Interaction between whey protein and soy lecithin and its influence on physicochemical properties and in vitro digestibility of emulsion: A consideration for mimicking milk fat globule.

In this study, from the perspective of simulating the milk fat globule (MFG) emulsion, the interaction between soybean lecithin (SL) and the main protein in milk, whey protein (WP), and its effect on physical characteristics and lipid digestion were investigated through multiple spectroscopic techniques and in vitro digestion. The mechanism of SL and WP was static quenching, indicating that a complex formed between WP and SL through hydrophobic interaction and hydrogen bonding. The addition of SL changed the secondary structure of WP. When the ratio of SL to WP was 1:3, the obtained SL-WP emulsion that simulated milk fat globule exhibited the smallest particle size distribution and the highest absolute value of zeta potential. In addition, the emulsion exhibited high encapsulation efficiency (91.67 ± 1.24 %) and good stability. Compared with commercially available infant formula (IF), the final free fatty acid release of prepared SL-WP emulsion was close to that of human milk (HM). The addition of lecithin increased the digestibility of fat and the release of free fatty acids, and the digestive characteristic and particle size change also were closer to that of HM from results of kinetics of free fatty acid release and microstructure analysis.

Profiling of phospholipid classes and molecular species in human milk, bovine milk, and goat milk by UHPLC-Q-TOF-MS.

This study aimed to identify differences of lipidome and fatty acid composition among human, bovine and caprine milk fat globule membrane (MFGM) using a lipidomics approach. In total, 11 lipid classes were determined, including PC, PE, SM, PG, PI, PS, Cer, PA, HexCer, Hex2Cer and CL. Using positive and negative ionization modes, 73 and 156 common significantly differential lipid species were identified in three typical MFGM. The oleic acid (C18:1) was the dominant fatty acid in human (28.29 ± 0.04 g/100 g) and caprine (35.71 ± 0.02 g/100 g) MFGM, whereas Palmitic acid (C16:0, 29.13 ± 0.07 g/100 g) was the dominant fatty acid in bovine MFGM. In addition, there was no significant difference in long chain fatty acids between human MFGM and caprine milk. Overall, the results provide essential insights into differential lipids characterization in MFGM, along with a theoretical basis for the design of new infant formula.

Influence of milk fat globule membrane and milk protein concentrate treated by ultrasound on the structural and emulsifying stability of mimicking human fat emulsions.

The primary objective of the present study was to investigate the effectiveness of ultrasonic treatment time on the particle size, molecular weight, microstructure and solubility of milk fat globule membrane (rich in phospholipid, MPL) and milk protein concentrate (MPC). The mimicking human fat emulsions were prepared using modified proteins and compound vegetable oil and the structural, emulsifying properties and encapsulation efficiency of emulsions were evaluated. After ultrasonic treatment, the cavitation caused particle size decreased and structure change of both MPL and MPC, resulting in the enhancement of protein solubility. While, there was no significant change in molecular weight. Modified proteins by ultrasonic may cause a reduction in particle size and an improvement in emulsifying stability and encapsulation efficiency of emulsions. The optimal ultrasonic time to improve functional properties of MPL emulsion and MPC emulsion were 3 min and 6 min, respectively. The emulsifying stability of MPL emulsion was superior to MPC emulsion, which indicated that MPL is more suitable as membrane material to simulate human fat. Therefore, the obtained results can provide basis for quality control of infant formula.

Comparative Analysis of Lipid Digestion Characteristics in Human, Bovine, and Caprine Milk Based on Simulated In Vitro Infant Gastrointestinal Digestion.

Lipid digestion characteristics in human, bovine, and caprine milk were investigated using an infant in vitro digestion model. Our results suggested that particle size in bovine and caprine milk increased initially and then decreased over time, whereas the particle size in human milk continuously decreased. The lipolysis degree of human milk (86.8%) was higher than that in bovine (80.2%) and caprine (82.7%) milk (P < 0.05). Compared to human milk, bovine and caprine milk released higher unsaturated fatty acids and lower SFAs. In addition, 12 and 84 glyceride species were significantly different between bovine and human milk, during gastrointestinal digestion (P < 0.05). Another 13 and 92 glyceride species were found to be significantly different between caprine and human milk. A total of 30 and 31 lipids were screened as biomarkers to further clarify the differences related to lipid digestion properties of human, bovine, and caprine milk.

Lecithin alleviates protein flocculation and enhances fat digestion in a model of infant formula emulsion.

This study investigates whether lecithin could fasten lipolysis through the alleviation of protein aggregation in an infant formula emulsion model. Our previous study reported low intestinal digestion of infant formula could be due to the aggregation of proteins that slow lipid digestion. The emulsion contained lipids droplets simulating the fatty acid composition in breast milk, different levels of lecithin and milk protein. The interphase proteins were replaced with lecithin in a dose-dependent manner. The results showed the addition of 5% and 7% lecithin improves the physical stability, narrows the range of particle size, reduces the mean particle size and increases the zeta potential. The 5% lecithin emulsion showed the highest rate and extent of lipid and protein digestion. These positive effects were caused by lecithin through stabilizing the emulsion and suppressing droplet flocculation after digestion. Lecithin promotes lipid digestion and may improve the "insufficient fat supply" in infant formula.