Fat globule membranes in ewes' milk: The main enzyme activities during lactation

Martini, Mina; Altomonte, Iolanda; Pesi, Rossana; Tozzi, Maria Grazia; Salari, Federica

doi:10.1016/j.idairyj.2012.07.002

Cited by 12 publications

(17 citation statements)

References 23 publications

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“…The effect of lactation phase was demonstrated mainly when colostrum was compared with mature milk, with enzyme activity in colostrum higher than in mature cow's milk (Shahani et al, 1980;Hadorn et al, 1997;Ontsouka et al, 2003). Similar results were observed for GGT activity between colostrum and the mature milk of sheep (Martini et al, 2013) and mares (Rieland et al, 1998). After the colostral phase, GGT activity was found relatively constant throughout lactation (Martini et al, 2013;Piga et al, 2013).…”

Section: Milk Ggt Activity and Stage Of Lactationsupporting

confidence: 80%

“…Similar results were observed for GGT activity between colostrum and the mature milk of sheep (Martini et al, 2013) and mares (Rieland et al, 1998). After the colostral phase, GGT activity was found relatively constant throughout lactation (Martini et al, 2013;Piga et al, 2013). In the current study, which focused on the lactation stage excluding the colostral phase, a significant effect of DIM was observed.…”

Section: Milk Ggt Activity and Stage Of Lactationsupporting

confidence: 80%

“…In dairy technology, milk GGT activity is used to evaluate the effectiveness of pasteurization since it is completely inactivated by heating at 78°C for 15 s (Fox and Kelly, 2006b). GGT activity in milk varies during lactation and is highest in colostrum compared with mature milk in cows (Hadorn et al, 1997;Ontsouka et al, 2003), ewes (Martini et al, 2013), and mares (Rieland et al, 1998). After the colostral phase, the activity of GGT is considered quite stable, but specific studies on its pattern of change throughout lactation are not available.…”

Section: Calamari 2 L Gobbi F Russo and F Piccioli Cappellimentioning

confidence: 99%

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Pattern of γ-glutamyl transferase activity in cow milk throughout lactation and relationships with metabolic conditions and milk composition1

Calamari

Gobbi

Russo

et al. 2015

Journal of Animal Science

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The main objective of this experiment was to study the γ-glutamyl transferase (GGT) activity in milk during lactation and its relationship with metabolic status of dairy cows, milk yield, milk composition, and cheesemaking properties. The study was performed in a tied stall barn and involved 20 lactations from 12 healthy multiparous Italian Friesian dairy cows. During lactation starting at d 10, milk samples were collected weekly and analyzed for composition, somatic cells count, titratable acidity, and milk coagulation properties. The GGT activity was measured in defatted samples. Blood samples were collected weekly to assess biochemical indicators related to energy, protein, and mineral metabolism, markers of inflammation and some enzyme activities. The lactations of each cow were retrospectively categorized into 2 groups according to their milk GGT activity value through lactation. A median value of GGT activity in the milk of all lactations was calculated (3,045 U/L), and 10 lactations with lower GGT activity were classified as low while 10 lactations with greater GGT activity were classified as high. The average value of milk GGT activity during lactation was 3,863 and 3,024 U/L for high and low, respectively. The GGT activity decreased in early lactation and reached minimum values in the second month (3,289 and 2,355 U/L for high and low, respectively). Thereafter GGT activity increased progressively, reaching values in late lactation of 4,511 and 3,540 U/L in high and low, respectively. On average, milk yield was 40.81 and 42.76 kg/d in high and low, respectively, and a negative partial correlation with milk GGT activity was observed. A greater milk protein concentration was observed in high (3.39%) compared with low (3.18%), and a positive partial correlation with milk GGT activity was observed. Greater titratable acidity in high than that in low (3.75 vs. 3.45 degrees Soxhlet-Henkel/50 mL, respectively) was also observed. Plasma glucose was greater in cows of high than in low group, while plasma urea was lower in the high than in the low group. No relationship between plasma GGT and milk GGT activity was observed. Our results show an important effect of lactation stage on milk GGT activity. The individual effect observed from consecutive lactations and the relationship between milk GGT activity and milk protein concentration in healthy cows could open prospects for GGT as a future tool in improving milk protein content.

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Section: Milk Ggt Activity and Stage Of Lactationsupporting

confidence: 80%

Section: Milk Ggt Activity and Stage Of Lactationsupporting

confidence: 80%

Section: Calamari 2 L Gobbi F Russo and F Piccioli Cappellimentioning

confidence: 99%

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Pattern of γ-glutamyl transferase activity in cow milk throughout lactation and relationships with metabolic conditions and milk composition1

Calamari

Gobbi

Russo

et al. 2015

Journal of Animal Science

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“…Alternatively BTN may mediate the secretion of fat globules by indirectly interacting with XOR, working as a receptor of reactive oxygen species generated by XOR (Jack and Mather, 1990;Oggs et al, 2004). The increased activity of XOR detected when smaller MFGs are secreted (Martini et al, 2013b), may confirm that XOR is involved in the secretion of the globule.…”

Section: Major Proteins Of the Milk Fat Globule Membranementioning

confidence: 73%

“…However, the absence of the oxidase activity of XOR in ewe colostrum (Martini et al, 2013b) suggests that the enzyme is not expressed in early lactation (Liao et al, 2011) or, if present, it probably does not have an antibacterial role, at least in the initial stages of lactation. In fact as is known, the protective role of the newborn is mainly linked to other components, primarily immunoglobulins.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

The Macrostructure of Milk Lipids: The Fat Globules

Martini

Salari

Altomonte

2013

Critical Reviews in Food Science and Nutrition

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The aim of this review article is to summarize the information available related to milk fat globules (MFGs) in order to highlight their contribution to the nutritional and technological characteristics of milk and dairy products. The macrostructure of milk lipids is composed of globules made up of triglycerides with different melting points, enveloped by a biological membrane from the mammary epithelial cell. In milks of different animal species, there are different-sized MFGs, ranging from diameters of less than 0.2 μm to a maximum of 15 μm. The average diameter and the number of globules are affected by endogenous, physiological, and exogenous factors. The size of the globules in turn affects the qualitative characteristics of milk and cheese. In addition, the average diameter of the globules and their surface that is exposed to the digestive system affect fat digestibility in different ways. Finally, the components of the MFG membranes have been shown to take part in the secretion process of globules and to have a beneficial effect on human health. In conclusion, by acting on factors influencing the dimensions of the fat globules and by increasing the content of the milk membrane could help adapt milk production to specific consumer targets and improve milk nutritional properties.

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Role of Differentiated-Size Milk Fat Globules on the Physical Functionality of Dairy-Fat Structured Products

Truong

Bhandari

2020

Dairy Fat Products and Functionality

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Bovine milk fat is one of the most important lipids in the human diet and originally exists as globules dispersed in the milk plasma. The typical size of milk fat globules (MFG) ranges from 0.1 to 15 μm with an average diameter of 4 μm (Walstra, 1995) as illustrated in Fig. 14.1a. The MFG size can be classified into three size fractions, i.e. small (<1 μm), intermediate (1-8 μm) and large (>8 μm) MFG sizes (Michalski, Briard, & Michel, 2001;Walstra & Oortwijn, 1969) with their volume-based percentages of 5%, 80% and 1-2%, respectively. The small size fraction accounts for 80% of the MFG size distribution on the basis of number of globules. Formation of various MFG sizes is governed by processes of assembly, growth and secretion of fat globules in the milk-secreting cells of the mammary gland of mammals (Timmen & Patton, 1988). Generally, MFG origins from the endoplasmic reticulum membranes where tiny intracellular lipid droplets (<0.5 μm) having a triacylglycerol (TAG) core enveloped by a single layer of proteins and polar lipids are generated. These lipid micro-droplets fuse to form bigger droplets, regarded as cytoplasmic lipid droplets, whose droplet-droplet fusion is regulated by specific calcium and protein complexes and fusion-promoting agents, e.g. gangliosides (Valivullah, Bevan, Peat, & Keenan, 1988). The intermediate size MFGs are progressively coated by the plasma membrane when being transported to the apical plasma membrane, resulting in the final tri-layer structure of intact milk fat globule membrane

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Fat globule membranes in ewes' milk: The main enzyme activities during lactation

Cited by 12 publications

References 23 publications

Pattern of γ-glutamyl transferase activity in cow milk throughout lactation and relationships with metabolic conditions and milk composition1

Pattern of γ-glutamyl transferase activity in cow milk throughout lactation and relationships with metabolic conditions and milk composition1

The Macrostructure of Milk Lipids: The Fat Globules

Role of Differentiated-Size Milk Fat Globules on the Physical Functionality of Dairy-Fat Structured Products

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