Hardaliye is a grape-based lacto-fermented beverage typical of Eastern Thrace (the European part of Turkey), and particularly the city and province of Kırklareli. It is considered a traditional Ottoman beverage and is thought to have originated at least 500 years ago. Hardaliye is made from grapes and grape juice, mustard seeds, crushed leaves of sour cherry (Prunus cerasus), and benzoic acid. The benzoic acid and the oils in the mustard seeds affect the yeasts that are naturally present on the grapes, preventing alcoholic fermentation from occurring in the juice. In addition to their chemical effects, the mustard seeds impart a distinctive flavor to hardaliye—in fact, the word hardaliye derives from the Turkish hardal, for “mustard.” The sour cherry leaves also enhance the aroma of the beverage. Any kind of grape, whether red or white, can be used to make hardaliye, although dark red varieties are generally preferred, especially if they are aromatic. Historically, the most popular grape for hardaliye production was papaskarasi, and pamit (a white variety known as dimyat in neighboring Bulgaria), adakarasi, and black Muscat were also common. In recent times, international varieties such as syrah and merlot have been introduced to Eastern Thrace and are used for hardaliye, along with the traditional varieties.
The process for making hardaliye is relatively simple: During the harvest season, fresh grapes are crushed and placed in a vessel with alternating layers of mustard seeds (whole, crushed, or heated) and cherry leaves, and then the mixture is left at room temperature. It undergoes lactic acid fermentation for 1-3 weeks, depending on the weather (fermentation is slower when the temperature is cooler). Traditionally, wooden (usually oak) or earthenware vessels were used, but plastic is more common today. The fermenting grape juice is re-circulated every couple of days; when wooden barrels are used, this is done by letting some of the juice out of a tap at the bottom of the barrel and then pouring it back in at the top. After fermentation, the hardaliye is filtered and then stored in bottles, preferably at a temperature of around 4 °C. It may be consumed fresh or left to age for up to 3-4 months. Aged hardaliye may contain some alcohol—in fact, there is usually a very small percentage of alcohol in hardaliye, but it is considered a non-alcoholic beverage; while Orthodox Christian and Jewish communities in Eastern Thrace traditionally turned grapes into wine, the local Muslims, who were not allowed to drink alcohol, made hardaliye as a way to preserve grapes into the winter. In addition to being very tasty (Kemal Atatürk famously liked it so much that he declared it should be the national drink of Turkey), hardaliye also has many beneficial health effects due to the compounds that are contained in the ingredients and that result from fermentation (these include vitamins and antioxidants): It has traditionally been used to boost the immune system, stabilize blood pressure, and keep the circulatory and digestive systems in balance.
Hardaliye was always made at the household level, never as a commercial product. Despite being recognized as a culturally important drink and part of local gastronomic identity in Eastern Thrace, production has declined over the last few decades; one woman from the village of Dolhan (who said that a good hardaliye must be as pure as a teardrop) reported that she learned the recipe from her mother, but that her daughter does not know how to make hardaliye. Researchers studying the chemical composition and health benefits of this traditional beverage have recommended that a standardized production procedure be developed in order to keep hardaliye on the market, and have advocated using starter cultures and pasteurization for a more consistent, shelf-stable product; there is now a handful of industrial producers, who release an estimated 200 thousand liters of hardaliye onto the market each year. While this is preferable to hardaliye disappearing altogether, the industrial product bears only superficial resemblance to the natural, unpasteurized, traditional one, which reflects the diversity of the region’s microflora and the variations in household production methods.