean particle size by 0.3 µm, whereas the opposite was observed for centrifugal separation (average size increase by 0.8 µm). The latter process also induced a more significant reduction in the electrostatic charges (zeta potential) of the colloids in the cream, which relates to the changes in the milk fat globule surface composition and the release of MFGM components. The dissociated polar lipids amounted to 24% and 20% upon centrifugation and microfiltration, respectively. Overall, the results suggest that MFG and MFGM are partially damaged under the shear forces typical of centrifugal and microfiltration separation. A high separation efficiency, with minimal fat globule damage and high MFGM yield is possible by adopting microfiltration under carefully optimized conditions.

Partitioning of the milk fat globule membrane between buttermilk and butter serum is determined by the thermal behaviour of the fat globules

“…Filtration was carried out as described previously (Jukkola et al, 2019) using a uniform transmembrane pressure (UTP) filtration system (Tetra Alcross®, Tetra Pak, Denmark) equipped with multichannel tubular ceramic membranes, with 1.4 μm pore size and 0.24 m 2 filtration surface area (Membralox®, Pall Corporation, France). Ten kilograms of cream were diluted (1:10) with deionised water and preheated to 50 °C.…”

“…Removal of major milk proteins by cream washing prior to butter making has been proposed to increase the yield of MFGM in the buttermilk and butter serum dry matter (Jukkola et al, 2019;Lamothe, Robitaille, St-Gelais, & Britten, 2008;Morin, Britten, Jiménez-Flores, & Pouliot, 2007). However, cream washing by microfiltration was reported to reduce also cream MFGM content, that was accompanied by a corresponding increase in small lipid droplets and membrane fragments in the wash solution (Jukkola et al, 2019;Lamothe et al, 2008). When the distribution of MFGM components in the buttermilk and butter serum was investigated, the buttermilk MFGM content was observed to be lower upon cream washing (Lamothe et al, 2008).…”

Milk fat globule membrane: An overview with particular emphasis on its nutritional and health benefits

“…Due to its amphiphilicity and role as a stabiliser for fat globules, MFGM is considered to be a suitable food emulsifier (Jukkola et al . 2019a). In addition, liposomes can be prepared from MFGM‐phospholipids to be used as a delivery vehicle for hydrophilic and hydrophobic bioactive molecules (Arranz and Corredig, 2017).…”

Microfiltration of raw milk for production of high-purity milk fat globule membrane material

“…Still, 24% was a surprisingly high amount considering that 97% of all caseins were transferred to permeate during the preceding filtration (Table 1). Jukkola et al (2019) observed that even after three microfiltration cycles of cream, 34% of the cream proteins were still made up of caseins, and ascribed this to the pasteurisation step (75 °C, 20 s) preceding microfiltration. While this may be partly true due to slightly higher pasteurization temperature and time, the present results, where pasteurization order showed no effect, suggested an alternative explanation for the contamination of MFGM with caseins.…”