Editing Lactic acid (section)

==== Fermented food ====
{{main|Lactic acid fermentation#Applications}}
Lactic acid is found in many fermented foods.
* Sour [[milk]] products, such as [[kumis]], [[Strained yogurt|laban]], [[yogurt]], [[kefir]], and some [[cottage cheese]]s, derive their flavor from lactic acid. The [[casein]] in fermented milk is coagulated (curdled) by lactic acid.
* Lactic acid is also responsible for the sour flavor of [[sourdough]] bread.
* Some beers ([[sour beer]]) purposely contain lactic acid, one such type being Belgian [[lambic]]s. Most commonly, this is produced naturally by various strains of bacteria. These bacteria ferment sugars into acids, unlike the yeast that ferment sugar into ethanol. After cooling the [[wort]], yeast and bacteria are allowed to "fall" into the open fermenters. Brewers of more common beer styles would ensure that no such bacteria are allowed to enter the fermenter. Other sour styles of beer include [[Berliner weisse]], [[Flanders red]] and [[American wild ale]].<ref>{{cite web|url=https://www.morebeer.com/articles/brewing_with_lactic_acid_bacteria|title=Brewing With Lactic Acid Bacteria|website=MoreBeer}}</ref><ref>Lambic (Classic Beer Style) – Jean Guinard</ref>
* In winemaking, a bacterial process, natural or controlled, is often used to convert the naturally present [[malic acid]] to lactic acid, to reduce the sharpness and for other flavor-related reasons. This [[malolactic fermentation]] is undertaken by [[lactic acid bacteria]].
* [[Pickling]] vegetables in brine creates a sour flavor as bacteria convert sugars into lactic acid.
* [[Fermented sausage]]s

In lists of [[nutritional information]] lactic acid might be included under the term "carbohydrate" (or "carbohydrate by difference") because this often includes everything other than water, protein, fat, ash, and ethanol.<ref>{{cite web|title=USDA National Nutrient Database for Standard Reference, Release 28 (2015) Documentation and User Guide|url=http://www.ars.usda.gov/sp2UserFiles/Place/80400525/Data/SR/SR28/sr28_doc.pdf|page=13|date=2015}}</ref> If this is the case then the calculated [[food energy]] may use the standard {{convert|4|kcal}} per gram that is often used for all carbohydrates. But in some cases lactic acid is ignored in the calculation.<ref>For example, in [https://web.archive.org/web/20181116194139/https://ndb.nal.usda.gov/ndb/foods/show/105?n1=%7BQv%3D1%7D this USDA database entry for yoghurt] the food energy is calculated using given coefficients for carbohydrate, fat, and protein. (One must click on "Full report" to see the coefficients.) The calculated value is based on 4.66 grams of carbohydrate, which is exactly equal to the sugars.</ref> The actual energy density of lactic acid is {{convert|3.62|kcal}} per g.<ref name = "FAOSouthgate">{{cite book |last1=Greenfield |first1=Heather |last2=Southgate |first2=D.A.T.  | name-list-style = vanc |date=2003 |title=Food Composition Data: Production, Management and Use |location=Rome |publisher=[[FAO]] |page=146 |isbn=9789251049495 }}</ref>

While not normally found in significant quantities in fruit, lactic acid is the primary organic acid in [[akebia]] fruit, making up 2.12% of the juice.<ref>{{cite journal |author=Li |first1=Li |last2=Yao |first2=Xiaohong |last3=Zhong |first3=Caihong |last4=Chen |first4=Xuzhong |date=January 2010 |title=Akebia: A Potential New Fruit Crop in China |journal=HortScience |volume=45 |pages=4–10 |doi=10.21273/HORTSCI.45.1.4 |doi-access=free |number=1}}</ref>