Powdered milk, also calledmilk powder,[1]dried milk, ordry milk, is a manufactureddairy product made by evaporating milk todryness. One purpose of drying milk is to preserve it; milk powder has a far longershelf life than liquid milk and does not need to berefrigerated, due to its low moisture content. Another purpose is to reduce its bulk for the economy of transportation. Powdered milk and dairy products include such items as dry whole milk, nonfat (skimmed) dry milk, drybuttermilk, drywhey products and dry dairy blends. Many exported dairy products conform to standards laid out inCodex Alimentarius.
Powdered milk is used for food as an additive, for health (nutrition), and also inbiotechnology[2] (saturating agent).[clarification needed]
WhileMarco Polo wrote ofMongolianTatar troops in the time ofKublai Khan who carried sun-dried skimmed milk as "a kind of paste",[3] the first modern production process for dried milk was invented by the Russian doctor Osip Krichevsky in 1802.[4] The first commercial production of dried milk was organized by the Russian chemist M. Dirchoff in 1832. In 1855, T. S. Grimwade took a patent on a dried milk procedure,[5] though William Newton had patented a vacuum drying process as early as 1837.[6]
In modern times, powdered milk is usually made byspray drying[7] nonfatskimmed milk, whole milk, buttermilk or whey.Pasteurized milk is first concentrated in anevaporator to approximately 50 percent 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.[8]
Alternatively, the milk can be dried bydrum 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 flavour, due tocaramelization caused by greater heat exposure.
Another process isfreeze drying, which preserves many nutrients in milk, compared to drum drying.[9]
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 flavour, and itsbulk density.
Powdered milk is frequently used in the manufacture ofinfant formula, confectionery such as chocolate andcaramel 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 Indian milk balls known asgulab jamun and a popular Indian sweet delicacy (sprinkled with desiccated coconut) known aschum chum (made with skim milk powder). Many no-cook recipes that usenut butters use powdered milk to prevent the nut butter from turning liquid by absorbing the oil.[10]
Powdered milk is also a common item inUN 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). Like other dry foods, it is considered nonperishable and is favored bysurvivalists,hikers, and others requiring nonperishable, easy-to-prepare food.
Because of its resemblance tococaine and other drugs, powdered milk is sometimes used in filmmaking as a non-toxicprop that may beinsufflated.[11]
The weight of nonfat dry milk (NFDM) to use is about 10% of the water weight.[12][note 1] Alternatively, when measuring by volume rather than weight, one cup of fluid milk from powdered milk requires one cup of water and one-third cup of powdered milk.
Milk powders contain all 21 standardamino acids, the building blocks ofproteins, and are high in solublevitamins andminerals.[13] According to USAID,[14] the typical average amounts of major nutrients in the unreconstituted nonfat dry milk are (by weight) 36% protein, 52% carbohydrates (predominantlylactose), calcium 1.3%, potassium 1.8%. Whole milk powder, on the other hand, contains on average 25–27% protein, 36–38% carbohydrates, 26–40% fat, and 5–7% ash (minerals). In Canada, powdered milk must contain addedvitamin D in an amount such that a reasonable daily intake of the milk will provide between 300 and 400International units (IU) of vitamin D.[15] However, inappropriate storage conditions, such as high relative humidity and high ambient temperature, can significantly degrade thenutritive value of milk powder.[16]
Commercial milk powders are reported to containoxysterols (oxidized cholesterol)[17] in higher amounts than in fresh milk (up to 30 μg/g, versus trace amounts in fresh milk).[18]Oxysterols are derivatives of cholesterol that are produced either byfree radicals or by enzymes. Some free radicals-derived oxysterols have been suspected of being initiators ofatherosclerotic plaques.[19] For comparison,powdered eggs contain even more oxysterols, up to 200 μg/g.[18]
As of 2021, the largest producers of milk powder are New Zealand, China, Argentina and Brazil.[20]
European production of milk powder in fiscal year 2019–2020 was estimated at around 3.0 million tonnes of which the main volume was exported in bulk packing or consumer packs.
Australia also has a significant milk powder export industry, exporting over 13,000 tonnes of skim and whole milk powder in fiscal year 2020–2021, to a value of approximately AUD $83 000 000.
Brands on the market includeNido, from the companyNestlé, Incolac from the company Milcobel, Dutch Lady fromFrieslandCampina and Puck fromArla Foods.
Some of the largest businesses in the industry areNestlé,Danone,Lactalis,Fonterra,FrieslandCampina,Dean Foods,Arla Foods,Dairy Farmers of America,Kraft Foods,Saputo, andParmalat.
In the2008 Chinese milk scandal,adulteration withmelamine was found inSanlu-brandinfant formula, added to fool tests into reporting higher protein content. Thousands became ill, and some children died, after consuming the product.[21]
In August 2013, China temporarily suspended all milk powder imports from New Zealand, after a scare wherebotulism-causing bacteria were falsely detected in several batches of New Zealand-producedwhey protein concentrate. As a result of the product recall, theNew Zealand dollar slipped by 0.8% (to 77.78 US cents) based on expected losses in sales from this single commodity.[22]
Fat-free powdered milk is used as a saturating agent toblock nonspecific binding sites on supports likeblotting membranes (nitrocellulose,polyvinylidene fluoride (PVDF) or nylon),[23] preventing binding of further detection reagents and subsequent background.[24] It may be referred asBlotto. The majorprotein of milk,casein, is responsible for most of the binding site saturation effect.
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