Editing Milk (section)

===Lipids===
{{Main|Butterfat}}
Full fat milk contains about 33 grams of fat per liter, including about 19 grams of saturated fat, 1.2 grams of omega 6 fatty acids, and 0.75 grams of omega 3 fatty acids per liter. The amount of fat varies for products where (some of) the fat has been removed, such as in skimmed milk.<ref>{{Cite journal |last1=Haug |first1=Anna |last2=Høstmark |first2=Arne T. |last3=Harstad |first3=Odd M. |date=2007-09-25 |title=Bovine milk in human nutrition – a review |journal=Lipids in Health and Disease |language=en |volume=6 |issue=1 |pages=25 |doi=10.1186/1476-511X-6-25 |doi-access=free |issn=1476-511X |pmc=2039733 |pmid=17894873}}</ref>

Initially milk fat is secreted in the form of a fat globule surrounded by a [[Milk fat globule membrane|membrane]].<ref name="Fox-1995-v2">Fox, P.F. Advanced Dairy Chemistry: Vol 2 Lipids. 2nd Ed. Chapman and Hall: New York, 1995.</ref> Each fat globule is composed almost entirely of triacylglycerols and is surrounded by a membrane consisting of complex lipids such as [[phospholipid]]s, along with proteins. These act as [[emulsifier]]s which keep the individual globules from coalescing and protect the contents of these globules from various [[enzyme]]s in the fluid portion of the milk. Although 97–98% of lipids are triacylglycerols, small amounts of di- and monoacylglycerols, free cholesterol and cholesterol esters, free fatty acids, and phospholipids are also present. Unlike protein and carbohydrates, fat composition in milk varies widely due to genetic, lactational, and nutritional factor difference between different species.<ref name="Fox-1995-v2" />

Fat globules vary in size from less than 0.2 to about 15 [[micrometre|micrometers]] in diameter between different species. Diameter may also vary between animals within a species and at different times within a milking of a single animal. In unhomogenized cow's milk, the fat globules have an average diameter of two to four micrometers and with homogenization, average around 0.4 micrometers.<ref name="Fox-1995-v2"/> The [[fat-soluble]] vitamins [[vitamin A|A]], [[vitamin D|D]], [[vitamin E|E]], and [[vitamin K|K]] along with essential fatty acids such as linoleic and linolenic acid are found within the milk fat portion of the milk.<ref name="On Food and Cooking"/>

{| class="sortable wikitable" style="margin:auto"
|+Main milk fatty acids, length, share of total<ref name="LubaryHofland2010">{{cite journal |last1=Lubary |first1=Marta |last2=Hofland |first2=Gerard W. |last3=ter Horst |first3=Joop H. |title=The potential of milk fat for the synthesis of valuable derivatives |journal=European Food Research and Technology |volume=232 |issue=1 |year=2010 |pages=1–8 |issn=1438-2377 |doi=10.1007/s00217-010-1387-3 |s2cid=85373338|doi-access=free}}</ref>
|-
! Fatty acid !! length !! mol% (rounded) 
|-
| Butyryl || C4 ||  12 
|-
| Myristyl || C14 || 11 
|-
| Palmityl || C16 || 24 
|-
| Oleyl || C18:1 || 24 
|}