Curdling

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Checks the set of the milk curd after vegetable rennet was added to the milk. 20130911-OC-RBN-3844 (9736714198).jpg
Checks the set of the milk curd after vegetable rennet was added to the milk.

Curdling is the breaking of an emulsion or colloid into large parts of different composition through the physio-chemical processes of flocculation, creaming, and coalescence. [1] Curdling is purposeful in the production of cheese curd and tofu; undesirable in the production of a sauce, cheese fondue or a custard. [1]

Contents

Method

Cuts the milk curd with a curd knife in small cubes. 20130911-OC-RBN-3855 (9733481041).jpg
Cuts the milk curd with a curd knife in small cubes.
A pan of curdled milk Curdled milk (22413233226).jpg
A pan of curdled milk

In curdling, the pH of the milk decreases and becomes more acidic. [1] Independently floating casein molecules attract one another, forming "curdles" that float in a translucent whey. [1] At warmer temperatures, the clumping reaction occurs more quickly than at colder temperature. [1] Curdling occurs naturally if cows' milk is left open in a warm environment to air for a few days.[ citation needed ]

Cheese and tofu

Cheese Curd prior to pressing Curd Setting.jpg
Cheese Curd prior to pressing
Silky tofu (kinugoshi tofu) Japanese SilkyTofu (Kinugoshi Tofu).JPG
Silky tofu (kinugoshi tofu)

Milk and soy milk are curdled intentionally to make cheese and tofu by the addition of enzymes (typically rennet), acids (including lemon juice), or various salts (magnesium chloride, calcium chloride, or gypsum); the resulting curds are then pressed. [2]

Egg sauces

In hot preparations emulsified with eggs like hollandaise and custard, curdling is the undesirable result of overheating the sauce. Sauces which contain starch curdle with more difficulty.

In cold sauces like mayonnaise as well as in hot sauces, too large a ratio of fat to egg may also cause curdling.

Milk sauces

In sauces which include milk or yogurt, overheating often causes curdling. The higher the fat content, the less likely curdling is. Strained yogurt used in sauces also curdles only with difficulty.[ citation needed ]

Coffee

When a plant based milk such as soya milk is added to coffee, curdling can sometimes occur. To help prevent this manufacturers sometimes add acidity regulators. [3]

Cheesecake

When making cheesecake, if water is added to the cream cheese during the combining period, it will curdle.[ citation needed ]

See also

Bibliography

Related Research Articles

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<span class="mw-page-title-main">Custard</span> Semi-solid cooked mixture of milk and egg

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<span class="mw-page-title-main">Strained yogurt</span> Yogurt thickened by draining whey

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<span class="mw-page-title-main">Quark (dairy product)</span> Acid-set cheese

Quark or quarg is a type of fresh dairy product made from milk. The milk is soured, usually by adding lactic acid bacteria cultures, and strained once the desired curdling is achieved. It can be classified as fresh acid-set cheese. Traditional quark can be made without rennet, but in modern dairies small quantities of rennet are typically added. It is soft, white and unaged, and usually has no salt added.

References

  1. 1 2 3 4 5 "Why does Milk Curdle?". www.scienceofcooking.com. Retrieved 2022-06-10.
  2. "CFR - Code of Federal Regulations Title 21". www.accessdata.fda.gov. Retrieved 2023-08-05.
  3. Brown, Mairi; Laitano, Francesca; Williams, Calum; Gibson, Bruce; Haw, Mark; Sefcik, Jan; Johnston, Karen (1 October 2019). "'Curdling' of soymilk in coffee: A study of the phase behaviour of soymilk coffee mixtures" (PDF). Food Hydrocolloids. 95: 462–467. doi:10.1016/j.foodhyd.2019.04.032. S2CID   145932645.