Inoculation: A small amount of starter culture, which consists of specific strains of lactic acid bacteria (such as Lactobacillus bulgaricus and Streptococcus thermophilus), is added to the cooled milk. The starter culture ferments lactose (milk sugar) into lactic acid, leading to the characteristic tangy flavor and thick texture of yogurt.
Incubation: The milk with the starter culture is placed in a controlled environment, typically in large fermentation tanks or individual containers. The temperature is maintained around 40-45°C to promote the growth of the lactic acid bacteria. During this incubation period (usually 4-8 hours), the bacteria consume lactose and produce lactic acid, causing the milk to thicken and form a gel-like consistency.
Flavoring and Additions: After the desired fermentation time, additional ingredients such as fruit purees, sweeteners, or flavorings can be added to the yogurt to enhance its taste and variety. This step is optional and depends on the desired yogurt product.