Soured milk
Encyclopedia
Soured milk is a food product, distinguished from spoiled milk
, and is a general term for milk that has acquired a tart taste, either through the addition of an acid, such as lemon juice or vinegar, or through bacterial fermentation. The acid causes milk to coagulate and form a thicker consistency. Soured milk that is produced by bacterial fermentation is more specifically called fermented milk or cultured milk. Soured milk that is produced by the addition of an acid, with or without the addition of microbial organisms, is more specifically called acidified milk. In the US, the acids that may be used in the manufacture of acidified milk are acetic acid
(commonly found in vinegar), adipic acid
, citric acid
(commonly found in lemon juice), fumaric acid
, glucono-delta-lactone, hydrochloric acid
, lactic acid
, malic acid
, phosphoric acid
, succinic acid
, and tartaric acid
.
Since the 1970s, sour milk has been used both for chemically and biologically soured milk.
Some older recipes list "sour milk" as an ingredient, but today it is unclear which dairy product was "sour milk". Pasteurized milk was not available in the US until the early 1900s, and only became universal in Canada by 1938. For example, the South Jersey Milk Company created a poster in 1930 entitled "What is pasteurized milk?" to educate the American public about the safety of its newly pasteurized milk. Thus, older recipes that use sour milk may have been written prior to the availability of pasteurized milk, when it would be milk that had naturally acquired a sour taste through bacterial fermentation at room temperature. In fact, even in the ice refrigerators in use before rural electrification, raw milk would sour within 2 days.
However, Pasteur's original pasteurization, heating to 145°F for 30 minutes, does not destroy all bacteria - such milk can still sour naturally at room temperature and in baking is very similar to raw sour milk. Today, pasteurization usually means
HTST processing
, heating to 161°F, which kills virtually all souring organisms.
At least until the 1920s, there was a clear distinction between sour milk and buttermilk, where buttermilk
was the thin liquid leftover from making butter. Today, in North America, either cultured buttermilk, also commonly known as buttermilk but not the same product as the aforementioned buttermilk, or milk soured by the addition of lemon juice or vinegar is often used when sour milk is needed in a recipe. However, home made (live) yoghurt is a better replacement.
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
, and is a general term for milk that has acquired a tart taste, either through the addition of an acid, such as lemon juice or vinegar, or through bacterial fermentation. The acid causes milk to coagulate and form a thicker consistency. Soured milk that is produced by bacterial fermentation is more specifically called fermented milk or cultured milk. Soured milk that is produced by the addition of an acid, with or without the addition of microbial organisms, is more specifically called acidified milk. In the US, the acids that may be used in the manufacture of acidified milk are acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
(commonly found in vinegar), adipic acid
Adipic acid
Adipic acid is the organic compound with the formula 42. From the industrial perspective, it is the most important dicarboxylic acid: About 2.5 billion kilograms of this white crystalline powder are produced annually, mainly as a precursor for the production of nylon...
, citric acid
Citric acid
Citric acid is a weak organic acid. It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks...
(commonly found in lemon juice), fumaric acid
Fumaric acid
Fumaric acid or trans-butenedioic acid is the chemical compound with the formula HO2CCH=CHCO2H. This white crystalline compound is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid. In fumaric acid the carboxylic acid groups are trans and in maleic acid they are cis...
, glucono-delta-lactone, hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
, lactic acid
Lactic acid
Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...
, malic acid
Malic acid
Malic acid is an organic compound with the formula HO2CCH2CHOHCO2H. It is a dicarboxylic acid which is made by all living organisms, contributes to the pleasantly sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms , though only the L-isomer exists...
, phosphoric acid
Phosphoric acid
Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...
, succinic acid
Succinic acid
Succinic acid is a dicarboxylic acid. Succinate plays a biochemical role in the citric acid cycle. The name derives from Latin succinum, meaning amber, from which the acid may be obtained....
, and tartaric acid
Tartaric acid
Tartaric acid is a white crystalline diprotic organic acid. It occurs naturally in many plants, particularly grapes, bananas, and tamarinds; is commonly combined with baking soda to function as a leavening agent in recipes, and is one of the main acids found in wine. It is added to other foods to...
.
Sour milk in recipes
In recipes, soured milk created by the addition of an acid or by bacterial fermentation can often be used interchangeably. For example, 1 cup of cultured buttermilk, a soured milk produced by bacterial fermentation, can be replaced by 1 tablespoon of lemon juice or vinegar plus enough milk to make 1 cup. The chemically soured milk can be used after standing for 5 minutes.Sour milk
Currently, sour milk commonly means milk that has spoiled and is "in an unpalatable state". However, the meaning of sour milk can be ambiguous since it has been used in different contexts in different time periods.Since the 1970s, sour milk has been used both for chemically and biologically soured milk.
Some older recipes list "sour milk" as an ingredient, but today it is unclear which dairy product was "sour milk". Pasteurized milk was not available in the US until the early 1900s, and only became universal in Canada by 1938. For example, the South Jersey Milk Company created a poster in 1930 entitled "What is pasteurized milk?" to educate the American public about the safety of its newly pasteurized milk. Thus, older recipes that use sour milk may have been written prior to the availability of pasteurized milk, when it would be milk that had naturally acquired a sour taste through bacterial fermentation at room temperature. In fact, even in the ice refrigerators in use before rural electrification, raw milk would sour within 2 days.
However, Pasteur's original pasteurization, heating to 145°F for 30 minutes, does not destroy all bacteria - such milk can still sour naturally at room temperature and in baking is very similar to raw sour milk. Today, pasteurization usually means
HTST processing
Pasteurization
Pasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food...
, heating to 161°F, which kills virtually all souring organisms.
At least until the 1920s, there was a clear distinction between sour milk and buttermilk, where buttermilk
Buttermilk
Buttermilk refers to a number of dairy drinks. Originally, buttermilk was the liquid left behind after churning butter out of cream. It also refers to a range of fermented milk drinks, common in warm climates where unrefrigerated fresh milk otherwise sours quickly...
was the thin liquid leftover from making butter. Today, in North America, either cultured buttermilk, also commonly known as buttermilk but not the same product as the aforementioned buttermilk, or milk soured by the addition of lemon juice or vinegar is often used when sour milk is needed in a recipe. However, home made (live) yoghurt is a better replacement.