The process of heating a liquid—beer, milk, wine—to the point where microorganisms that could cause disease, spoilage, or undesired fermentation are killed. Most inexpensive wines are pasteurized before bottling to keep them from spoiling (which is why jug wines have such a long shelf life and reusable screw caps), but fine wines are rarely pasteurized because it inhibits aging. Gee Whiz Fact: French chemist Louis Pasteur not only invented pasteurization in the late 1800s, he is also credited with discovering the science behind fermentation.