Cream cheese is easy to make at home, and many methods and recipes are used. Consistent, reliable, commercial manufacture is more difficult. Normally, protein molecules in milk have a negative surface charge, which keeps milk in a liquid state; the molecules act as surfactants, forming micelles around the particles of fat and keeping them in emulsion. Lactic acid bacteria are added to pasteurized and homogenized milk. During the fermentation around 22 °C (72 °F), the pH of the milk decreases (it becomes more acidic). Amino acids at the surface of the proteins begin losing charge and become neutral, turning the fat micelles from hydrophilic to hydrophobic state and causing the liquid to coagulate. If the bacteria are left in the milk too long, the pH lowers further, the micelles attain a positive charge, and the mixture returns to liquid form. The key, then, is to kill the bacteria by heating the mixture to 52–63 °C (126–145 °F) at the moment the cheese is at the isoelectric point, meaning the state at which half the ionizable surface amino acids of the proteins are positively charged and half are negative.
Inaccurate timing of the heating can produce inferior or unsalable cheese due to variations in flavor and texture. Cream cheese has a higher fat content than other cheeses, and fat repels water, which tends to separate from the cheese; this can be avoided in commercial production by adding stabilizers such as guar or carob gums to prolong its shelf life.
Cream cheese is often spread on bread, bagels, crackers, etc., and used as a dip for potato chips and similar snack items, and in salads. It can be mixed with other ingredients, such as yogurt or pepper jelly, to make spreads.
Cream cheese can be used for many purposes in sweet and savoury cookery, and is in the same family of ingredients as other milk products, such as cream, milk, butter, and yogurt. It can be used in cooking to make cheesecake and to thicken sauces and make them creamy. Cream cheese is sometimes used in place of or with butter (typically two parts cream cheese to one part butter) when making cakes or cookies, and cream cheese frosting. It is the main ingredient in the filling of crab rangoon, an appetizer commonly served at U.S. Chinese restaurants. It can also be used instead of or with butter or olive oil in mashed potatoes, and in some westernized sushi rolls.