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Human breast milk (HBM) is the "gold standard" for infant nutrition. When breast milk is insufficient or unavailable, infant milk formula (IMF) can provide a safe and nutritious alternative. However, IMFs differ considerably from HBM in composition and health function. We compared the digestibility and potential health functions of IMF containing low cream (LC-) or high cream (HC-) with pooled HBM. After simulated infant digestion of these samples, the bioavailability of key nutrients and immunomodulatory activities were determined via cell-based in vitro assays. A Caenorhabditis elegans leaky gut model was established to investigate cream effects on gut health. Distinct differences were observed in peptide diversity and sequences released from HC-IMF compared with LC-IMF during simulated digestion (p < 0.05). Higher levels of free fatty acids were absorbed through 21-day differentiated Caco-2/HT-29MTX monolayers from HC-IMF, compared with LC-IMF and HBM (p < 0.05). Furthermore, the immune-modulating properties of HC-IMF appeared to be more similar to HBM than LC-IMF, as observed by comparable secretion of cytokines IL-10 and IL-1β from THP-1 macrophages (p > 0.05). HC-IMF also supported intestinal recovery in C. elegans following distortion versus LC-IMF (p < 0.05). These observations suggest that cream as a lipid source in IMF may provide added nutritional and functional benefits more aligned with HBM. [ABSTRACT FROM AUTHOR]

Simple Summary: The aim of this study was to evaluate the effect of conjugated linoleic acid on the milk fat globule size and the ruminal microbiome of goats. In the present study, we found that dietary conjugated linoleic acid supplementation significantly and dose-dependently decreased the milk fat content and fat globule size in Saanen dairy goats, accompanied by an increase in the proportion of small-sized fat globules. Moreover, the dairy goats occurred in parallel with significant changes in the relative abundance of some ruminal bacterial populations. The milk fat content and fat globule size were correlated with the relative abundance of some bacteria, including members of Firmicutes and Bacteroidetes. Notably, our study was the first to analyze the correlation between the ruminal microbiota and fat globule size. These results constitute the first evidence for explaining the mechanism underlying diet-induced fat globules from the perspective of the ruminal microbiome in dairy goats. The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) on milk fat globule (MFG) size and the ruminal microbiome of goats. Twenty-four mid-lactation Saanen dairy goats weighing 49 ± 4.5 kg (168 ± 27 d in milk, 1.2 ± 0.1 kg milk/d, 2–3 years old) were randomly divided into four groups—a control (CON) group, which was fed a basal diet, and three CLA supplementation groups, in which 30 g CLA (low-dose group, L-CLA), 60 g CLA (medium-dose group, M-CLA), or 90 g CLA (high-dose group, H-CLA) was added to the basal diet daily. The experiment lasted for 21 days, during which time goat milk was collected for composition and MFG size analysis. On day 21 of feeding, ruminal fluid was collected from the CON and H-CLA groups for analysis of the changes in microorganismal abundance. The results showed that CLA supplementation did not affect milk production, milk protein, or lactose content in the dairy goats (p > 0.05), but significantly reduced the milk fat content (p < 0.01) compared with the CON group. The CLA supplementation significantly decreased the D[3,2] and D[4,3] of the MFGs in a dose-dependent manner (p < 0.01). Moreover, dietary CLA inclusion increased the proportion of small-sized MFGs and decreased that of large-sized ones. The results of 16S rRNA gene sequencing showed that CLA-induced milk fat depression in dairy goats was accompanied by significant changes in the relative abundance of ruminal bacterial populations, most of which belonged to the Firmicutes and Bacteroidetes phyla. The relative abundance of Rikenellaceae_RC9_gut_group and Prevolellaceae_UCG-003 in Bacteroidetes and UCG-002, Succiniclasticum, and norank_f__norank_o__Clostridia_vadinBB60_group in Firmicutes was significantly higher in the CON group than in the H-CLA group. In contrast, the relative abundance of norank_f__UCG-011, norank_f_Eubacterium_coprostanoligenes_group, unclassified_f__Lachnospiraceae, and UCG-001 in Firmicutes and norank_f__Muribaculaceae in Bacteroidetes was significantly higher in the H-CLA group than in the CON group. Correlation analysis showed that the milk fat content was negatively correlated with the relative abundance of some bacteria, including members of Firmicutes and Bacteroidetes. Similarly, MFG size (D[3,2] and D[4,3]) was negatively correlated with several members of Firmicutes and Bacteroidetes, including Lachnospiraceae, norank_f__UCG-011, UCG-001, norank_f__Eubacterium_coprostanoligenes_group (Firmicutes), and norank_f__Muribaculaceae (Bacteroidetes), while positively correlated with the relative abundance of some members of Firmicutes and Bacteroidetes, including Mycoplasma, Succiniclasticum, norank_f__norank_o__Clostridia_vadinBB60_group, UCG-002 (Firmicutes), and Rikenellaceae_RC9_gut_group (Bacteroidetes). Overall, our data indicated that CLA treatment affected milk fat content and MFG size in dairy goats, and these effects were correlated with the relative abundance of ruminal bacterial populations. These results provide the first evidence to explain the mechanism underlying diet-induced MFG from the perspective of the ruminal microbiome in dairy goats. [ABSTRACT FROM AUTHOR]

Background: Buttermilk, a significant by-product of the dairy industry, is acknowledged as a beneficial food due to its content of water-soluble vitamins, polar lipids, and milk fat globule membranes. This research is focused on investigating the potential of buttermilk as a substitute in the production of a novel soft cheese type ‘‘camembert’’. Methods: A total of 12 cheese samples of camembert cheese, both with and without buttermilk, were prepared and subjected to a series of physico-chemical analyses in October 2023 to measure protein, fat, total solids, pH, and production yield. Texture Profile Analysis was applied to evaluate textural characteristics, and the microstructure was examined using Scanning Electron Microscopy. A hedonic scale was employed in sensory evaluation to measure taste intensity. Results: The sample containing 90% cow's milk and 10% buttermilk exhibited the most significant (p≤0.05) physico-chemical characteristics as production yield of 45.33%±0.710, protein content of 28.9%±0.58, fat content of 24.88%±0.026, total solids of 54.62±0.23, and a pH of 6.42±0.58. Sensory evaluations demonstrated that camembert samples containing buttermilk were distinguished by high sensory quality and satisfactory taste profiles. In addition, a dense and tightly fused protein matrix was observed in the microstructure of the buttermilk fortified cheese. The results also emphasized that the acidic nature of buttermilk significantly affected the production yield, total solids content, and textural characteristics, evidenced by a hardness of 3.36 N and fracturability of 1.75 N. Conclusion: The results validate the use of buttermilk as an effective alternative in the production of a new type of soft cheese, manifesting improved sensory, structural, and physico-chemical characteristics. This investigation supports the innovative utilization of buttermilk in cheese production, potentially offering a valuable avenue for dairy industry by-products. DOI: 10.18502/jfqhc.11.2.15647

Background: Buttermilk, a significant by-product of the dairy industry, is acknowledged as a beneficial food due to its content of water-soluble vitamins, polar lipids, and milk fat globule membranes. This research is focused on investigating the potential of buttermilk as a substitute in the production of a novel soft cheese type "camembert". Methods: A total of 12 cheese samples of camembert cheese, both with and without buttermilk, were prepared and subjected to a series of physico-chemical analyses in October 2023 to measure protein, fat, total solids, pH, and production yield. Texture Profile Analysis was applied to evaluate textural characteristics, and the microstructure was examined using Scanning Electron Microscopy. A hedonic scale was employed in sensory evaluation to measure taste intensity. Results: The sample containing 90% cow's milk and 10% buttermilk exhibited the most significant (p=0.05) physico-chemical characteristics as production yield of 45.33%±0.710, protein content of 28.9%±0.58, fat content of 24.88%±0.026, total solids of 54.62±0.23, and a pH of 6.42±0.58. Sensory evaluations demonstrated that camembert samples containing buttermilk were distinguished by high sensory quality and satisfactory taste profiles. In addition, a dense and tightly fused protein matrix was observed in the microstructure of the buttermilk fortified cheese. The results also emphasized that the acidic nature of buttermilk significantly affected the production yield, total solids content, and textural characteristics, evidenced by a hardness of 3.36 N and fracturability of 1.75 N. Conclusion: The results validate the use of buttermilk as an effective alternative in the production of a new type of soft cheese, manifesting improved sensory, structural, and physico-chemical characteristics. This investigation supports the innovative utilization of buttermilk in cheese production, potentially offering a valuable avenue for dairy industry by-products. [ABSTRACT FROM AUTHOR]

Goat milk is considered the optimal substitute for human milk and is characterized by variations in the lipid composition of its fat globules across lactation phases. Therefore, the objective of this study was to thoroughly analyze the differences between goat milk during different lactations and human milk, aiming to offer scientific guidance for the production of functional dairy products. Compared with transitional and mature milk, the findings indicated that the total membrane protein content in goat colostrum exhibited greater similarity to that found in human milk. Additionally, goat milk exhibited higher milk fat globule size, as well as a higher total lipid and protein content than human milk. A total of 1461 lipid molecules across 61 subclasses were identified in goat milk and human milk. The contents of glycerides and glycerophospholipids were higher in goat colostrum, whereas sphingolipids and fatty acids were more abundant in human milk. Meanwhile, the compositions of lipid subclasses were inconsistent. There were 584 differentially expressed lipids identified between human and goat milk, including 47 subclasses that were primarily involved in the metabolism of glycerophospholipids, sphingolipids, and triglycerides. In summary, for both the membrane protein and the lipid composition, there were differences between the milk of different goat lactations and human milk. [ABSTRACT FROM AUTHOR]

Human breast milk (HBM) is the “gold standard” for infant nutrition. When breast milk is insufficient or unavailable, infant milk formula (IMF) can provide a safe and nutritious alternative. However, IMFs differ considerably from HBM in composition and health function. We compared the digestibility and potential health functions of IMF containing low cream (LC-) or high cream (HC-) with pooled HBM. After simulated infant digestion of these samples, the bioavailability of key nutrients and immunomodulatory activities were determined via cell-based in vitro assays. A Caenorhabditis elegans leaky gut model was established to investigate cream effects on gut health. Distinct differences were observed in peptide diversity and sequences released from HC-IMF compared with LC-IMF during simulated digestion (p < 0.05). Higher levels of free fatty acids were absorbed through 21-day differentiated Caco-2/HT-29MTX monolayers from HC-IMF, compared with LC-IMF and HBM (p < 0.05). Furthermore, the immune-modulating properties of HC-IMF appeared to be more similar to HBM than LC-IMF, as observed by comparable secretion of cytokines IL-10 and IL-1β from THP-1 macrophages (p > 0.05). HC-IMF also supported intestinal recovery in C. elegans following distortion versus LC-IMF (p < 0.05). These observations suggest that cream as a lipid source in IMF may provide added nutritional and functional benefits more aligned with HBM.

The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) on milk fat globule (MFG) size and the ruminal microbiome of goats. Twenty-four mid-lactation Saanen dairy goats weighing 49 ± 4.5 kg (168 ± 27 d in milk, 1.2 ± 0.1 kg milk/d, 2–3 years old) were randomly divided into four groups—a control (CON) group, which was fed a basal diet, and three CLA supplementation groups, in which 30 g CLA (low-dose group, L-CLA), 60 g CLA (medium-dose group, M-CLA), or 90 g CLA (high-dose group, H-CLA) was added to the basal diet daily. The experiment lasted for 21 days, during which time goat milk was collected for composition and MFG size analysis. On day 21 of feeding, ruminal fluid was collected from the CON and H-CLA groups for analysis of the changes in microorganismal abundance. The results showed that CLA supplementation did not affect milk production, milk protein, or lactose content in the dairy goats (p > 0.05), but significantly reduced the milk fat content (p < 0.01) compared with the CON group. The CLA supplementation significantly decreased the D[3,2] and D[4,3] of the MFGs in a dose-dependent manner (p < 0.01). Moreover, dietary CLA inclusion increased the proportion of small-sized MFGs and decreased that of large-sized ones. The results of 16S rRNA gene sequencing showed that CLA-induced milk fat depression in dairy goats was accompanied by significant changes in the relative abundance of ruminal bacterial populations, most of which belonged to the Firmicutes and Bacteroidetes phyla. The relative abundance of Rikenellaceae_RC9_gut_group and Prevolellaceae_UCG-003 in Bacteroidetes and UCG-002, Succiniclasticum, and norank_f__norank_o__Clostridia_vadinBB60_group in Firmicutes was significantly higher in the CON group than in the H-CLA group. In contrast, the relative abundance of norank_f__UCG-011, norank_f_Eubacterium_coprostanoligenes_group, unclassified_f__Lachnospiraceae, and UCG-001 in Firmicutes and norank_f__Muribaculaceae in Bacteroidetes was significantly higher in the H-CLA group than in the CON group. Correlation analysis showed that the milk fat content was negatively correlated with the relative abundance of some bacteria, including members of Firmicutes and Bacteroidetes. Similarly, MFG size (D[3,2] and D[4,3]) was negatively correlated with several members of Firmicutes and Bacteroidetes, including Lachnospiraceae, norank_f__UCG-011, UCG-001, norank_f__Eubacterium_coprostanoligenes_group (Firmicutes), and norank_f__Muribaculaceae (Bacteroidetes), while positively correlated with the relative abundance of some members of Firmicutes and Bacteroidetes, including Mycoplasma, Succiniclasticum, norank_f__norank_o__Clostridia_vadinBB60_group, UCG-002 (Firmicutes), and Rikenellaceae_RC9_gut_group (Bacteroidetes). Overall, our data indicated that CLA treatment affected milk fat content and MFG size in dairy goats, and these effects were correlated with the relative abundance of ruminal bacterial populations. These results provide the first evidence to explain the mechanism underlying diet-induced MFG from the perspective of the ruminal microbiome in dairy goats.

Goat milk is considered the optimal substitute for human milk and is characterized by variations in the lipid composition of its fat globules across lactation phases. Therefore, the objective of this study was to thoroughly analyze the differences between goat milk during different lactations and human milk, aiming to offer scientific guidance for the production of functional dairy products. Compared with transitional and mature milk, the findings indicated that the total membrane protein content in goat colostrum exhibited greater similarity to that found in human milk. Additionally, goat milk exhibited higher milk fat globule size, as well as a higher total lipid and protein content than human milk. A total of 1461 lipid molecules across 61 subclasses were identified in goat milk and human milk. The contents of glycerides and glycerophospholipids were higher in goat colostrum, whereas sphingolipids and fatty acids were more abundant in human milk. Meanwhile, the compositions of lipid subclasses were inconsistent. There were 584 differentially expressed lipids identified between human and goat milk, including 47 subclasses that were primarily involved in the metabolism of glycerophospholipids, sphingolipids, and triglycerides. In summary, for both the membrane protein and the lipid composition, there were differences between the milk of different goat lactations and human milk.

Milk fat globules (MFGs) surround the triacylglycerol core that composes milk fat. The aim of this study is to induce milk fat depression via dietary conjugated linoleic acid (CLA) supplementation to study MFG size parameters, number and glycerophospholipid composition. Eighteen Holstein dairy cows (136 ± 28 days in milk, 571 ± 37.9 kg body weight, 27.6 ± 2.1 kg milk/day) were selected and randomly assigned to a control or CLA group for a 14‐day period. Cows were fed a basal diet (control, n = 8) or the control plus 400 g/day CLA (C18:2 cis‐9, trans‐11 38.1% and C18:2 trans‐10, cis‐12 36.8%) (n = 10) for 7 days after which the CLA group was switched to the basal diet for another 7 days along with the control group. Cow performance, milk composition, MFG size and numbers were measured daily. On the seventh day after the start of the experiment, milk samples were identified and the quantification of glycerophospholipid compounds, and RNA were isolated from milk fat samples for a real‐time polymerase chain reaction. Compared with control, at Day 7 from the start of feeding, supplemental CLA did not affect milk production (28.09 vs. 28.50 kg/day), dry matter intake (14.9 vs. 15.4 kg/day), or milk protein (3.55/100 vs. 3.70 g/100 ml) and lactose contents (5.11/100 vs. 5.17 g/100 ml). However, although the specific surface area of MFG (2138 vs. 1815 m²/kg) was greater, CLA reduced milk fat content (1.95/100 vs 3.64 g/100 ml on Day 7) and particle size parameters of MFG. The number of MFG gradually decreased until Day 7 of feeding, and then increased by Day 14 (2.96 × 109 on Day 1, 1.63 × 109 on Day 7 and 2.28 × 109 on Day 14) in the CLA group. Compared with control, glycerophospholipid analysis revealed that concentrations of phosphatidylcholine (PC) (e.g., PC [16:0/18:1] 20322 vs. 29793 nmol/L), lysophosphatidylethanolamine (LPE) (e.g., LPE [18:1] 956 vs. 4610 nmol/L) and phosphatidylethanolamine (PE) (e.g., PE [16:0/18:1] 7000 vs. 9769 nmol/L) in milk lipids decreased during CLA feeding. In contrast, concentrations of phosphatidylinositol (PI) (e.g., PI [18:0/18:1] 4052 vs. 1799 nmol/L) and phosphatidylserine (PS) (e.g., PS [18:1/18:2] 9500 vs. 6843 nmol/L) increased. The messenger RNA abundance of fatty acid synthase, diacylglycerol O‐acyltransferase 1, glycerol‐3‐phosphate acyltransferase 4 and phosphate cytidylyltransferase 1, choline, alpha (PCYT1A) were downregulated in the CLA group, confirming published data demonstrating a negative effect of CLA on lipogenesis in the mammary gland. Overall, these results provided evidence for the important role of lipogenic gene expression in the regulation of MFG size, number and glycerophospholipid composition. [ABSTRACT FROM AUTHOR]

BACKGROUND: Characterising the regulation of milk component synthesis in response to macronutrient supply is critical for understanding the implications of nutritional interventions on milk production. Gene expression in mammary gland secretory cells was measured using RNA isolated from milk fat globules from 6 Holstein-Friesian cows receiving 5-d abomasal infusions of saline, essential amino acids (AA), or glucose (GG) or palm olein (LG) without (LAA) or with (HAA) essential AA, according to a 6 × 6 Latin square design. RNA was isolated from milk fat samples collected on d 5 of infusion and subjected to real-time quantitative PCR. We hypothesised that mRNA expression of genes involved in de novo milk fatty acid (FA) synthesis would be differently affected by GG and LG, and that expression of genes regulating transfer of tricarboxylic acid cycle intermediates would increase at the HAA level. We also hypothesised that the HAA level would affect genes regulating endoplasmic reticulum (ER) homeostasis but would not affect genes related to the mechanistic target of rapamycin complex 1 (mTORC1) or the integrated stress response (ISR) network. RESULTS: Infusion of GG did not affect de novo milk FA yield but decreased expression of FA synthase (FASN). Infusion of LG decreased de novo FA yield and tended to decrease expression of acetyl-CoA carboxylase 1 (ACC1). The HAA level increased both de novo FA yield and expression of ACC1, and tended to decrease expression of mitochondrial phosphoenolpyruvate carboxykinase (PCK2). mRNA expression of mTORC1 signaling participants was not affected by GG, LG, or AA level. Expression of the ε subunit of the ISR constituent eukaryotic translation initiation factor 2B (EIF2B5) tended to increase at the HAA level, but only in the presence of LG. X-box binding protein 1 (XBP1) mRNA was activated in response to LG and the HAA level. CONCLUSIONS: Results show that expression of genes involved in de novo FA synthesis responded to glucogenic, lipogenic, and aminogenic substrates, whereas genes regulating intermediate flux through the tricarboxylic acid cycle were not majorly affected. Results also suggest that after 5 d of AA supplementation, milk protein synthesis is supported by enhanced ER biogenesis instead of signaling through the mTORC1 or ISR networks.

ABSTRACT: Milk fat globule membrane (MFGM) proteins surround the triacylglycerol core comprising milk fat globules (MFG). We previously detected a decrease in the size of fat globules during conjugated linoleic acid (CLA)-induced milk fat depression (MFD), and other studies have reported that some MFGM proteins play a central role in regulating mammary cellular lipid droplet size. However, little is known about the relationship between MFD, MFG size, and MFGM proteins in bovine milk. The aim of this study was to investigate the profile of MFGM proteins during MFD induced by CLA. Sixteen mid-lactating Holstein cows (145 ± 24 d in milk) with similar body condition and parity were divided into control and CLA groups over a 10-d period. Cows were fed a basal diet (control, n = 8) or control plus 15 g/kg of dry matter (DM) CLA (n = 8) to induce MFD. Cow performance, milk composition, and MFG size were measured daily. On d 10, MFGM proteins were extracted and identified by quantitative proteomic analysis, and western blotting was used to verify a subset of the identified MFGM proteins. Compared with controls, supplemental CLA did not affect milk production, DM intake, or milk protein and lactose contents. However, CLA reduced milk fat content (3.73 g/100 mL vs. 2.47 g/100 mL) and the size parameters volume-related diameter D[4,3] (3.72 μm vs. 3.35 μm) and surface area-related diameter D[3,2] (3.13 μm vs. 2.80 μm), but increased specific surface area of MFG (1,905 m2/kg vs. 2,188 m2/kg). In total, 177 differentially expressed proteins were detected in milk from cows with CLA-induced MFD, 60 of which were upregulated and 117 downregulated. Correlation analysis showed that MFG size was negatively correlated with various proteins, including XDH and FABP3, and positively correlated with MFG-E8, RAB19, and APOA1. The results provide evidence for an important role of MFGM proteins in regulating MFG diameter, and they facilitate a mechanistic understanding of diet-induced MFD.

The inevitable role of infant formula as a nutritional alternative to breast milk has led to a search for better ways to improve formulations. One of the most important components of human milk, the milk fat globule, contain 98% triacylglycerides with evolutionally tailored fatty acids and esterification profile delivering up to 50% of the energy intake for infants. A known problem with infant formulation is the low concentration of sn-2 palmitate compared to human milk, leading to low fatty acid absorption and gastrointestinal problems. Microalgae has been recently suggested as an alternative source of lipids for infant formulations to produce a similar fatty acid profile and esterification pattern found in human milk. This review discusses the potential use of microalgal oils enriched in sn-2 palmitate within recombined fat globules in infant formula. Microalgae are a promising source of lipids to replace palm olein in infant formula. Recent studies have shown that the fatty acid profile of microalgal TAGs isolated from specific species can be similar to human milk fat. Research in cultivation, downstream processing, and assessments of costs, food safety, and environmental impacts are now needed to assess the potential of this source to become a commercial reality. [Display omitted] • Palm oil-based infant formula contains palmitic acid esterified at the sn -1,3 position. • Current sources of sn -2 palmitate are expensive and may lead to deforestation. • Microalgal oil is a promising source to replace palm olein in infant formula. [ABSTRACT FROM AUTHOR]

Mammary lipid secretion is generally held to be unique and remarkably uniform between the many different orders of mammals. It produces a unit membrane-bounded milk fat globule (MFG). The unit membrane is separated from the lipoprotein boundary of what was the cytoplasmic lipid droplet (CLD) boundary by a uniform layer of cytoplasmic proteins. In 3–8% of the MFG in all species examined this cytoplasmic layer widens to include cytoplasmic organelles which are referred to as 'crescents'. This defines the MFG secretion as apocrine indicating a closely regulated process which minimises the loss of mammary epithelial cell (MEC) cytoplasm. The apocrine nature of the secretion might be expected since the evolution of the mammary gland is considered to be from an apocrine secreting skin gland. This short Research Reflection review is designed to investigate the exact cytoplasmic interactions which allow such efficient lipid secretion. There are two main scenarios: one which assumes that the observed close association between CLD and GV results in the CLD being released as a consequence of sequential exocytosis of the content of the associated GV. The second assumes that the CLD and the MEC apical plasmalemma interact in some way which causes the CLD to rise out of the cytoplasm enveloped in the plasmalemma. Here I present the evidence for the two possibilities. The first scenario is favoured, but the second cannot be ruled out. [ABSTRACT FROM AUTHOR]

Milk fat globules (MFGs) are secreted from the mammalian gland and are composed of a triacylglycerol core surrounded by a triple membrane structure, the milk fat globule membrane (MFGM). The MFGM contains complex lipids and proteins reported to have nutritional, immunological, neurological and digestive functions. Human and ruminant milk are shown to share a similar MFG structure but with different size, profile and abundance of protein and polar lipids. This review summarizes the reported data on human, bovine, caprine and ovine MFG composition and concentration of bioactive components in different MFG-size fractions. A comprehensive understanding of compositional variations between milk from different species and MFG size fractions may help promote various milk sources as targeted supplements to improve human development and health. MFG size and MFGM composition are species-specific and affected by lactation, diet and breed (or maternal origin). Purification and enrichment methods for some bioactive proteins and lipids present in the MFGM have yet to be established or are not scaled sufficiently to be used to supplement human diets. To overcome this problem, MFG size selection through fractionation or herd selection may provide a convenient way to pre-enrich the MFG fraction with specific protein and lipid components to fulfill human dietary and health requirements. [ABSTRACT FROM AUTHOR]

Lipid droplet size and interfacial coating (protein or phospholipid) varies in early life nutrition and can impact gastrointestinal lipid handling, thereby affecting the rate at which free fatty acids and monoacylglycerides become potentially available for absorption (bioaccessible). We compared gastrointestinal handling and lipid bioaccessibility rates of infant formulas that varied in size and coating and human milk (HM). Infant dynamic digestion was simulated using tinyTIM with advanced gastric compartment. Gastrointestinal handling (lipid top layer formation, emptied lipid rates, bioaccessible lipid rates and enteroendocrine cholecystokinin secretions by Caco-2 cells) of standard IF (sIF), standard IF with added MFGM (sIFM) and concept IF (cIF, Nuturis®) with large, MFGM coated lipid droplets and HM were compared. HM and cIF, both with large lipid droplets, formed an intragastric lipid top layer early during digestion, leading to delayed HM lipid gastric emptying compared to sIF. Gastric aggregate formation preceded lipid top layer formation for sIF, while sIFM remained homogeneous. sIF bioaccessible lipids elicited increased cholecystokinin secretion compared to HM and cIF. Both HM and cIF exhibited lower bioaccessible lipid rates than sIF, suggesting that lipolysis was slower with large lipid droplets. The addition of non-coating MFGM to the standard IF did not significantly impact gastrointestinal handling nor bioaccessibility rates. Gastrointestinal handling of cIF is different from sIF, resulting in a lower lipid bioaccessibility rate, which is closer to that of HM. A lower lipid bioaccessibility rate in early life may promote lipid oxidation over storage, benefiting metabolism, growth, and brain development. [Display omitted] • Standard infant formula contains small protein coated lipid droplets that differ from human milk. • Concept infant formula and human milk have large phospholipid coated lipid droplets. • Large lipid droplets form a lipid top layer that delays gastric lipid emptying. • Enteric lipolysis rate and cholecystokinin response are lower with large droplets. • The lipid bioaccessibility rate of Concept Infant formula is closer to human milk. [ABSTRACT FROM AUTHOR]

Human milk is uniquely optimized for the needs of the developing infant. Its composition is complex and dynamic, driven primarily by maternal genetics, and to a lesser extent by diet and environment. One important component that is gaining attention is the milk fat globule (MFG). The MFG is composed of a triglyceride-rich core surrounded by a tri-layer membrane, also known as the milk fat globule membrane (MFGM) that originates from mammary gland epithelia. The MFGM is enriched with glycerophospholipids, sphingolipids, cholesterol, and proteins, some of which are glycosylated, and are known to exert numerous biological roles. Mounting evidence suggests that the structure of the MFG and bioactive components of the MFGM may benefit the infant by aiding in the structural and functional maturation of the gut through the provision of essential nutrients and/or regulating various cellular events during infant growth and immune education. Further, antimicrobial peptides and surface carbohydrate moieties surrounding the MFG might have a pivotal role in shaping gut microbial populations, which in turn may promote protection against immune and inflammatory diseases early in life. This review seeks to: (1) understand the components of the MFG, as well as maternal factors including genetic and lifestyle factors that influence its characteristics; (2) examine the potential role of this milk component on the intestinal immune system; and (3) delineate the mechanistic roles of the MFG in infant intestinal maturation and establishment of the microbiota in the alimentary canal.

Milk fat globule membrane (MFGM) proteins surround the triacylglycerol core comprising milk fat globules (MFG). We previously detected a decrease in the size of fat globules during conjugated linoleic acid (CLA)-induced milk fat depression (MFD), and other studies have reported that some MFGM proteins play a central role in regulating mammary cellular lipid droplet size. However, little is known about the relationship between MFD, MFG size, and MFGM proteins in bovine milk. The aim of this study was to investigate the profile of MFGM proteins during MFD induced by CLA. Sixteen mid-lactating Holstein cows (145 ± 24 d in milk) with similar body condition and parity were divided into control and CLA groups over a 10-d period. Cows were fed a basal diet (control, n = 8) or control plus 15 g/kg of dry matter (DM) CLA (n = 8) to induce MFD. Cow performance, milk composition, and MFG size were measured daily. On d 10, MFGM proteins were extracted and identified by quantitative proteomic analysis, and western blotting was used to verify a subset of the identified MFGM proteins. Compared with controls, supplemental CLA did not affect milk production, DM intake, or milk protein and lactose contents. However, CLA reduced milk fat content (3.73 g/100 mL vs. 2.47 g/100 mL) and the size parameters volume-related diameter D [4,3] (3.72 μm vs. 3.35 μm) and surface area-related diameter D [3,2] (3.13 μm vs. 2.80 μm), but increased specific surface area of MFG (1,905 m2/kg vs. 2,188 m2/kg). In total, 177 differentially expressed proteins were detected in milk from cows with CLA-induced MFD, 60 of which were upregulated and 117 downregulated. Correlation analysis showed that MFG size was negatively correlated with various proteins, including XDH and FABP3, and positively correlated with MFG-E8, RAB19, and APOA1. The results provide evidence for an important role of MFGM proteins in regulating MFG diameter, and they facilitate a mechanistic understanding of diet-induced MFD. [ABSTRACT FROM AUTHOR]

Research data on milk composition in cetaceans are scattered and fragmentary. This paper analyses the gross and mineral composition, the fatty acids profile and the fat globule size of bottlenose dolphin (Tursiops truncatus) colostrum and milk at early lactation. The milk samplings were carried out on three lactating female of bottlenose dolphins at the 1st, 4-5 and 20- 42 day post partum. High percentages of dry matter (51.88%), fat (26.08%) and protein (13.83%) were found in the colostrum on the first day, while there was a tendency for these components to decrease in the milk. The average diameter the milk fat globule (7.07 μm) of this species was assessed for the first time. The milk was rich in unsaturated fatty acids, which were more than twice compared to the saturated fatty acids (unsaturated / saturated ratio = 2.6). The main fatty acids of dolphin milk were C16: 0, C16:1 n-7, C18: 1n-9, C20: 1 n-11 C20: 5 and C22:6n-3. Several FA tended to increase from colostrum to milk: C12: 0 doubled, C20: 1 n-7 and C22:1 n-11 tripled, C20: 1 n-9 quintupled in later milk samples. Differently, other FA tended to decrease: C18: 3 n-3 was approximately 4 times lower and C24: 0 and C24: 1 halved in milk compared to colostrum. In conclusion, this paper contributes to the knowledge of the nutritional value of milk from bottlenose dolphins maintained under human care. Higher content of nutritional components such as fat and protein was found in the first day colostrum compared to milk. Moreover, the findings of this study highlight abundance of unsaturated fatty acids and large sized milk fat globules in dolphin milk. [ABSTRACT FROM AUTHOR]

Bovine milk fat globule membrane (MFGM) proteins are crucial to calf health and human nutrition, but a knowledge gap exists for its lactation stage-specific variations in cows and buffaloes. This study employed mass spectrometry to identify the inter- and intra-lactation stage-specific MFGM proteins in Murrah buffalo (Mu) and Holstein Friesian cow (HF). Mu exhibited higher proteins (n = 264) than HF (n = 250); utilizing multivariate analysis, differentially abundant proteins (n = 78 in HF, n = 31 in Mu) were identified specific to lactation stages. The MFGM proteins were categorized into health-associated (47.1%), lipid-associated proteins (44.1%), and shared proteins (8.8%). HF milk contained all health-associated proteins detected in Mu, besides possessing unique proteins (e.g., BTN1A1, SAA3, and ENPP3), including lipid-associated proteins that contributed to improved calf immunity. These results suggest HF milk is more suitable for calf health and dairy product development, including expanding our understanding of lactation stage-specific MFGM proteins and highlighting their potential health benefits. [Display omitted] • Multivariate analysis in HF and Mu clearly distinguished lactation stages. • Proteins for calf development (e.g., LPL, FOLR1) peaked in first lactation stage. • Immunity imparting MFGM proteins like BTN1A1, SAA3, and ENPP3 were found in HF. • Both HF and Mu contained essential amino acid providers like CSN1S2 and LTF proteins. • Proteins related to smaller fat globules (such as LSS) showed higher abundance in HF. [ABSTRACT FROM AUTHOR]

Milk lipids are organized in the form of milk fat globules (MFG), ranging in size from 0. 1 to 15 μm. The MFG size is closely associated with the composition of fatty acids, polar lipids, sphingolipids, cholesterol and the content of the MFG membrane (MFGM). Also, the MFGM integral proteins and glycoconjugates differ in composition and structure between different MFG size groups. These compositional differences may modulate the functionality of the MFG and its interaction with microbial cells. We report that small (2.3 μm) MFG facilitates the growth of the Gram-positive bacterium Bacillus subtilis whereas induction of biofilm formation was found in the presence of large (7.0 μm) MFG. Attempting to distinguish between the role played by the size from that played by the composition of the MFG, we compared phospholipid composition between treatments. We found that adjusting the phosphatidylethanolamine (PE) level to the concentration found in the small MFG, increased growth but suppressed biofilm formation in the presence of large MFG. The same normalization protocol for phosphatidylinositol (PI) or sphingomyeline (SM) did not exert a similar effect, suggesting a specific role for PE in regulating bacteria proliferation. We suggest that the content of MFGM, affected by MFG size, governs the ability of B. subtilis to utilize lipids from milk fat. This process might affect the bacterial decision-making toward biofilm formation or growth.

Dairy powders enriched with milk fat globules (MFGs) and milk fat globule membrane (MFGM) materials are gaining interest in food industry due to their bioactive benefits, including the promotion of brain development and cognitive functions, as well as improvements in gut health and immunity. MFGs/MFGM ingredients have been incorporated into infant formula (IF) to bridge the nutritional gap between formula and breast milk. The structure and composition of MFGs/MFGM ingredients significantly influence their functionalities and physiological properties. This review provides an update on recent research concerning the factors influencing the structure, composition, and functionalities of MFGs/MFGM ingredients, including the species, lactation stage and feeding methods. Additionally, conventional separation methods are discussed versus novel membrane filtration techniques. The main part of this review covers the recent progress and trends arising from the influence of the industrial dairy produce units, including thermal treatment and low temperature storage, homogenization, and non-thermal processes. Variability in reports on the structure and composition of MFGs/MFGM across studies poses challenges in discerning whether these differences arise from varied processing techniques or analytical methods. Establishing standard analytical methods remains an ongoing research topic. By-products such as cheese whey or buttermilk continue to serve as primary raw materials for the preparation of MFGs/MFGM ingredients in the industry. Studies on the preparation of MFGs/MFGM materials while maintaining their natural state are relatively limited. Further research into the structural and compositional changes of MFGs/MFGM during food processes is essential, as it has the potential to provide the key information on their physiological properties and tech-functionalities. • The structure and composition of MFGs/MFGM exhibit variability across studies. • Recent updates have been made on the identification of the structure and composition of MFGs/MFGM. • Summarizing the techno-functionalities changes during the conventional and emerging industrial dairy processing methods. [ABSTRACT FROM AUTHOR]

Lipid digestion characteristics of a novel milk formula with large phospholipid-coated lipid droplets named Nuturis® (NF), four current standard formulas (CF1-4), and freshly expressed human milk (HM) were evaluated using a dynamic in vitro model of infant gastrointestinal digestion. Lipolysis degree (LD), triacylglycerol (TAG) lipolysis products including diacylglycerols, monoacylglycerols, and free fatty acids were determined. Structural changes including particle size distribution and microstructure of milk digesta were analyzed and compared. The LD of NF and HM showed no significant difference at 120 min of both gastric (G120) and intestinal digestion (I120). Compared to CFs, the lipolysis of NF was slower during gastric digestion while it caught up during the intestinal phase in which most of the lipolysis occurred. Milk lipolysis products are highly related to the milks initial TAG composition. Regarding structural changes during digestion, NF is closer to HM than CFs. In the gastric phase, NF and HM had constant particle size (∼5 μm) with mostly intact lipid droplet structures, while CFs started with smaller particles but flocculated to larger droplet aggregates (8–10 μm). Once the chyme had moved into the intestinal phase, the emulsion of all milks coalesced into large aggregates. This study showed that lipid digestion and structural changes of milk emulsions during digestion are highly dependent on the characteristics of the lipid droplets. In contrast to current standard formulas with small lipid droplets, milk formula with large phospholipid-coated lipid droplets and HM showed similar LD at the end of gastrointestinal digestion and droplet aggregation behaviors during digestion. [Display omitted] • Lipolysis and structural changes of milks were evaluated by dynamic in vitro infant digestion model. • The lipid products of milk are highly associate to their triacylglycerol composition. • Lipid globules structure of milk affect gastric digestion emulsion structure. • The gastric pre-structuring of milk may influence infant intestinal lipid release pattern. [ABSTRACT FROM AUTHOR]

There has been a growing interest in understanding how the relative levels of human milk fat globule (MFG) components change over the course of lactation, how they differ between populations, and implications of these changes for the health of the infant. In this article, we describe studies published over the last 30 years which have investigated components of the MFG in term milk, focusing on changes over the course of lactation and highlighting infant and maternal factors that may influence these changes. We then consider how the potential health benefits of some of the milk fat globule membrane (MFGM) components and derived ingredients relate to compositional and functional aspects and how these change throughout lactation. The results show that the concentrations of phospholipids, gangliosides, cholesterol, fatty acids and proteins vary throughout lactation, and such changes are likely to reflect the changing requirements of the growing infant. There is a lack of consistent trends for changes in phospholipids and gangliosides across lactation which may reflect different methodological approaches. Other factors such as maternal diet and geographical location have been shown to influence human MFGM composition. The majority of research on the health benefits of MFGM have been conducted using MFGM ingredients derived from bovine milk, and using animal models which have clearly demonstrated the role of the MFGM in supporting cognitive and immune health of infants at different stages of growth and development.

Abstract Background Milk lipids originate from cytoplasmic lipid droplets (LD) that are synthesized and secreted from mammary epithelial cells by a unique membrane-envelopment process. Butyrophilin 1A1 (BTN1A1) is one of the membrane proteins that surrounds LD, but its role in bovine mammary lipid droplet synthesis and secretion is not well known. Methods The objective was to knockout BTN1A1 in bovine mammary epithelial cells (BMEC) via the CRISPR/Cas9 system and evaluate LD formation, abundance of lipogenic enzymes, and content of cell membrane phospholipid (PL) species. Average LD diameter was determined via Oil Red O staining, and profiling of cell membrane phospholipid species via liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results Lentivirus-mediated infection of the Cas9/sgRNA expression vector into BMEC resulted in production of a homozygous clone BTN1A1 (−/−) . The LD size and content decreased following BTN1A1 gene knockout. The mRNA abundance of fatty acid synthase (FASN) and peroxisome proliferator-activated receptor-gamma (PPARG) was downregulated in the BTN1A1 (−/−) clone. Subcellular analyses indicated that BTN1A1 and LD were co-localized in the cytoplasm. BTN1A1 gene knockout increased the percentage of phosphatidylethanolamine (PE) and decreased phosphatidylcholine (PC), which resulted in a lower PC/PE ratio. Conclusions Results suggest that BTN1A1 plays an important role in regulating LD synthesis via a mechanism involving membrane phospholipid composition.

Abstract Background Characterising the regulation of milk component synthesis in response to macronutrient supply is critical for understanding the implications of nutritional interventions on milk production. Gene expression in mammary gland secretory cells was measured using RNA isolated from milk fat globules from 6 Holstein-Friesian cows receiving 5-d abomasal infusions of saline, essential amino acids (AA), or glucose (GG) or palm olein (LG) without (LAA) or with (HAA) essential AA, according to a 6 × 6 Latin square design. RNA was isolated from milk fat samples collected on d 5 of infusion and subjected to real-time quantitative PCR. We hypothesised that mRNA expression of genes involved in de novo milk fatty acid (FA) synthesis would be differently affected by GG and LG, and that expression of genes regulating transfer of tricarboxylic acid cycle intermediates would increase at the HAA level. We also hypothesised that the HAA level would affect genes regulating endoplasmic reticulum (ER) homeostasis but would not affect genes related to the mechanistic target of rapamycin complex 1 (mTORC1) or the integrated stress response (ISR) network. Results Infusion of GG did not affect de novo milk FA yield but decreased expression of FA synthase (FASN). Infusion of LG decreased de novo FA yield and tended to decrease expression of acetyl-CoA carboxylase 1 (ACC1). The HAA level increased both de novo FA yield and expression of ACC1, and tended to decrease expression of mitochondrial phosphoenolpyruvate carboxykinase (PCK2). mRNA expression of mTORC1 signaling participants was not affected by GG, LG, or AA level. Expression of the ε subunit of the ISR constituent eukaryotic translation initiation factor 2B (EIF2B5) tended to increase at the HAA level, but only in the presence of LG. X-box binding protein 1 (XBP1) mRNA was activated in response to LG and the HAA level. Conclusions Results show that expression of genes involved in de novo FA synthesis responded to glucogenic, lipogenic, and aminogenic substrates, whereas genes regulating intermediate flux through the tricarboxylic acid cycle were not majorly affected. Results also suggest that after 5 d of AA supplementation, milk protein synthesis is supported by enhanced ER biogenesis instead of signaling through the mTORC1 or ISR networks.

The phospholipid (PL) composition and milk fat globule (MFG) structure are important for MFG membrane function. However, the effects of various processing methods on these factors remain unclear. In the present study, we compared the effects of different processing methods for infant formula (IF) production on PLs and MFGs. Homogenization and heat sterilization significantly decreased the number of PL species in raw milk (RM, 104). Heat sterilization and spray drying significantly reduced PL content in RM (160.3 ± 12.2 mg/L; p < 0.05). During processing, the average volume diameter (5.67 ± 0.81 μm) and zeta potential (−7.37 ± 0.27 mV) of RM were significantly reduced (p < 0.05). After homogenization, PLs were distributed in a circular and dotted manner around the MFGs. After spray drying, PL fluorescent rings lost structural integrity. Therefore, the tested processing methods substantially damaged the PL composition and MFG structure. These results may provide a scientific basis for future IF development. • Homogenization, heat sterilization, and spray drying for infant formula were studied. • HTST better maintained the phospholipid species number of RM than UHT. • During processing, the zeta potential of raw milk was significantly reduced. • Phospholipids on milk globule membranes were labeled with a fluorescent probe. • The structure of the milk globule membrane loses integrity after processing. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of dietary soybean lecithin (SL) on immune function and milk quality in lactating sows. The dietary treatments included a control group and three groups that replace soybean oil with 1%, 2% and 3% SL respectively in the diets. The weight of piglets at weaning and the average daily gain (ADG) were increased by supplementation of 3% SL (P

Consumers are demanding more natural, healthy, and high-quality products. The addition of health-promoting substances, such as bioactive compounds, to foods can boost their therapeutic effect. However, the incorporation of bioactive substances into food products involves several technological challenges. They may have low solubility in water or poor stability in the food environment and/or during digestion, resulting in a loss of their therapeutic properties. Over recent years, the encapsulation of bioactive compounds into laboratory-engineered colloidal structures has been successful in overcoming some of these hurdles. However, several nature-assembled colloidal structures could be employed for this purpose and may offer many advantages over laboratory-engineered colloidal structures. For example, the casein micelles and milk fat globules from milk and the oil bodies from seeds were designed by nature to deliver biological material or for storage purposes. These biological functional properties make them good candidates for the encapsulation of bioactive compounds to aid in their addition into foods. This review discusses the structure and biological function of different nature-assembled carriers, preparation/isolation methods, some of the advantages and challenges in their use as bioactive compound delivery systems, and their behavior during digestion.

Abstract Background Xanthosine treatment has been previously reported to increase mammary stem cell population and milk production in cattle and goats. However, the underlying molecular mechanisms associated with the increase in stem cell population and milk production remain unclear. Methods Primiparous Beetal goats were assigned to the study. Five days post-partum, one mammary gland of each goat was infused with xanthosine (TRT) twice daily (2×) for 3 days consecutively, and the other gland served as a control (CON). Milk samples from the TRT and CON glands were collected on the 10th day after the last xanthosine infusion and the total RNA was isolated from milk fat globules (MEGs). Total RNA in MFGs was mainly derived from the milk epithelial cells (MECs) as evidenced by expression of milk synthesis genes. Significant differentially expressed genes (DEGs) were subjected to Gene Ontology (GO) terms using PANTHER and gene networks were generated using STRING db. Results Preliminary analysis indicated that each individual goat responded to xanthosine treatment differently, with this trend being correlated with specific DEGs within the same animal’s mammary gland. Several pathways are impacted by these DEGs, including cell communication, cell proliferation and anti-microbials. Conclusions This study provides valuable insights into transcriptomic changes in milk producing epithelial cells in response to xanthosine treatment. Further characterization of DEGs identified in this study is likely to delineate the molecular mechanisms of increased milk production and stem or progenitor cell population by the xanthosine treatment.

Lipid digestion is critical for infant development, and yet, the interconnection between lipid digestion and the microbiota is largely understudied. This review focuses on digestion of the human milk fat globule and summarizes the current understanding of the mechanisms underlying this process in infants. We first discuss the partial hydrolysis of milk fat in the stomach, which leads to rearrangement of lipid droplets, creating a lipid-water interface necessary for duodenal lipolysis. In the first few months of life, secretion of pancreatic triglyceride lipase, phospholipase A 2 , and bile salts is immature. The dominant lipases aiding fat digestion in the newborn small intestine are therefore pancreatic lipase-related protein 2 and bile salt–stimulated lipase from both the exocrine pancreas and milk. We summarize the interaction between ionic fatty acids and cations to form insoluble fatty acid soaps and how it is influenced by various factors, including cation availability, pH, and bile salt concentration, as well as saturation and chain length of fatty acids. We further argue that the formation of the soap complex does not contribute to lipid bioavailability. Next, the possible roles that the gut microbiota plays in lipid digestion and absorption are discussed. Finally, we provide a perspective on how the manufacturing process of infant formula and dairy products may alter the physical properties and structure of lipid droplets, thereby altering the rate of lipolysis. [ABSTRACT FROM AUTHOR]

Background: Milk lipids originate from cytoplasmic lipid droplets (LD) that are synthesized and secreted from mammary epithelial cells by a unique membrane-envelopment process. Butyrophilin 1A1 (BTN1A1) is one of the membrane proteins that surrounds LD, but its role in bovine mammary lipid droplet synthesis and secretion is not well known. Methods: The objective was to knockout BTN1A1 in bovine mammary epithelial cells (BMEC) via the CRISPR/Cas9 system and evaluate LD formation, abundance of lipogenic enzymes, and content of cell membrane phospholipid (PL) species. Average LD diameter was determined via Oil Red O staining, and profiling of cell membrane phospholipid species via liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: Lentivirus-mediated infection of the Cas9/sgRNA expression vector into BMEC resulted in production of a homozygous clone BTN1A1(−/−). The LD size and content decreased following BTN1A1 gene knockout. The mRNA abundance of fatty acid synthase (FASN) and peroxisome proliferator-activated receptor-gamma (PPARG) was downregulated in the BTN1A1(−/−) clone. Subcellular analyses indicated that BTN1A1 and LD were co-localized in the cytoplasm. BTN1A1 gene knockout increased the percentage of phosphatidylethanolamine (PE) and decreased phosphatidylcholine (PC), which resulted in a lower PC/PE ratio. Conclusions: Results suggest that BTN1A1 plays an important role in regulating LD synthesis via a mechanism involving membrane phospholipid composition. [ABSTRACT FROM AUTHOR]

Background: Characterising the regulation of milk component synthesis in response to macronutrient supply is critical for understanding the implications of nutritional interventions on milk production. Gene expression in mammary gland secretory cells was measured using RNA isolated from milk fat globules from 6 Holstein-Friesian cows receiving 5-d abomasal infusions of saline, essential amino acids (AA), or glucose (GG) or palm olein (LG) without (LAA) or with (HAA) essential AA, according to a 6 × 6 Latin square design. RNA was isolated from milk fat samples collected on d 5 of infusion and subjected to real-time quantitative PCR. We hypothesised that mRNA expression of genes involved in de novo milk fatty acid (FA) synthesis would be differently affected by GG and LG, and that expression of genes regulating transfer of tricarboxylic acid cycle intermediates would increase at the HAA level. We also hypothesised that the HAA level would affect genes regulating endoplasmic reticulum (ER) homeostasis but would not affect genes related to the mechanistic target of rapamycin complex 1 (mTORC1) or the integrated stress response (ISR) network. Results: Infusion of GG did not affect de novo milk FA yield but decreased expression of FA synthase (FASN). Infusion of LG decreased de novo FA yield and tended to decrease expression of acetyl-CoA carboxylase 1 (ACC1). The HAA level increased both de novo FA yield and expression of ACC1, and tended to decrease expression of mitochondrial phosphoenolpyruvate carboxykinase (PCK2). mRNA expression of mTORC1 signaling participants was not affected by GG, LG, or AA level. Expression of the ε subunit of the ISR constituent eukaryotic translation initiation factor 2B (EIF2B5) tended to increase at the HAA level, but only in the presence of LG. X-box binding protein 1 (XBP1) mRNA was activated in response to LG and the HAA level. Conclusions: Results show that expression of genes involved in de novo FA synthesis responded to glucogenic, lipogenic, and aminogenic substrates, whereas genes regulating intermediate flux through the tricarboxylic acid cycle were not majorly affected. Results also suggest that after 5 d of AA supplementation, milk protein synthesis is supported by enhanced ER biogenesis instead of signaling through the mTORC1 or ISR networks. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of dietary soybean lecithin (SL) on immune function and milk quality in lactating sows. The dietary treatments included a control group and three groups that replace soybean oil with 1%, 2% and 3% SL respectively in the diets. The weight of piglets at weaning and the average daily gain (ADG) were increased by supplementation of 3% SL (P < 0.05). The content of phisphatidylcholine in milk was increased by supplementation of 2% and 3% SL (P < 0.05), and the average diameter of milk fat globule was decreased by supplementation of 1%, 2% and 3% SL (P < 0.05). The immunoglobulin levels of milk and plasma were enhanced when 2% or 3% SL was added (P < 0.05). Collectively, dietary SL decreased the milk fat globule size and improved the content of phospholipid in milk, as well as enhanced the immunoglobulin levels in milk and plasma of sows and piglets. [ABSTRACT FROM AUTHOR]

This study aims to prepare infant formula concentrates (IFs) simulating human milk fat globule (HMFG) composition, size and distribution. Mixed plant oil (21.3% palm oil, 2.8% flaxseed oil, 2.6% soybean oil, 29.9% rapeseed oil and 43.4% corn oil) and concentrated whey protein were applied to mimic triacylglycerols and phospholipids in HMFG respectively. IF1-IF6 were produced by different homogenization pressures or physically mixed with different proportions. IF4, prepared with 95% IF1 (4.29 μm), 1% IF2 (0.497 μm) and 4% IF3 (9.43 μm), showed a mean particle size of 3.96 μm and 49.77% milk fat globule membrane protein, and had the closest size distribution and interface with HMFG. The prepared IFs showed good stability with the Turbiscan stability index (IF6 (1.75)

[Display omitted] • Fat composition and structure of infant formulae and human milk is analyzed. • Main method and characteristics of simulated human milk fat are reviewed. • The fat composition and structure have an impact on fat digestion and metabolism. • Limitations and future developments of simulated human milk fat were discussed. Differences in the composition and structure of lipid droplets in infant formula (IF) and human milk (HM) can affect the fat digestion of infants, leading to high risk of metabolic diseases during later stages of growth. Recently, interest in simulating HM fat (HMF) has gradually increased due to its beneficial functions for infants. Much research focuses on the simulation of fatty acids and triacylglycerols. Enzymatic combined with new technologies such as carbodiimide coupling immobilization enzymes, solvent-free synthesis, and microbial fermentation can improve the yield of simulated HMF. Furthermore, fat modification in next-generation IF requires attention to the impact on the structure and function of milk fat globules (MFG). This review also summarizes the latest reports on MFG structure simulation, mainly related to the addition method and sequence of membrane components, and other milk processing steps. Although some of the simulated HMF technologies and products have been applied to currently commercially available IF, the cost is still high. Furthermore, understanding the fat decomposition of simulated HMF during digestion and assessing its nutritional effects on infants later in life is also a huge challenge. New process development and more clinical studies are needed to construct and evaluate simulated HMF in the future. [ABSTRACT FROM AUTHOR]

Many studies have shown that milk fat globule (MFG) diameter varies in dairy cows in relation to diet and/or breed. However, the mechanisms governing the size of the fat globules remain hypothetical. Our objective was to determine the variable biochemical characteristics (fat, protein, fatty acids (FA), casein and calcium (Ca) contents) between individual milk which differed in both MFG diameter and membrane content, in order to speculate about the links between milk synthesis and MFG secretion. With this aim, we built five databases of individual milk samples from 21 experiments performed between 2003 and 2011. Three of them grouped data from trials dealing with breed/diet effects and included information about: (i) MFG size/membrane, fat and protein contents (n=982), (ii) previous parameters plus FA profile (n=529) and (iii) previous parameters plus true protein composition and calcium contents (n=101). A hierarchical clustering analysis performed on these three databases yielded four groups differing in the MFG characteristics. We observed significant differences among groups for the following parameters: (i) fat content and fat : protein ratio; (ii) de novo and polyunsaturated FA contents; (iii) Ca contents. These relationships could result from potential process regulating the synthesis and secretion of MFG: (i) the apical membrane turnover for MFG secretion and (ii) cytoplasmic lipid droplet formation in the lactocyte during its migration from the basal to the apical pole. The two other databases grouped data from trials dealing with milking frequency (n=211), milking kinetics and milk type (residual v. cisternal) (n=224). They were used to study the relationships between the size of the MFG and milk composition for high native fat contents (from 60 up to 100 g/kg in residual milks). We observed curvilinear relationships between the size of the MFG and fat content, as well as with the fat : protein ratio. This result suggests that MFG diameter reaches a threshold but mechanisms are still unknown.

We examined the effects of 2 grass silage-based diets differing in forage:concentrate (FC) ratio and those of a red clover silage-based diet on intake, milk production, ruminal fatty acid (FA) biohydrogenation, milk FA composition, and milk fat globule (MFG) size distribution. Ten multiparous Nordic Red cows received the following treatments: grass silage-based diets containing high (70:30, HG) or low (30:70, LG) FC ratio or a red clover silage-based diet with an FC ratio of 50:50 (RC) on a dry matter basis. Determinations of MFG were performed from fresh milk samples without addition of EDTA so the results of fat globules >1 µm in diameter are emphasized instead of the entire globule population. Lower FC ratio in grass silage-based diets increased milk production with no effect on daily fat yield, leading to 13% lower milk fat concentration. The effect of FC ratio on MFG size was moderate. It did not affect the volume-weighted diameter in grass silage-based diets, although LG lowered the volume-surface diameter of MFG in the size class >1 µm compared with HG. Compared with HG, feeding LG moderately decreased the biohydrogenation of 18:2n-6, leading to a higher level of polyunsaturated fatty acids in milk fat. Feeding RC lowered milk fat concentration and daily milk fat yield compared with grass silage-based diets. The volume-weighted diameter of MFG in the size class >1 µm was smaller in RC milk compared with grass silage-based diets. Feeding RC increased the flow of 18:3n-3 at the omasum by 2.4-fold and decreased the apparent ruminal 18:3n-3 biohydrogenation compared with grass silage-based diets despite similar intake of 18:3n-3. It also resulted in the lowest amount of saturated FA and the highest amounts of cis -9 18:1, 18:3n-3, and polyunsaturated FA in milk. In conclusion, LG decreased milk fat content and induced minor changes in MFG size distribution compared with HG, whereas RC lowered milk fat production, altered milk FA composition to nutritionally more beneficial direction, and led to smaller MFG compared with grass silage-based diets. [ABSTRACT FROM AUTHOR]

Abstract Ultrasonic homogenization of full fat milk is known to provide changes in the acid-induced gelation behavior, in terms of acceleration of gel formation and increased gel strength. In this study, the dependency of this behavior on ultrasonic power level and treatment temperature was illustrated using an ultrasonic flow cell system, which minimizes temperature increase during treatment. Gel formation was studied by acidification with glucone-δ-lactone at 30 °C using small deformation rheology and effects of ultrasonication on whey protein denaturation, milk fat globule size distribution and proteins associated with the milk fat globule membrane were evaluated. Results illustrate how increased acid-gel strength upon ultrasonication, partly, was attributed to denaturation of whey proteins, but also indicate that changes in the milk fat globule membrane, in terms of increased association of caseins with the milk fat globule membrane, can be of importance by facilitating the formation of highly functional milk fat globule/protein complexes. Highlights • Ultrasound treatment of milk changes the acid-induced gelation behavior. • Temperature and power level was shown to be of importance. • Effects was linked to denaturation and shift in milk fat globule membrane proteins. [ABSTRACT FROM AUTHOR]

The fat globules in milk are unique oil droplets that are stabilized by a specific and structurally complex membrane, the milk fat globule membrane (MFGM). In the last decade, excellent progress has been made on studying the structure of the milk fat globules and the MFGM and how common processing treatments affect these structures to deliver dairy products with improved functional properties. Although the digestion of milk fat to deliver energy and lipid-soluble nutrients is essential for survival of the neonate, there is little understanding of the complex processes involved. The structural alterations to fat globules during gastrointestinal processing affect the way in which milk fat is digested, absorbed, and metabolized. The packaging of these globules within the MFGM or in other forms may affect the bioaccessibility of raw or processed milk fat globules; in turn, this may affect access of the gastrointestinal enzymes to the globules and, therefore, may influence the rate and extent of lipid digestion. This review focuses on recent advances in understanding milk fat globules during gastrointestinal digestion, including the effects of processing on their bioavailability and the kinetics of lipid digestion. Possible effects of the dairy matrix on lipid digestion and physiological responses are briefly described. [ABSTRACT FROM AUTHOR]

Milk fat globule (MFG) size ranges over 3 orders of magnitude, from less than 200 nm to over 15 μm. The significance of MFG size derives from its tight association with its lipidome and proteome. More specifically, small MFG have relatively higher content of membrane compared with large globules, and this membrane exerts diverse positive health effects, as reported in human and animal studies. In addition, MFG size has industrial significance, as it affects the physicochemical and sensory characteristics of dairy products. Studies on the size regulation of MFG are scarce, mainly because various confounders indirectly affect MFG size. Because MFG size is determined before and during its secretion from mammary epithelial cells, studies on the size regulation of its precursors, the intracellular lipid droplets (LD), have been used as a proxy for understanding the mechanisms controlling MFG size. In this review, we provide evidence for 2 distinct mechanisms regulating LD size in mammary epithelial cells: co-regulation of fat content and triglyceride-synthesis capacity of the cells, and fusion between LD. The latter is controlled by the membrane's polar lipid composition and involves mitochondrial enzymes. Accordingly, this review also discusses MFG size regulation in the in vivo metabolic context, as MFG morphometric features are often modulated under conditions that involve animals' altered energy status. [ABSTRACT FROM AUTHOR]

• B. subtilis postbiotics composition was modulated by MFG substrate size. • Energy-production cycle metabolites of bacteria grown on small MFG were elevated. • Metabolites that are used by the bacteria for biofilm formation were decreased when large MFG were used as a substrate. • Moderated response to LPS in MEC was documented when cells treated with small MFG postbiotics. Milk lipids are secreted into the milk collecting ducts as milk fat globule (MFG) where they are exposed to microflora of the udder. We hypothesized that MFG size modulates the metabolic fingerprint of B. subtilis. Accordingly, small and large (2.3 and 7.0 µm, respectively) MFG were isolated from cow milk and used as a substrate for B. subtilis. Small MFG enhanced growth, whereas large MFG enhanced biofilm formation. Bacteria incubated with small MFG had increased concentration of metabolites related to energy production whereas metabolome of the bacteria incubated with large MFG had reduced concentrations of metabolites important for biofilm formation. Postbiotics from bacteria grown on large MFG exacerbated the proinflammatory response of MEC to LPS, and changed the expression of key enzymes involved in lipid and protein synthesis. Our results suggest that MFG size modulate growth trajectories and metabolome of B. subtilis , and consequently the stress response of host cells. [ABSTRACT FROM AUTHOR]

Human breast milk is the optimal source of nutrition for infant growth and development. Breast milk fats and their downstream derivatives of fatty acids and fatty acid-derived terminal mediators not only provide an energy source but also are important regulators of development, immune function, and metabolism. The composition of the lipids and fatty acids determines the nutritional and physicochemical properties of human milk fat. Essential fatty acids, including long-chain polyunsaturated fatty acids (LCPUFAs) and specialized pro-resolving mediators, are critical for growth, organogenesis, and regulation of inflammation. Combined data including in vitro, in vivo, and human cohort studies support the beneficial effects of human breast milk in intestinal development and in reducing the risk of intestinal injury. Human milk has been shown to reduce the occurrence of necrotizing enterocolitis (NEC), a common gastrointestinal disease in preterm infants. Preterm infants fed human breast milk are less likely to develop NEC compared to preterm infants receiving infant formula. Intestinal development and its physiological functions are highly adaptive to changes in nutritional status influencing the susceptibility towards intestinal injury in response to pathological challenges. In this review, we focus on lipids and fatty acids present in breast milk and their impact on neonatal gut development and the risk of disease.

Human milk is uniquely optimized for the needs of the developing infant. Its composition is complex and dynamic, driven primarily by maternal genetics, and to a lesser extent by diet and environment. One important component that is gaining attention is the milk fat globule (MFG). The MFG is composed of a triglyceride-rich core surrounded by a tri-layer membrane, also known as the milk fat globule membrane (MFGM) that originates from mammary gland epithelia. The MFGM is enriched with glycerophospholipids, sphingolipids, cholesterol, and proteins, some of which are glycosylated, and are known to exert numerous biological roles. Mounting evidence suggests that the structure of the MFG and bioactive components of the MFGM may benefit the infant by aiding in the structural and functional maturation of the gut through the provision of essential nutrients and/or regulating various cellular events during infant growth and immune education. Further, antimicrobial peptides and surface carbohydrate moieties surrounding the MFG might have a pivotal role in shaping gut microbial populations, which in turn may promote protection against immune and inflammatory diseases early in life. This review seeks to: (1) understand the components of the MFG, as well as maternal factors including genetic and lifestyle factors that influence its characteristics; (2) examine the potential role of this milk component on the intestinal immune system; and (3) delineate the mechanistic roles of the MFG in infant intestinal maturation and establishment of the microbiota in the alimentary canal.

MicroRNAs are small gene-regulatory RNAs that are found in various biological fluids, including milk, where they are often contained inside extracellular vesicles (EVs), like exosomes. In a previous study, we reported that commercial dairy cow’s milk microRNAs resisted simulated digestion and were not exclusively associated with canonical exosomes. Here, we report the characterization of a milk EV subset that sediments at lower ultracentrifugation speeds and that contains the bulk of microRNAs. Milk EVs were isolated by differential ultracentrifugation and Iodixanol density gradient (IDG), and analysed for (1) microRNA enrichment by reverse transcription and quantitative polymerase chain reaction (RT-qPCR), and (2) EV-associated proteins by Western blot. Milk EVs were characterized further by dynamic light scattering (DLS), density measurements, fluorescent DiR and RNA labelling, high-sensitivity flow cytometry (HS-FCM), transmission electron microscopy (TEM), proteinase K and RNase A assay, and liquid chromatography tandem-mass spectrometry (LC-MS/MS). We found that the bulk of milk microRNAs (e.g., bta-miR-125b, bta-miR-148a, etc.) sediment at 12,000 g and 35,000 g. Their distribution pattern was different from that of exosome-enriched proteins, but similar to that of several proteins commonly found in milk fat globule membranes (MFGM), including xanthine dehydrogenase (XDH). These low-speed ultracentrifugation pellets contained cytoplasm-enclosing phospholipid bilayered membrane vesicles of a density comprised between 1.11 and 1.14 g/mL in Iodixanol. This milk EV subset of ~100 nm in diameter/~200 nm hydrodynamic size resisted to proteinase K digestion and protected their microRNA content from RNase A digestion. Our results support the existence of a milk EV subset pelleting at low ultracentrifugations speeds, with a protein coating comparable with MFGM, which contains and protects the bulk of milk microRNAs from degradation. This milk EV subset may represent a new EV population of interest, whose content in microRNAs and proteins supports its potential bioactivity.