Editing Curdling

{{Short description|Breaking of an emulsion or colloid into large parts of different composition}}
{{Redirect-multi|2|Curdled|Curdled milk|the 1996 film|Curdled (film)|the 2012 album by Nicole Dollanganger|Nicole Dollanganger}}
{{inline citations|date=July 2019}}
[[File:20130911-OC-RBN-3844 (9736714198).jpg |thumb|A [[cheesemaker]] checks the set of milk curd after vegetable rennet was added to milk]]
'''Curdling''' is the breaking of an [[emulsion]] or [[colloid]] into large parts of different composition through the physio-chemical processes of [[flocculation]], [[creaming (chemistry)|creaming]], and [[coalescence (chemistry)|coalescence]].<ref name=":0">{{Cite web |title=Why does Milk Curdle? |url=https://www.scienceofcooking.com/why-does-milk-curdle.html |access-date=2022-06-10 |website=www.scienceofcooking.com}}</ref> Curdling is purposeful in the production of [[Curd|cheese curd]] and [[tofu]]; undesirable in the production of a [[sauce]], [[fondue|cheese fondue]] or a [[custard]].<ref name=":0" />

== Method ==
[[File:20130911-OC-RBN-3855 (9733481041).jpg|thumb|A curd knife is used to cut milk curd into small cubes]]
[[File:Curdled milk (22413233226).jpg|thumb|A pan of curdled milk]]
In curdling, the pH of the milk decreases and becomes more acidic.<ref name=":0" /> Independently floating [[casein]] molecules attract one another, forming "curdles" that float in a [[Transparency and translucency|translucent]] [[whey]].<ref name=":0" /> At warmer temperatures, the clumping reaction occurs more quickly than at colder temperature.<ref name=":0" /> Curdling occurs naturally if cows' milk is left open in a warm environment to air for a few days.{{Citation needed|date=June 2022}}

== Cheese and tofu ==
{{main|Cheese|Tofu}}
[[File:Curd Setting.jpg|thumb|Cheese curd prior to pressing]]
[[File: Japanese SilkyTofu (Kinugoshi Tofu).JPG |thumb|Silky tofu (kinugoshi tofu)]]

[[Milk]] and [[soy milk]] are curdled intentionally to make [[cheese]] and [[tofu]] by the addition of [[enzyme]]s (typically [[rennet]]), [[acid]]s (including [[lemon juice]]), or various [[salt (chemistry)|salt]]s ([[magnesium chloride]], [[calcium chloride]], or [[gypsum]]); the resulting [[curd]]s are then pressed.<ref>{{Cite web |title=CFR - Code of Federal Regulations Title 21 |url=https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=133 |access-date=2023-08-05 |website=www.accessdata.fda.gov}}</ref>

== Egg sauces ==
{{citationsneeded|section|date=March 2024}}
In hot preparations emulsified with [[Egg (food)|egg]]s 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|date=March 2024}}

==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.<ref>{{cite journal |last1=Brown |first1=Mairi |last2=Laitano |first2=Francesca |last3=Williams |first3=Calum |last4=Gibson |first4=Bruce |last5=Haw |first5=Mark |last6=Sefcik |first6=Jan |last7=Johnston |first7=Karen |title='Curdling' of soymilk in coffee: A study of the phase behaviour of soymilk coffee mixtures |journal=Food Hydrocolloids |date=1 October 2019 |volume=95 |pages=462–467 |doi=10.1016/j.foodhyd.2019.04.032 |s2cid=145932645 |url=https://strathprints.strath.ac.uk/67572/8/Brown_etal_FH_2019_Curdling_of_soymilk_in_coffee_a_study_of_the_phase_behaviour.pdf}}</ref>

== Cheesecake ==
When making [[cheesecake]], if water is added to the cream cheese during the combining period, it will curdle.{{citation needed|date=March 2024}}

==See also==
* [[Cottage cheese]]
* [[Junket (dessert)|Junket]]

== Bibliography ==
* Harold McGee, ''[[On Food and Cooking|On Food and Cooking: The Science And Lore Of The Kitchen]]'', 1984–2004.
* Bethany Moncel [http://foodreference.about.com/od/Dairy/a/Why-Does-Milk-Curdle.htm "Why Does Milk Curdle"] {{Webarchive|url=https://web.archive.org/web/20161217010245/http://foodreference.about.com/od/Dairy/a/Why-Does-Milk-Curdle.htm |date=2016-12-17 }}. Foodreference.about.com.

==References==
{{Reflist}}

{{Cooking techniques}}

[[Category:Cooking techniques]]
[[Category:Culinary terminology]]