دهن الزبد

Butterfat or milkfat is the fatty portion of milk. Milk and cream are often sold according to the amount of butterfat they contain.

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Composition

Structure of a triglyceride containing myristic, palmitic, and oleic acid.

Butterfat is mainly composed of triglycerides. Each triglyceride contains three fatty acids. Butterfat triglycerides contain the following amounts of fatty acids (by mass fraction):[1][2][3]

Fatty acid content of butterfat
Type of fatty acid pct
Lower saturated (at most C12)
  
 11%
Myristic saturated C14
  
 12%
Palmitic saturated C16
  
 31%
Stearic saturated C18
  
 11%
Palmitoleic monounsaturated C16:1
  
 4%
Oleic monounsaturated C18:1
  
 24%
Linoleic polyunsaturated C18:2
  
 3%
Alpha-Linolenic polyunsaturated C18:3
  
 1%
Trans (mainly vaccenic C18:1 trans-11)
  
 3%
black: Saturated; grey: Monounsaturated; green: Polyunsaturated; blue: Trans

Butterfat contains about 3% trans fat, which is slightly less than 0.5 grams per US tablespoon.[3] Trans fats occur naturally in meat and milk from ruminants. The predominant kind of trans fat found in milk is vaccenic fatty acid. Trans fats may be also found in some industrially produced foods, such as shortenings obtained by hydrogenation of vegetable oils. In light of recognized scientific evidence, nutritional authorities consider all trans fats equally harmful for health and recommend that their consumption be reduced to trace amounts.[4][5][6][7][8] However, two Canadian studies have shown that vaccenic acid could be beneficial compared to vegetable shortenings containing trans fats, or a mixture of pork lard and soy fat, by lowering total LDL and triglyceride levels.[9][10][11][12][13] A study by the US Department of Agriculture showed that vaccenic acid raises both HDL and LDL cholesterol, whereas industrial trans fats only raise LDL with no beneficial effect on HDL.[14]

Milk fatty acids, length, and position on glycerol (1, 2, 3) [15]
Fatty acid length mol% (rounded) 1 2 3
Butyryl C4 12 0 0 100
Caproyl C6 5 0 7 93
Caprylyl C8 2 25 12 63
Capryl C10 4 17 27 56
Lauryl C12 4 42 53 5
Myristyl C14 11 29 52 19
Palmityl C16 24 47 45 8
Hexadecenoyl C16:1 3 36 46 18
Stearyl C18 7 49 45 6
Oleyl C18:1 24 42 26 32
Linoleyl C18:2 3 23 47 31


U.S. standards

انظر أيضاً: Fat content of milk § Terms for fat content by country

In the U.S., there are federal standards[16] for butterfat content of dairy products.[17][18][19][20] Many other countries also have standards for minimum fat levels in dairy products. Commercial products generally contain the minimum legal amount of fat with any excess being removed to make cream, a valuable commodity.

See also

المراجع

  1. ^ National Research Council, 1976, online edition Fat Content and Composition of Animal Products, Printing and Publishing Office, National Academy of Science, Washington, D.C., ISBN 0-309-02440-4; p. 203
  2. ^ The quote values vary by 1–3% according to the source: Jost, Rolf (2007). "Milk and Dairy Products". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a16_589.pub3. ISBN 978-3527306732.
  3. ^ أ ب "National Nutrient Database for Standard Reference Release 28". United States Department of Agriculture.[dead link]
  4. ^ EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA) (2010). "Scientific opinion on dietary reference values for fats". EFSA Journal. 8 (3): 1461. doi:10.2903/j.efsa.2010.1461.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ UK Scientific Advisory Committee on Nutrition (2007). "Update on trans fatty acids and health, Position Statement" (PDF). Archived from the original (PDF) on 10 December 2010.
  6. ^ Brouwer IA, Wanders AJ, Katan MB (2010). "Effect of animal and industrial trans fatty acids on HDL and LDL cholesterol levels in humans – a quantitative review". PLOS ONE. 5 (3): e9434. Bibcode:2010PLoSO...5.9434B. doi:10.1371/journal.pone.0009434. PMC 2830458. PMID 20209147. S2CID 983576.
  7. ^ "Trans fat". It's your health. Health Canada. Dec 2007. Archived from the original on 20 April 2012.
  8. ^ "EFSA sets European dietary reference values for nutrient intakes" (Press release). European Food Safety Authority. 26 March 2010.
  9. ^ Trans Fats From Ruminant Animals May Be Beneficial – Health News. redOrbit (8 September 2011). Retrieved 22 January 2013.
  10. ^ Bassett, C. M. C.; Edel, A. L.; Patenaude, A. F.; McCullough, R. S.; Blackwood, D. P.; Chouinard, P. Y.; Paquin, P.; Lamarche, B.; Pierce, G. N. (Jan 2010). "Dietary Vaccenic Acid Has Antiatherogenic Effects in LDLr-/- Mice". The Journal of Nutrition. 140 (1): 18–24. doi:10.3945/jn.109.105163. PMID 19923390.
  11. ^ Wang, Flora & Proctor, Spencer (2 April 2008). "Natural trans fats have health benefits, University of Alberta study shows" (Press release). University of Alberta.
  12. ^ Wang Y, Jacome-Sosa MM, Vine DF, Proctor SD (20 May 2010). "Beneficial effects of vaccenic acid on postprandial lipid metabolism and dyslipidemia: Impact of natural trans-fats to improve CVD risk". Lipid Technology. 22 (5): 103–106. doi:10.1002/lite.201000016.
  13. ^ Bassett C, Edel AL, Patenaude AF, McCullough RS, Blackwood DP, Chouinard PY, Paquin P, Lamarche B, Pierce GN (2010). "Dietary Vaccenic Acid Has Antiatherogenic Effects in LDLr−/− Mice". The Journal of Nutrition. 140 (1): 18–24. doi:10.3945/jn.109.105163. PMID 19923390.
  14. ^ David J. Baer, PhD. US Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Laboratory. New Findings on Dairy Trans Fat and Heart Disease Risk, IDF World Dairy Summit 2010, 8–11 November 2010. Auckland, New Zealand
  15. ^ Lubary, Marta; Hofland, Gerard W.; ter Horst, Joop H. (2010). "The potential of milk fat for the synthesis of valuable derivatives". European Food Research and Technology. 232 (1): 1–8. doi:10.1007/s00217-010-1387-3. ISSN 1438-2377.
  16. ^ United States Department of Agriculture Agricultural Marketing Service
  17. ^ USDA Commercial Item Description: Fluid Milk and Milk Products (2018) Accessed January 29, 2020
  18. ^ USDA Specifications for Cream Cheese, Cream Cheese with other Foods, and Related Products Archived 2012-06-14 at the Wayback Machine (1994).
  19. ^ United States Department of Agriculture Standard for Ice Cream Archived 2012-06-16 at the Wayback Machine (1977).
  20. ^ USDA Commercial Item Description: Cream, Eggnog, Half-and-half, and Sour Cream Archived 2012-06-16 at the Wayback Machine (2002).

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