One of the key stages in the cheese production process is the addition of a starter culture, which plays an important role in shaping the texture, aroma, and flavor of the final product.
In this article, we will explore how and why to add mesophilic and thermophilic starter cultures during cheese production.
What are mesophilic and thermophilic starter cultures?
Starter cultures are bacterial cultures that help ferment milk, turning it into cheese.
Mesophilic cultures are active at temperatures ranging from 20 to 40 degrees Celsius, while thermophilic cultures prefer higher temperatures — from 40 to 55 degrees Celsius.
These cultures not only aid in the souring of milk but also influence the taste and texture of cheese.
Why add starter culture?
The addition of starter culture is necessary for:
- The souring process: The bacteria in the starter culture convert lactose into lactic acid, leading to the souring of milk.
- The formation of aroma: Different strains of bacteria provide unique flavor and aromatic profiles that define the character of the cheese.
- The creation of texture: Starter cultures influence the formation of the curd and its subsequent processing, ultimately affecting the texture of the cheese.
How to add starter culture?
The process of adding starter culture begins with the preparation of the milk.
If you store the culture in the freezer, take the starter out 2-3 hours before use so that it can warm up to room temperature.
1-5 minutes before adding the culture to the milk, open the flask and place the required amount of culture on foil, returning the rest back to the freezer.
Milk preparation. The milk should be fresh and pasteurized (or raw, depending on the recipe).
The temperature of the milk must be brought to the recommended level for your type of starter culture (mesophilic cultures: 33-36 degrees, thermophilic: 40-45 degrees).
After that, there are two approaches to adding the starter culture.
- Sprinkling the starter culture on the surface of the milk. The starter culture, usually in powder form, is sprinkled on the surface of the milk and allowed to absorb for 1-3 minutes. Then the milk is gently stirred to ensure even distribution of the culture.
- Pre-diluting the starter culture. The starter culture is pre-diluted in a small amount of warm milk or water, and then this solution is added to the main quantity of milk while stirring thoroughly.
The choice of method may depend on the type of starter culture (dry or liquid).
Dry starter cultures are often simply sprinkled on the surface, while liquid or more concentrated cultures may be diluted before being added.
In any case, after adding the starter culture, it must be mixed thoroughly but gently for even distribution.
After that, the milk with the starter culture is left for a certain time for fermentation, while maintaining the temperature of the milk within the suitable range for the chosen type of starter culture.
Which type of starter culture to choose?
So, which type of starter culture should be chosen for cheese production?
It is best to use the type of starter culture specified in the recipe. However, if you do not have that type of culture, you should understand whether it can be replaced with another.
Mesophilic cultures are suitable for cheeses that do not require heating to high temperatures. They should not be used if there is significant heating of the milk during the cheese production process or if the cheese mass is processed in hot water.
Mesophilic cultures provide a mild, delicate flavor and the correct texture, making them ideal for most soft and semi-hard cheeses.
Examples of cheeses that use mesophilic cultures: Cheddar, Gouda, Camembert, Brie, Feta, Gorgonzola.
Thermophilic cultures are active at higher temperatures, making them indispensable for cheeses that undergo heat treatment.
These cultures contribute to the formation of a denser texture and bright, rich flavor.
Examples of cheeses that use thermophilic cultures: Parmesan, Gruyere, Emmental, Mozzarella, Pecorino, Yogurt.
Storage of starter cultures
An unopened starter culture should be stored in a cool, dry place away from direct sunlight.
The optimal storage temperature is between 4°C and 20°C. It is best to store the starter culture in the refrigerator to extend its shelf life.
Opened starter culture
After opening, the starter culture should be stored in the refrigerator at a temperature of 4°C to 8°C.
Typically, the shelf life is 3-6 months.
It is recommended to place the starter culture in an airtight container to protect it from contamination and moisture.
Regularly check the starter culture for changes in color, smell, or texture.
Freezer storage
Storing starter culture in the freezer can extend its shelf life to 12 months or more.
It is important to remember a few points.
Preparation for freezing. Before freezing, make sure the starter culture is in an airtight container or vacuum bag. This will prevent moisture and foreign odors from entering.
Thawing. When you decide to use frozen starter culture, thaw it slowly in the refrigerator.
Quick thawing at room temperature can negatively affect the quality of the starter culture.
Starter culture activity after thawing. After thawing, the starter culture may require more time to activate.
What can replace starter culture?
At home, in the absence of specialized starter cultures, you can use alternatives such as sour cream, yogurt, or kefir.
These products contain live lactic acid bacteria that can perform functions similar to mesophilic cultures.
Sour cream
To use sour cream as a starter culture, choose a product with a high fat content (at least 20%) and without additives.
Add 1-3 tablespoons of sour cream per liter of milk and mix well. Leave the milk for several hours for fermentation (or follow the instructions for the specific cheese).
This method is suitable for producing soft cheeses such as cottage cheese or cream cheeses.
Sour cream works best at temperatures around 30°C, making it a good substitute specifically for mesophilic cultures.
Yogurt
Yogurt contains thermophilic bacteria that work well at higher temperatures (around 40-45°C).
This makes yogurt a suitable alternative for producing cheeses that require thermophilic starter cultures, such as mozzarella or cheddar.
Add 1-3 tablespoons of natural yogurt per liter of milk and mix well. Leave the milk for 4-6 hours for fermentation.
Use yogurt without additives and with live cultures to achieve the desired result. You can also use homemade yogurt, which usually contains active and more diverse strains of bacteria.
Kefir
Kefir can be used to replace both mesophilic and thermophilic starter cultures due to its diverse composition of bacteria and yeasts.
It can be particularly useful for producing cheeses with combined starter cultures or if you want to experiment with new flavors.
Add 50-100 ml of kefir per liter of milk, mix, and leave at room temperature for 12-24 hours, depending on the desired level of acidity and thickness.
Kefir starter culture works more slowly than specialized cultures.
This method is suitable for softer and tangy cheeses.
