In the food realm, the word “scald” can mean a cooking technique, or a disease that hits fruit.
In cooking, it means to heat a liquid to a point where it’s just about to reach the boiling point. At this point, small bubbles will start to appear around the edges. There should also be steam starting. You remove the liquid from the heat before the scald turns into a boil. It can be done in a saucepan or in a microwave.
In cooking the term is typically used in reference to milk.
The skin that forms on top of scalded milk is protein which has coagulated as moisture has left it.
For fruit, see: Scald (fruit)
Scalding milk for bread
Many people speculate as to why many older recipes for bread — and some new ones — direct you to scald the milk first. The recipes do not give any reason why.
Some people speculate that scalding was necessary in the days when milk was unpasteurized, to make it safe. Others speculate that it was to bring the milk up to a certain temperature for benefit of the yeast or the recipe (though they can’t explain why you’re supposed to raise the temperature way up and then let it cool right back down.) Some say that it was an old wives’ tale, and that they never bothered scalding milk ever. Some say that they’ll willing to believe heating the milk was necessary for some reason or other at one point in time, but that it’s probably not now because all milk has been heated during pasteurization. Other say that they don’t understand why they’re being told to do it, but that they follow orders and do it.
Howard Hillman, travel and food journalist, writes:
“Scalding has two primary purposes: to kill pathogenic microorganisms and to destroy certain enzymes that would keep emulsifying agents in the milk from doing their thickening job. Since those two goals are accomplished when milk is pasteurized at the dairy, scalding need only be done when you use raw (unpasteurized) milk. Many cookbook writers do not know this fact and therefore direct their readers to scald the milk even though it is usually unnecessary today.” [1]Hillman, Howard. The New Kitchen Science: A Guide to Knowing the Hows and Whys for Fun and Success in the Kitchen. Houghton Mifflin Company. Boston: 2003. Page 102.
Harold McGee, food science writer, feels that scalding milk has a utility beyond food safety:
“Both fresh and powdered milk are sometimes included in doughs for their flavor and nutritiousness, but they can weaken the gluten of bread dough and produce a dense loaf. The culprit appears to be a whey protein, which can be inactivated by scalding the milk-bringing it just to the boil-before use. (The milk must be cooled before mixing to avoid precooking the flour and damaging the yeast.)” [2]McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner. 2004. Kindle Edition. p. 545.
Food scientist Zoe Ann Holmes (Emeritus Professor, Nutrition and Food Management, Oregon State University) concurs that there is an element in milk that can weaken gluten. At the time that she wrote (2006), food scientists weren’t sure what it was, but suspected it was a protein in the milk that acts somewhat as a protease. Heating the milk to 92 C (198 F) inactivates that element. If left active, the bread will be coarser and less risen than one made with scalded milk. [3]Holmes, ZoeAnn. Why does one scald milk for bread production? In “Food Resource 1996-2006.” Corvallis, Oregon: Oregon State University. Retrieved 4 July 2006 from http://food.oregonstate.edu/faq/bread/bread12.html.
What consumer-purchased milk would have reached the 92 C (198 F) temperature?
Not powdered milk. Powdered milk is now made by spraying droplets of milk through air which has been heated to 200 to 220 C (392 to 428 F) onto a roller — but the droplets of milk don’t come close to reaching the temperature of the air because the heat energy is used up during their brief fling through the air in evaporating the water from the milk. Though, the King Arthur Flour company of Norwich, Vermont sells (as of 2023) a special “Baker’s Special Dry Milk” (powdered milk): its “high-heat processing disables protease, an enzyme that normally slows down yeast growth.” [Note the concern stated here is for yeast growth as opposed to gluten development.]
HTST pasteurized milk is treated in a temperature range between 71 to 74 C (160 to 165 F).
It’s only UHT pasteurized milk, treated at 137 C (280 F), that is heated above the 92 C (198 F) temperature that Holmes specifies. But, it’s only held at that temperature for about 2 seconds. It’s not certain if that’s enough for it to qualify as scalded. (Besides, UHT milk is very hard to find — the process is normally applied only to cream.)
Holmes adds, “…regardless of the milk, if you don’t know it has been adequately heated, scald it.”
When making bread with scalded milk, the milk should be cooled to about 43 to 46 C (110 to 115 F) before yeast is added. Cooks used to test the temperature with a few drops of the milk on their wrist. Now, affordable instant read thermometers negate the necessity of guesswork.
Scalding milk for custards
Cooks are often advised for scald milk for pumpkin pies, and for custards in general. The intent seems to be, as Hillman puts it, “to destroy certain enzymes that would keep emulsifying agents in the milk from doing their thickening job” (though he disagrees that it’s still necessary.)
Scalding milk for yoghurt
Some yoghurt experts advise you to scald milk because even pasteurized milk can contain some bacteria that might compete with the bacterial culture you are introducing to make yoghurt. A scald temperature kills the bacteria that pasteurization missed.
Scalding milk for ice cream
There’s a mysterious scalding suggestion by Sarah Tyson Rorer, founder of the Philadelphia Cooking School circa 1883: “To make good ice cream, it is first necessary to have a good quality of cream. Scald half the cream to prevent excessive swelling.” [4]Sarah Tyson Rorer. Mrs Rorer’s New Cook Book. Philadelphia: Arnold And Company. 1903 edition. Page 600.
To scald or not to scald
All that being said, many home cooks now maintain that they ignore scalding directions, and life in the kitchen has gone on without the ceiling falling in. You can probably keep on doing what you are doing, scalding or not scalding, until more science is found on this issue one way or another, and depending on how precisely you are aiming to control your results in the kitchen.
Language Notes
Blanching fruits and vegetables can be done by steam, or by immersing in boiling water for a brief period of time. In some instances, the world “scald” has been used to refer to the water immersion process. Fannie Farmer made such a distinction in her book, The Boston Cooking-School Cook Book:
“In steaming, the product is heated by steam but is not immersed in water. In scalding, the product is plunged into the water. The minutes are counted from the time it is immersed without waiting for the water to come to the boiling-point. Scalding loosens the skins of fruit and vegetables that have to be peeled.” [5]Farmer, Fannie. The Boston Cooking-School Cook Book. Chapter 38: The Canning of Fruits and Vegetables. Accessed Dec 2022 at https://www.bartleby.com/87/0038.html
References
↑1 | Hillman, Howard. The New Kitchen Science: A Guide to Knowing the Hows and Whys for Fun and Success in the Kitchen. Houghton Mifflin Company. Boston: 2003. Page 102. |
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↑2 | McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner. 2004. Kindle Edition. p. 545. |
↑3 | Holmes, ZoeAnn. Why does one scald milk for bread production? In “Food Resource 1996-2006.” Corvallis, Oregon: Oregon State University. Retrieved 4 July 2006 from http://food.oregonstate.edu/faq/bread/bread12.html. |
↑4 | Sarah Tyson Rorer. Mrs Rorer’s New Cook Book. Philadelphia: Arnold And Company. 1903 edition. Page 600. |
↑5 | Farmer, Fannie. The Boston Cooking-School Cook Book. Chapter 38: The Canning of Fruits and Vegetables. Accessed Dec 2022 at https://www.bartleby.com/87/0038.html |