For making mozzarella cheese, you will need a thermophilic culture, as well as rennet (the inner lining of the calf's stomach): both of these products can be purchased at cheese making supply stores, or online.
In addition, be sure to use a non-iodized salt, such as Kosher salt or sea salt, for the brine for the cheese (if you choose to make the brine.) The other ingredients and equipment required will be found in your home.
Mozzarella cheese is a firm, unripened cheese that originated from Italy.
It has a very delicate and mild flavour, and some would argue that its texture is almost plastic-like. Nevertheless, mozzarella has wonderful shredding and melting properties, and for those reasons, it is used extensively in snacks, on pizza, in lasagna, and in many other casseroles.
Mozzarella is primarily made from whole cow's milk nowadays, but long ago, it was made mostly from bufala, the milk from the female water buffalo. Because milk from the water buffalo is very rare (not to mention, very expensive), cow's milk has become the chosen, less expensive, alternative dairy product for making mozzarella cheese.
Sterilize all equipment.
Heat milk, in large pot or oven, to 90o F, using medium-low heat. Stir frequently to distribute heat.
After milk reaches 90o F, add culture; stir well to combine.
Cover milk and allow to ferment, undisturbed, for approximately 45 minutes
After 45 minutes, check temperature of milk (it should still be at 85 - 900 F); stir well.
Slowly stir in rennet, using an up-and-down motion to distribute rennet evenly throughout the milk.
Allow milk to sit again; this time, for 60 - 90 minutes. You should see the curds starting to separate from the whey. They whey should look slightly yellowish in colour and should be floating on top of the curd.
Now take the knife and cut the curds into 1/2-inch cubes.
Let sit, without stirring, for 20 minutes.
During the next 30 minutes, slowly reheat the curds to 100o F; stir frequently. When you stir, the curds will shrink in size.
Check temperature. At 100o F, turn off heat. Let curds sit for approximately 5 minutes.
Drain the whey from the curds, using the colander.
Fill sink with water (temperature: 110 - 120o F); place pot into sink. Let pot sit in sink for up to 3 hours.
At 30-minute intervals, and using clean hands, press whey from curds.
To get your balls of mozzarella, cut the curds into 4 equal pieces.
Put on rubber gloves.
Heat water to 180o F. Pour over the mozzarella ball, working it (almost kneading it) until it is shiny and smooth. Once cheese is "stretchy," form it into a ball and put into a bowl of cold ice water for 5 minutes to firm it up.
Combine 16 ounces of Kosher salt with 1 gallon of water to make brine.
Leave mozzarella balls in the brine for approximately 2 hours; remove and pat dry. Refrigerate.