Malted Milk Powder is a dry mixture of malted barley flour, wheat flour and powdered milk.
The malted barley and wheat flour have water added to them, and are simmered to make them a “mash” (as is made by brewers.) The simmering converts the starches into sugar. The water is then filtered, the solids are discarded, liquid milk is added, then moisture is removed by evaporation. The resulting solids are then ground into a light beige coloured powder, and packaged for shipping.
There are many commercial brands of it including Ovaltine, Carnation Malted Milk Powder, Horlicks, etc.
Eaten on its own, the powder has a somewhat bitter taste. But you can sprinkle it on ice cream, add it to milk shakes and baked goods, sprinkle it on peanut butter and banana sandwiches, etc.
You can also buy the powder chocolate-flavoured.
Malted Milk Powder is not the same as Malted Barley Flour (aka Malt Powder.)
Malted Milk Powder was originally was marketed as a health food for invalids and infants.
The first advertisements touted its medicinal properties:
“Malted milk is undoubtedly the best food in use to-day and has given me entire satisfaction. I now greet cases of cholera infantum with renewed confidence in my ability to save them. I have had four cases since the 15th, and all are now out of danger.’ — Edward S. Coburn, M.D. Troy, N.Y. July 25, 1887.
Malted Milk requires no milk; no cooking; contains no starch; no cane sugar. All druggists.” —Advertisement in: Brooklyn Daily Eagle. Saturday Evening, 6 August 1887. Page 3, col 1.
But even from its early days, the manufacturers also had their eyes on a broader market:
“Some say that Malted Milk will help the Temperance cause wonderfully. It really does furnish a cup at last that cheers but does not inebriate…. A hot cup of Malted Milk for breakfast or for any meal is prepared in less time than it takes to tell the story. Over half a gallon of the best drink known for youth or old age may be had from one fifty cent package of Malted Milk.” — Racine, Wisconsin: The Journal Times. Friday, 28 October 1887. Page 3, col 3 and 4.
It really took off, though, in the 1920s when soda fountains discovered the taste it could add to the drinks they made up. Chocolate malted milks, while thought of by many people as a thing of the 1950s, actually first became a craze in America in the 1920s.
One manufacturer in Wisconsin (the Elgin company, started production in 1894, sold to Borden’s in 1903), called their malted milk “Milkine”. It was a mixture of 50% powdered cow’s milk, 22% malted barley, 22 % flour, 5% beef (something), 1% lime (the chemical) and salt. They recommended that you add water, hot or cold, to make a beverage that would give you just about everything you needed for good nutrition. Borden renamed the product from “Milkine” to Meadow Malted Milk, and removed beef from the ingredients.