Silivri Yogurt

Description and Distinguishing Features of Silivri Yogurt:

Silivri Yogurt is a yogurt produced with a mixture of cow, sheep, buffalo milk, either 50% cow - 50% sheep or 50% cow - 50% buffalo milk. It has a yellowish color, a dense texture, and a thick layer of rough cream on top.Silivri Yogurt is produced in two ways: traditional and industrial. It is fermented using a starter culture at a ratio of 1.5-3%. The pasteurization process is conducted over an extended period, and a second cooking process, known as "cream cooking," is applied. Due to these geographically specific methods, it possesses a distinctive cream layer.

Silivri Yogurt

The sale of Silivri Yogurt that is fermented in glass or clay containers is also carried out in the same containers. The history of Silivri Yogurt dates back to the 1870s. Yogurts produced in yogurt factories built exclusively for yogurt production in Silivri were transported to Istanbul by sea for distribution. When complaints arose about the cream layer of the transported yogurts getting spoiled due to shaking during transportation, geographically specific methods were developed to prevent the cream from spoiling. Since the 1930s, Silivri Yogurt has been sent to major cities such as Izmir and Ankara, and its reputation is closely tied to its geographical origin.

Traditional Production of Silivri Yogurt:

The traditional production of Silivri Yogurt takes place in yogurt factories consisting of two separate sections: the boiler room where the milk is cooked and the ground where the fermentation occurs, lined up side by side at a height of 30-40 cm, called "karavana stoves."

After acidity tests are conducted on the milk brought to the yogurt factory, the milk is filtered through cheesecloth or a fine sieve and transferred to cooking boilers. The milk is continuously stirred vigorously with special wooden paddles called "pala" to prevent sticking to the bottom, and it is pasteurized at a temperature of 84-90 °C for 150 minutes. During this process, a significant amount of water evaporates from the milk, increasing the dry matter content. Once pasteurization is complete, the milk is filled into glass or clay containers (1, 2, 3, or 5 kg, depending on preference). The pouring/filling process is done from a height, and the foam generated during this process ensures that the cream layer is shaped and frothy. These containers are then placed in copper or stainless steel basins (troughs) filled with water. Care is taken to ensure that the water level in the basins is slightly above the halfway mark of the containers. Containers of the same height are placed in the same basins.

For the distinctive feature of Silivri Yogurt, a second cooking/heating process known as "cream cooking" is applied by igniting the fire beneath the basins containing the filled containers, reaching a temperature of 70 °C for 30-60 minutes. During this time, the fat layer collects on top of the containers, forming a thick cream layer. At the end of the process, the fire/flame under the basins is extinguished, and the milk is left to cool naturally to the fermentation (fermentation) temperature of 42-43°C. After the cream layer has formed, a pre-prepared starter culture is added to the milk in the containers with a syringe at a ratio of 1.5-3%, ensuring not to disturb the cream layer.

The basins where the containers are placed are covered with clean cloth covers, windows are closed, and the milk is left to ferment for 3-4 hours. Once fermentation is complete (coagulation formation/yogurtization is checked), the covers are removed, windows are opened, and the yogurt is allowed to cool thoroughly. After the yogurts have cooled in cold storage rooms (4±2 °C) for at least 6 hours, the plastic covers of the containers are closed, arranged in crates, and made ready for shipment. The shipment of yogurt is done with vehicles equipped with cold storage (4±2 °C), and the cold chain is maintained until it reaches the consumer. The shelf life of traditionally produced Silivri Yogurts is 15 days if the cold chain at 4±2 °C is not broken.

Upon arrival at the facility, acidity, fat, dry matter, and antibiotic tests are conducted on the milk. Once suitable milk is accepted, it undergoes cleaning and separation in a separator. In productions made from 100% cow's milk, standardization of dry matter and fat is performed. The milk is preferably heated under vacuum to at least 75-85 °C for the fat-free dry matter to be a minimum of 10%, and the fat to rise to 4%. This process is not applied in the case of a mixture of buffalo and sheep milk. The standardized milk, with standardized dry matter and fat, is pasteurized at 90-95°C for 30 minutes. Pasteurized milk is hot-filled into containers (optionally 0.5, 1, 3, or 5 kg glass or clay containers).

The yogurt containers placed in four-tiered yogurt trolleys made of stainless steel are taken to the fermentation room. Before filling, hot air fans are turned on, and the room is heated to 45-50 °C. The hot air fans operate continuously during the filling of the milk into the containers.

The filling process into the containers is carried out by lifting the filling hose/pipe upward and pouring it from a height to create foam. After the filling process is completed, the doors and windows of the fermentation room are closed, and the room temperature is maintained above 50 °C with the hot fans. Rooms containing containers filled with hot milk are heated with fans for at least 2 hours. These procedures are crucial for the formation of the distinctive rough and thick cream layer of Silivri Yogurt. At the end of the waiting period, the steam valves of the room fans are closed, ventilation fans are turned on, and the milk is allowed to cool on its own until it reaches the fermentation temperature of 45-48 °C. A pre-prepared starter culture at a ratio of 1.5-3% is added to the milk that has formed cream, without disturbing the cream layer, using a fermentation gun from the edge of the container by 2-3 cm. The ventilation fans of the fermentation rooms are closed again, and the room temperature is adjusted to 42-45 °C with the operation of hot air fans.

After approximately 2-3 hours (until pH=4.6), the fermentation time is completed, the hot air fans are turned off, ventilation fans are turned on, and the yogurt is quickly cooled to room temperature. Subsequently, the trolleys containing the yogurt containers are placed in cold storage rooms and cooled to 4±2 °C (for at least 6 hours). After the cooling process, the plastic covers of the yogurt containers are closed, arranged in crates, and made ready for shipment. The shipment of yogurt is carried out with vehicles equipped with cold storage (4±2 °C), maintaining the cold chain until it reaches the consumer. The shelf life of industrially produced Silivri Yogurts is 20 days if the cold chain at 4±2 °C is not broken.