[5] The U.S. Food and Drug Administration defines cream cheese as containing at least 33% milk fat with a moisture content of not more than 55%, and a pH range of 4.4 to 4.9.

[6] Similarly, under Canadian Food and Drug Regulations, cream cheese must contain at least 30% milk fat and a maximum of 55% moisture.

In 1879, to build a larger factory, Lawrence entered into an arrangement with Samuel S. Durland, another Chester merchant.

In 1903, Reynolds sold rights to the "Philadelphia" brand name to the Phenix Cheese Company, which was under the direction of Jason F. Whitney, Sr. (which later merged with Kraft, in 1928).

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)[citation needed] 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.

[citation needed] Inaccurate timing of the heating can produce inferior or unsalable cheese due to variations in flavor and texture.

The only acceptable enzymes that can be used in manufacturing of cream cheese to be sold in Canada are chymosin A and B, pepsin, and rennet.