Kalenjin sour milk

My friend described it to me as "sour milk", then he was surprised that I already knew that the real name of the drink is Mursik. 

Mursik is a traditional fermented milk variant of the Kalenjin people of Kenya. It can be made from cow or goat milk and is fermented in a specially made calabash gourd locally known as a "sotet". The gourd is lined with soot from specific trees, such as the African senna, which add flavour to the fermented milk. It is normally consumed with ugali or on its own and is served at room temperature or chilled.

Mursik has strong cultural significance for the Kalenjin both in terms of identity as well as socially. It is a common drink in the Rift Valley region and is available in urban areas of Kenya. It has over time become synonymous with Kenyan athletics. A significant majority of Kenyan athletic heroes are Kalenjin and scenes of them receiving a sip of mursik at the airport having returned from international duty form part of Kenya's cultural tapestry.

The drink is prepared primarily from cows' milk (but also less commonly goat's milk, or rarely sheep's milk) fermented in specially made seasoned milk gourds that are pre-treated with the smoke and charcoal of certain species of trees prior to each use. Fresh/raw milk (or, more commonly in modern times, milk that has been first boiled then cooled to ambient temperature) is poured into the specially prepared gourd. The gourd is then capped and placed in a cool dry place to undergo spontaneous fermentation for at least three to five days, through the action of lactic acid bacteria, yeast and mould species.

Prior, the gourds are smeared inside with special charcoal called "osek"; from this, gray lines can be seen when pouring the thick, sour milk.

In preparing the gourd, the Kalenjin women make a brush (sosiot) from a branch of cycad tree used to clean the inside. Brushes made from this tree are hardy and may last for up to two years before replacement.

Charcoal "osek", formed from the smouldering embers of branches from the Ite or Itet tree (African senna) is used as a milk preservative. Women use the embers to coat the inside of the cleaned gourd. The charcoal has various effects. It lines the inside of the gourd, reducing its porosity rendering it airtight. The smoke from the embers also has a preservative effect which prevents undesired bacterial multiplication that causes spoilage, while allowing natural souring. The charcoal smoke imparts a special flavour to the milk, and a bluish colour which is of high aesthetic value to the consumer. Having prepared the gourd, women pasteurise the milk by boiling. The pasteurised milk is left to cool before pouring into the gourd. Finally the gourd is corked to render it airtight, making it possible for the milk to be preserved for up to a month.

Another variant of mursik is called "rotik". This variant contains blood mixed with milk, let to ferment, and has a slightly pink colouration. This variant is rare to come by as the practice of drawing blood from cattle is no longer being practiced widely. This variant is believed to be rich in iron and protein and was given to women who had just delivered or warriors who were wounded in battle. 

Mursik offers probiotic benefits like improved gut health and digestion due to beneficial bacteria, with added advantages from charcoal (detoxification, preservation) but carries potential risks, including high acetaldehyde levels linked to esophageal cancer, alcohol content, and potential digestive upset (bloating, gas) in some individuals, necessitating caution, especially with high consumption.