Doogh

Doogh is a cold and savoury drink made with fermented milk. Unlike its sister beverage of Turkish origin, ayran, Doogh is not simply diluted yogurt. According to the Ministry of Food Standards in Iran, Doogh "is a drink resulting from lactic fermentation of milk whose dry matter is standardized by diluting yogurt (after fermentation) or buttermilk (before fermentation)." The manufacturing process of Doogh involves a sometimes lengthy period of fermentation in warm temperatures, which comes to be the ultimate cause behind this drink's savoury taste.

Preparation
In order to make doogh, firstly, milk and plain yogurt must be mixed with a ratio of 15:1 until homogeneous. The mixture is then placed on low heat until it has become uniformly warm. Salt is then added, and the mixture is poured into a closed container and placed in a warm area for 3-4 days, after which it becomes ready to serve. The longer the drink is left to ferment in warmth, the more savoury it becomes. Many subcultures in Iran prefer to have the drink after a longer fermentation period.

Etymology
Doogh has historically been referenced in Persian literature as the representation of a "sour version" of milk. The history of this word is unsure. It is present in itself and in its derivatives in Avestan scripture, and essentially seems to have been another word for milk, or, rather, for the product of milking. The word for milking in present-day Persian also derives from this word.

History
In Avestan scripture, doogh is defined as milk through and through. Additionally, in the Avesta, the word for "girl," or "woman," or "female," is dooghtar, which means "the one who milks/is milked," and sounds very similar to the current-day word in Persian for "girl," dokhtar. Some scholars of the Persian language believe that the English word "daughter" also derives from this word.

Doogh is also mentioned in Persian literature from the middle period. Avicenna's Kitab al-Qanun makes use of this word to denote milk that is used in a medicinal process. Though it is true that Avicenna's work was written in Arabic, the word "doogh" doesn't exist in Arabic vocabulary and Avicenna's use of it is thus taken as a part of Persian literature strictly for the purposes of this article.

In culture
Doogh is recognized as one of the main Iranian beverages to serve alongside meals. Dishes such as Dizi and Chelo-Kabab are ones most commonly served with doogh.

In some parts of Iran, primarily the city of Isfahan, doogh is served with a sweet pastry named Gushe-fil as a hallmark tradition and snack.

Doogh is also known in Iranian popular culture to be a sedative agent. One will often hear jokes being made in pop culture about how it is a bad idea to drink doogh during your lunch break at work or school.