|Place of origin||Ukraine|
Ryazhenka (Ukrainian: ряжaнка, Russian: ряженка) is a traditional Ukrainian fermented milk product popular throughout Eastern Europe. It is a variety of yogurt which is made from baked milk by lactic acid fermentation using Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus bacteria cultures. It is milk coffee-coloured and has a traditional taste of farmed dairy products.
Ryazhenka is made by pasteurising milk and then simmering it on low heat for eight hours or longer. Historically, this was done by placing a clay pot (glechik) with milk in the traditional Russian oven for a day until it is coated with a brown crust. Prolonged exposure to heat causes the Maillard reaction between the milk's amino acids and sugars, resulting in the formation of melanoidin compounds that give it a creamy color and caramel flavor. A great deal of moisture evaporates, resulting in a change of consistency. In household production, sour cream (smetana) is subsequently added to trigger fermentation. In modern industrial production, pure thermophile bacterial cultures are added instead. The mixture is then kept in a warm place. The fermentation occurs at temperatures above ca. 40°C / 100°F and usually takes from three to six hours.
The fat content of industrially produced ryazhenka is typically 3.5−4%, but in general it is allowed to vary from <0.5% (if made from skimmed milk) up to 8.9%. The protein content is at least 3%. The carbohydrate content is usually 4−5%. Like scalded milk, ryazhenka is free of harmful bacteria and enzymes and can be stored safely at room temperature for up to forty hours.