Sparging
From Wikipedia, the free encyclopedia
The term sparging has different usages in different contexts.
[edit] In chemistry
In chemical engineering it is commonly used as a method of removing a liquid from a solution by bubbling dry air through the solution. Liquids with higher vapor pressures will tend to evaporate faster than liquids with lower vapor pressures. This is an alternative to distillation, in which liquids with lower boiling points will evaporate faster. Sparging can be safer than distillation because it doesn't require heating the solution to the boiling point of any of its components.
Sparging with air is done in environmental chemistry to remove petroleum contaminants from groundwater and soil. [1]
Sparging is also used in chemistry to remove dissolved gases from a solution by bubbling a different inert gas through the liquid. Nitrogen gas is commonly used to aid in removal of dissolved oxygen gas, preferably when the liquid to be degassed is refluxing under positive nitrogen pressure.
[edit] In brewing
Sparging has another definition as the sprinkling of water. This definition is used in brewing, where it forms part of the lautering process, to describe the addition of water to the drained spent grain to extract remaining sugars into the wort.
In the processing of edible oils, the oil is heated under vacuum to near the smoke point, and water is introduced at the bottom of the oil. The water immediately is converted to steam, which bubbles through the oil, carrying with it any chemicals which are water-soluble. The steam sparging removes impurities that can impart unwanted flavors and odors to the oil.
The term is thought to come from the practice of ancient priests who used green asparagus tips ("Der Spargel" in German) to sprinkle holy water.
