Warming the Milk
The milk called for in the recipe is warmed to a temperature appropriate for the culture that will be used. This is often done in a “double boiler” fashion, by placing the pot of milk in a larger pot, or sink, of warm water. This process must be done slowly as the quality of the cheese depends on slow warming in this and subsequent steps. The highest available quality of milk should be used. It is possible to use goat, ewe or cow’s milk in any recipe, although most recipes call for a specific type of milk.
Ripening the Milk
Either naturally occurring lactic bacteria or added bacterial cultures are used to acidify the milk through the digestion of lactose (a sugar) into lactic acid. The use of direct set cultures helps ensure consistency across batches. The correct temperature of the milk, as called for in the recipe, must be maintained during the ripening process.
Additives
Once the milk has ripened, you can add other ingredients that may be optional or may be necessary for a specific type of cheese. These could be: coloring, additional cultures, calcium chloride, or lipase (for flavor in certain cheeses). These must be added one-at-a-time prior to adding the rennet. They are usually diluted in a small amount of cool bottled water prior to adding them to the milk. And, they must be well incorporated into the milk by stirring gently from bottom to top.
Coagulation
During this step, the milk turns into a solid curd. Rennet is usually added to create this reaction which can take 30 minutes to 24 hours. The minimum amount of rennet that causes the desired reaction should be used. It should be diluted in some cool bottled water prior to stirring it into the milk. It should be combined well, but do not stir for more than a couple of minutes. If substituting goat or ewe milk for cow milk in a recipe, decrease the rennet by 20%. The pot temperature should be regulated and kept constant during the renneting process, and the pot should be covered and left undisturbed.
Some cheeses are coagulated without the use of rennet (or with the use of very small amounts). In these cheeses the coagulation process is produced by lactic bacteria turning lactose into lactic acid. Most cheeses, however, do call for the use of rennet to compliment and speed this process.
Another form of coagulation is direct acid addition to the milk. Vinegar, lemon juice or citric acid may be added to the milk to force coagulation in heat-treated milk.
Cutting the Curd
Once “set” and a “clean break” is achieved, the curds are cut—usually into cubes of a specific size—in order to encourage the curd to separate from the whey. This should be done gently. I use a long kitchen knife and cut the curds into squares (as viewed from the top down), then angle the knife to make diagonal cuts. For harder cheeses, the curds are cut smaller; for softer cheeses, larger. The consistency of the curd before cutting, and the cut curds will determine the final texture of the cheese.
After cutting, the curds can be stirred to further promote separation of curds from whey, although many recipes recommend allowing the cut curds to set for a while before starting the stirring and cooking process.]
Cooking and Stirring
The objective of this step is to further develop acidity and to cause the expulsion of whey from the curd. Not all cheeses undergo this step. Refer to the recipe. Gentleness is called for!
For harder cheeses where cooking and stirring is used, the temperature must be increased very slowly, no more than 2