Combination of homogenization and cross-flow microfiltration to remove microorganisms from industrial buttermilks with an efficient permeation of proteins and lipids

• Homogenization of buttermilk induces structural rearrangements of MFGM fragments.
• Microfiltration allows the selective removal of bacteria from buttermilk.
• Efficient permeation of polar lipids and proteins
• Improved safety of buttermilk-based ingredients for human nutrition

Buttermilk is a source of interesting nutritional and functional components, e.g. polar lipids and proteins. However, it is still considered as a low-value by-product of the dairy industry with high variations in biochemical composition and bacterial contaminations. The objective of this study was to develop a process based on microfiltration, permitting the removal of microorganisms to ensure the safety of buttermilk components for human nutrition. Industrial buttermilks and the products collected during microfiltration were characterized using particle size measurements, biochemical and microbiological analysis. The combination of homogenization at 80 MPa and cross-flow microfiltration successfully removed bacteria from skimmed buttermilk: bacterial reduction > 4.8 log10 with 0 cfu/ml in the permeate using the 0.8 μm pore size membrane and 1 cfu/ml with 1.4 μm membrane. Chemical analysis revealed the efficient permeation of proteins, total lipids and polar lipids. Polar lipid classes permeated equally the membrane. This work will contribute in improving the safety of buttermilk-based ingredients.Industrial relevanceThis work describes the development of an innovative process combining homogenization and cross-flow microfiltration for the selective removal of bacteria from industrial buttermilks. This process is an alternative to heat treatments that alter the nutritional and organoleptic properties of food products. The safety of buttermilk-based ingredients containing milk polar lipids of interest will contribute in their economic valorization for human nutrition.