Powdered milk: Difference between revisions
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Commercial milk powders are reported to contain [[oxysterols]] (oxidized cholesterol)<ref>p 655 in "Advanced Dairy Chemistry: Volume 2 - Lipids" by P.F. Fox and P. McSweeney, Birkhäuser, 2006 |
Commercial milk powders are reported to contain [[oxysterols]] (oxidized cholesterol)<ref>p 655 in "Advanced Dairy Chemistry: Volume 2 - Lipids" by P.F. Fox and P. McSweeney, Birkhäuser, 2006 |
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ISBN 978-0-387-26364-9</ref> in higher amounts than in fresh milk (up to 30μg/g, versus trace amounts in fresh milk).<ref name="Z.E. Sikorski, CRC Press 2004">p 296 in "Toxins in Food" by W.M. Dabrowski and Z.E. Sikorski, CRC Press, 2004, ISBN 978-0-8493-1904-4</ref> |
ISBN 978-0-387-26364-9</ref> in higher amounts than in fresh milk (up to 30μg/g, versus trace amounts in fresh milk).<ref name="Z.E. Sikorski, CRC Press 2004">p 296 in "Toxins in Food" by W.M. Dabrowski and Z.E. Sikorski, CRC Press, 2004, ISBN 978-0-8493-1904-4</ref> |
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Oxysterols |
Oxysterols are derivatives of cholesterol that are produced either by [[free radicals]] or by enzymes. Certain [[free radical]]s-derived [[oxysterol]]s have been suspected of being initiators of [[atherosclerosis|atherosclerotic plaques]].<ref>R.W. Hubbard, Y.Ono and A. Sanchez (1989) ''Prog Food Nutr Sci.'' Vol.13(1) pp 17-44. [http://www.ncbi.nlm.nih.gov/pubmed/2678267?dopt=AbstractPlus]</ref> For comparison, [[powdered eggs]] contain even more oxysterols, up to 200μg/g.<ref name="Z.E. Sikorski, CRC Press 2004"/> |
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===Export Market=== |
===Export Market=== |
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Revision as of 18:51, 23 January 2011
Powdered milk is a manufactured dairy product made by evaporating milk to dryness. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content. Another purpose is to reduce its bulk for economy of transportation. Powdered milk and dairy products include such items as dry whole milk, non-fat dry milk, dry buttermilk, dry whey products and dry dairy blends. Many dairy products exported conform to standards laid out in Codex Alimentarius.
Powdered milk is used for food and health (nutrition), and atypically also in biotechnology (saturating agent).
History and manufacture
While Marco Polo wrote of Mongolian Tatar troops in the time of Kublai Khan carrying sun-dried skimmed milk as "a kind of paste,"[1] the first usable commercial production process for dried milk was invented by the Russian chemist M. Dirchoff in 1832. In 1855, T.S. Grimwade took a patent on a dried milk procedure,[2] though a William Newton had patented a vacuum drying process as early as 1837.[3]
In modern times, powdered milk is usually made by spray drying[4] nonfat skim milk, whole milk, buttermilk or whey. Pasteurized milk is first concentrated in an evaporator to approximately 50% milk solids. The resulting concentrated milk is then sprayed into a heated chamber where the water almost instantly evaporates, leaving fine particles of powdered milk solids.
Alternatively, the milk can be dried by drum drying. Milk is applied as a thin film to the surface of a heated drum, and the dried milk solids are then scraped off. However, powdered milk made this way tends to have a cooked flavor, due to caramelization caused by greater heat exposure.
Another process is freeze drying, which preserves many nutrients in milk, compared to drum drying.
The drying method and the heat treatment of the milk as it is processed alters the properties of the milk powder, such as its solubility in cold water, its flavor, and its bulk density.
Food and health uses
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Powdered milk is frequently used in the manufacture of infant formula, confectionery such as chocolate and caramel candy, and in recipes for baked goods where adding liquid milk would render the product too thin. Powdered milk is also widely used in various sweets such as the famous Indian milk balls known as Rasa-Gulla and popular Indian sweet delicacy (sprinkled with desiccated coconut) known as Chum chum (made with skim milk powder).
Powdered milk is also a common item in UN food aid supplies, fallout shelters, warehouses, and wherever fresh milk is not a viable option. It is widely used in many developing countries because of reduced transport and storage costs (reduced bulk and weight, no refrigerated vehicles). As with other dry foods, it is considered nonperishable, and is favored by survivalists, hikers, and others requiring nonperishable, easy-to-prepare food.
Reconstituting one cup of potable fluid milk from powdered milk requires one cup of potable water and one-third cup of powdered milk.
Nutritional value
Milk powders contain all twenty-one standard amino acids, the building blocks of proteins, and are high in soluble vitamins and minerals.[5] According to USAID[6] the typical average amounts of major nutrients in the unreconstituted milk are (by weight) 36% protein, 52% carbohydrates (predominantly lactose), calcium 1.3%, potassium 1.8%. Their milk powder is fortified with Vitamin A and D, 3000IU and 600IU respectively per 100g. However, such inappropriate storage conditions as high relative humidity and high ambient temperature can significantly degrade the nutritive value of milk powder.[7]
Commercial milk powders are reported to contain oxysterols (oxidized cholesterol)[8] in higher amounts than in fresh milk (up to 30μg/g, versus trace amounts in fresh milk).[9] Oxysterols are derivatives of cholesterol that are produced either by free radicals or by enzymes. Certain free radicals-derived oxysterols have been suspected of being initiators of atherosclerotic plaques.[10] For comparison, powdered eggs contain even more oxysterols, up to 200μg/g.[9]
Export Market
European production of milk powder is estimated around 800.000 tons of which the main volume is exported in bulk packing or consumer packs.
The most popular brands on the market are Nido, from the company Nestlé, Incolac from the company Belgomilk, and Dutch Lady from Friesland-Campina.
Adulteration
In the 2008 Chinese milk scandal, melamine adulterant was found in Sanlu infant formula, added to fool tests into reporting higher protein content. Thousands became ill, and some children died, after consuming the product.
Use in biotechnology
Fat-free powder milk is used as a saturating agent to block non specific binding sites on supports like blotting membranes (Nitrocellulose, PVDF, Nylon),[11] preventing binding of further detection reagents and subsequent background.[12] It may be referred as Blotto. The major protein of milk, casein, is responsible of most of the binding site saturation effect.
See also
References
- ^ p. 262 in "The Book of Ser Marco Polo, Book 1" translated by Sir Henry Yule (3rd edition), Charles Scribner's Sons, New York, 1903
- ^ p 277 in "Condensed Milk and Milk Powder, 3rd edition" authored and published by O.F. Hunziker, 1920
- ^ p 318 in "Foods: Their Composition and Analysis: A Manual for the Use of Analytical Chemists and Others" by A.W. Blyth, published by C. Griffin, 1896
- ^ "Milk Powder" by K.N. Pearce, Food Science Section, New Zealand Dairy Research Institute.[1]
- ^ Milk Powder Nutritional Information, US Dairy Export Council
- ^ USAID Commodities Reference Guide, Non Fat Dry Milk (Jan 2006)
- ^ M. Okamoto and R. Hayashi (1985) "Chemical and Nutritional Changes of Milk Powder Proteins under Various Water Activities" Agric. Biol. Chem., Vol.49 (6), pp 1683-1687.
- ^ p 655 in "Advanced Dairy Chemistry: Volume 2 - Lipids" by P.F. Fox and P. McSweeney, Birkhäuser, 2006 ISBN 978-0-387-26364-9
- ^ a b p 296 in "Toxins in Food" by W.M. Dabrowski and Z.E. Sikorski, CRC Press, 2004, ISBN 978-0-8493-1904-4
- ^ R.W. Hubbard, Y.Ono and A. Sanchez (1989) Prog Food Nutr Sci. Vol.13(1) pp 17-44. [2]
- ^ Technical sheet #768701, from Interchim
- ^ p 82 in "Lab Ref, Volume 2: A Handbook of Recipes, Reagents, and Other Reference Tools for Use at the Bench" by A.S. Mellick and L. Rodgers, CSHL Press, 2002, ISBN 978-0-87969-630-6