Once the milk is pasteurised (or not as the case may be), we heat it to between 32 -33oC depending on what we are making and we add starter culture which determines the taste, texture and characteristics of the cheese we are making.
The main microbiological purpose of the starter culture is to turn lactose, milk’s natural sugar in to lactic acid. It is this that we measure during the cheese making process using an acidity meter – see the picture below right.
It is a little known fact that most hard cheeses contain very little lactose and therefore no carbohydrate. My cheese making book, Cheesemaking Practice by R Scott does not give any figures about the lactose content of cheeses, but that old stalwart, Wikipedia does and is reproduced as follows:
Dairy product Serving size Lactose content Percentage
Milk, regular 250 ml 12 g 4.80%
Milk, reduced fat 250 ml 13 g 5.20%
Yogurt, plain, regular 200 g 9 g 4.50%
Yogurt, plain, low-fat 200 g 12 g 6.00%
Cheddar cheese 30 g 0.02 g 0.07%
Cottage cheese 30 g 0.1 g 0.33%
Butter 1 tsp (5.9ml) 0 03 g 0.51%
Ice cream 50 g 3 g 6.00%
Some starter culture contains bacteria that produces carbon dioxide which produces bubbles to make cheeses such as Emmental. It is possible to make your own starter culture, although we do not, we use commercial phage resistant starters from Danisco and Hansens which ensures consistency. Ripening may take between one and two hours depending on what we are making.
And finally, one thing I have learned is that if after your ripening period, your milk is not sufficiently acidic, you will not get a great set and it may take quite a while to set. I have also learned that it is vital to alternate starters to avoid phage. We buy our starters from Orchard Valley.