Normally, an enzyme called rennet is a vital ingredient for making cheese; it separates the milk into curds and whey. If you don't have rennet, though, acids from citrus or vinegar can do the trick—up to a point. Traditional

rennet is derived from the stomachs of calves

or lambs before they progress from a milk-only diet. However, there's also a vegetarian version made from a particular type of mold. A weaker alternative is junket. Rennet is active between 85 and 140 degrees Fahrenheit, but is most potent up to 105 degrees. Once milk’s acidity falls to a pH level of 4.6 and while its temperature rises to 165 degrees Fahrenheit, the casein suspended in the mixture separates into curds. Here's how to achieve that with either vinegar or citric acid.

The process requires only milk, either distilled vinegar or fresh lemon juice, and salt to taste

. The higher the fat content in the milk, the better, but steer clear of UHT (ultra-high temperature) milk—the process of sterilizing milk by heating it to 280 degrees Fahrenheit for two seconds alters the protein structure, leaving the milk unable to separate.

Make Paneer

Paneer is a traditional mild cheese in Indian cuisine.

Bring the milk to a low simmer

so that it foams without burning. Remove from heat and

add lemon juice 1 tablespoon at a time

. At the right balance, the milk will curdle.

Leave the milk to sit for 10 minutes

, during which time it should separate completely.

Strain the curds through a cheesecloth

laid within a colander or sieve.

Squeeze out any excess liquid

, and lay the cheesecloth flat on a chopping board. Sprinkle the curd with salt, then

wrap the cheesecloth into a tight bundle

in the shape of a block.

Press the curd block between two heavy plates

and leave it to dry for an hour. The cheese is good to eat immediately, with no aging required, but only keeps for a couple of days in the refrigerator.

Make Queso Fresco

Making queso fresco, a Latin-American version of paneer, involves adding distilled vinegar gradually to the warm milk. The vinegar has a more neutral flavor than bright, tangy lemon juice.

Make Ricotta

Authentic ricotta is made using leftover whey from cheese made with yogurt or rennet, but you can create a homemade version just as you would paneer. Drain off the excess liquid, but skip pressing it out into a block to get a wetter, smoother cheese.

Make Cottage Cheese

Cottage cheese, like ricotta, is drained but not pressed. The easiest way to make it at home is to heat up milk and buttermilk with salt. Buttermilk is the residue from cream that's been churned into butter, and it turns acidic as it ferments. As you heat it, the milk separates into curds. The more fat in the buttermilk, the higher the temperature must be for it to curdle.

Make Mascarpone

Mascarpone is cream cheese–like, and it's the key ingredient in tiramisu. Use heavy or whipping cream and lemon juice. Because of the higher fat content, cream's temperature needs to rise to about 190 degrees Fahrenheit, and the liquid won’t separate as distinctly as milk. Mascarpone doesn’t need to be squeezed and has a consistency similar to custard.