Preparation of milk fat globule membrane ingredients enriched in polar lipids: Composition characterization and digestive properties.

In this study, milk fat globule membrane (MFGM) ingredients enriched in polar lipids was prepared using membrane filtration, including microfiltration, diafiltration, and ultrafiltration from butter serum powder. Polar lipids (phospholipids, sterols, and gangliosides) in prepared MFGM ingredients were analyzed by 31P NMR, GC-MS, and UPLC-MS/MS, respectively. The lipolysis degree and microstructure of MFGM ingredient and soybean lecithin-emulsification during in vitro digestion were also analyzed. Microfiltration showed higher concentration efficiency than ultrafiltration which increased 2.16% and 2.73% in phospholipid, respectively. Moreover, diafiltration concentrated more polar lipids (6.39% of phospholipid) than microfiltration. MFGM ingredients had high level of sphingomyelin (1.27-1.36%) and ration of GD3 than GM3 of 9.25-9.88-fold of total gangliosides. The different lipolysis behavior between MFGM ingredient-emulsification and soybean lecithin-emulsification were correlated with their different polar lipid compositions. Phospholipids from both MFGM ingredients and soybean lecithin could help maintain the initial structure during the gastric digestion. These results could provide a scientific basic for developing high-polar lipids food, particularly infant formulas and special functional foods.

Static stability of partially crystalline emulsions: Impacts of carrageenan and its blends with xanthan gum and/or guar gum.

In the present study, four different combinations of gums, including carrageenan (CG), its binary blends with xanthan gum (XG) or guar gum (GG) in equal ratios, and its ternary blends with XG and GG in three equal ratios, were involved into making partially crystalline emulsions (PCEs), respectively. The freshly prepared emulsions were systematically characterized by rheological property, particle size distribution, microscopic morphology, interfacial property, and intermolecular interactions, and their emulsion stabilities were further evaluated using multiple light scattering technique and storage test. All PCEs stabilized by gum blends (CG + XG, CG + GG, and CG + XG + GG) obtained decreased apparent viscosities at 0.01 s-1 (10.12-25.32 Pa·s), particle sizes (3.12-4.06 µm), as well as interfacial protein concentrations (22.60-27.01 mg/m2), which were much lower than those with single CG (35.98 Pa·s, 6.72 µm, and 47.74 mg/m2, respectively). The microscopic morphology showed that blending CG with XG and/or GG contributed to formation of firmer three-dimensional matrix, thereby preventing the aggregation of fat droplets. Inclusion of XG and/or GG also significantly reduced contribution of hydrophobic interactions from 0.72 to 0.24-0.44 mg/mL. Both multiple light scattering and storage test revealed that emulsion instabilities were mainly manifested as a clarification at the bottom and an agglomeration at the top. PCE-CG + XG + GG exhibited superior stability with low creaming index (6.20 %) and viscosity (1180.0 mPa·s) after three months of storage. The research aims to evaluate the effects of CG and its blends with XG and GG on stability of PCEs, and the results potentially provide valuable information for manufacture of stable PCE foods.

O/W Emulsion Stabilized by Bovine Milk Phospholipid-Protein Nanoemulsions: Preparation, Stability, and In Vitro Digestion.

This study aims to prepare a stable oil-in-water (O/W) emulsion with droplets of approximately 3-5 µm and a structured phospholipid (PL)-protein membrane that is similar to human milk fat globules. A nanoemulsion with an average droplet size of 200 nm prepared with bovine milk PL-protein, a milk fat globule membrane (MFGM)-rich ingredient, was used as an emulsifier to form an O/W emulsion with an average droplet size of 3.96 µm. Stable O/W emulsions were formed with a low concentration (1 wt %) of the MFGM-rich ingredient. The nanoemulsion was adsorbed at the oil-water interface. The O/W emulsions stored at 4 °C did not show structural damage upon 7 days of storage. The deformation or partial deformation of nanoemulsion droplets attached to lipid droplets may contribute to the physical stability of the emulsion. In vitro digestion of the O/W emulsion showed a low lipolysis degree in gastric digestion, and the final hydrolysis efficiency of the O/W emulsion was 62.74%, which is higher than that of traditional infant formula.