Cultures are bacteria that are in the air, naturally in the milk (especially in unpasteurized) and intentionally added at the start of the cheese making process. They consume the milk’s lactose, producing lactic acid which makes the milk more acidic or sour and thus creating the best climate for the curd to form. The more acidic the milk becomes, the easier it is for the curd to expel the whey. They also play a key role in the aroma, texture, and flavour generated as the cheese is matured.
As milk naturally has bacteria, if left too long it will naturally sour and curdle, if left uncovered and warm it will pick up airborne bacteria and quickly become sour. In cheese making, specific cultures are intentionally added at the start of the cheese making process to accelerate this process and to create, with aging, a certain aroma, texture, and flavour.
There are two groups of these starter cultures:
- Mesophilic Cultures can only withstand up to 30 C/102 F and thus are commonly used when the curds are not heated above that temperature such as when making Gouda and Cheddar.
- Thermophilic Cultures can withstand up to 55 C/132 F and thus are commonly used when the curds are not heated above that temperature such as when making Swiss or harder Italian cheeses.
There are two formats of these starter cultures:
- Mother Culture.
- Direct Set Culture.
For beginner cheese makers, the simplest way to start is to use store bought buttermilk that contains live culture for a mesophilic starter or store bought yogurt for a thermophilic culture. The next stage in Cheese Making is to additionally use some cheese that you are trying to make to provide that bacteria or inoculation. The third is using refined commercial cultures like the commercial cheese makers do.
The commercially cultures are made in a variety of choices from a variety of manufacturers with a variety of product lines using a variety of natures many many bacteria. This results in a large range of confusion as many cheese making recipes name manufacturers’ products rather than the actual culture or cultures required. These products are in general not available in small hobby-craft cheese making dosage sized packages as the market size is too small. Thus cheese making supply stores sell amounts that they divide or the smallest packages available and ask their customers to divide. The following section is to aid in some organization and understanding of this subject.