Pasteurization (American English) or pasteurisation (British English) is a process invented by French scientist Louis Pasteur during the nineteenth century. It is an important step in industrial ice cream producing. Ice cream mix is pasteurized at 155°F (68.3°C) for 30 minutes or 175°F (79.4C) for 25 sec. Besides rendering the mix pathogen-free, pasteurization also helps inactivate naturally occurring enzymes. Inactivation of microorganisms a-nd enzymes reduces the development of undesirable fermentation a-nd enzymatic byproducts a-nd thus, extends mix shelflife a-nd preserves a mild mix flavor. The conditions used to pasteurize ice cream mix are greater than those used for fluid milk because of increased viscosity from the higher fat, solids, a-nd sweetener content, a-nd the addition of egg yolks in custard products.