Adjust Milk Composition & Blend Ingredients
Milk composition may be adjusted to achieve the desired fat and solids content. Often dry milk is added to increase the amount of whey protein to provide a desirable texture. Ingredients such as stabilizers are added at this time.
2. Pasteurize Milk
The milk mixture is pasteurized at 185°F (85°C) for 30 minutes or at 203°F (95°C) for 10 minutes. A high heat treatment is used to denature the whey (serum) proteins. This allows the proteins to form a more stable gel, which prevents separation of the water during storage. The high heat treatment also further reduces the number of spoilage organisms in the milk to provide a better environment for the starter cultures to grow. Yogurt is pasteurized before the starter cultures are added to ensure that the cultures remain active in the yogurt after fermentation to act as probiotics; if the yogurt is pasteurized after fermentation the cultures will be inactivated.
3. Homogenize
The blend is homogenized (2000 to 2500 psi) to mix all ingredients thoroughly and improve yogurt consistency.
When homogenization is complete, the milk is cooled to between 43-46° C and the starter cultures are added in a concentration of about 2%. It is held at this temperature for about three to four hours
while the incubation process takes place. During this time, the bacteria metabolizes certain compounds in the milk producing the characteristic yogurt flavor. An important byproduct of this process is lactic acid.
the incubation process is done either in a large tank of several hundred gallons and
The yogurt is cooled to 7°C to stop the fermentation process.