Karin Heineman, Inside Science TV –  Beer! Most Americans choose it over all other alcoholic beverages.

It's also one of the world's oldest beverages. In fact the first evidence of beer production dates back to Ancient Egypt and Mesopotamia in the fifth millennium BC. People have been brewing beer for a very long time, even before anyone really understood what turns its ingredients into alcohol.

So what's the science behind beer? Cynthia McKelvey, a science journalist at the University of California Santa Cruz and beer enthusiast, breaks down the brewing process for us in a few simple steps.

"The first thing you're going to do when you're brewing beer is you're going to … go through the malting process. You take the barley, you soak it in water and that's to start the germination or the sprouting process."

This germination will break the starches down into smaller bits that then go to the kiln where these broken down starches are baked dry.

"Then after that you're going to mash it," explained McKelvey.  

"Mashing is taking that malted barley and putting it in hot water to activate the enzymes that break down the starches into sugars."

After mashing down the malted barley comes the boiling process. This is where a great deal of flavor is added.  Any hops the brewer wants to add to give the beer a distinctive bitter taste and balance out the sweetness (think India Pale Ales) are added now.

"Then it's moved to the fermentation tank where it's cooled down, yeast is added and the yeast essentially eats the sugar and breaks it down into carbon dioxide and ethanol. So it gives beer its natural fizz and makes it alcoholic," said McKelvey.

Some brewers add an additional fermentation step to further alter the taste of the beer.

"[During] secondary fermentation you take the beer, you siphon it out into a clean sterile tank, and then the yeast just keeps going, keeps breaking those sugars down to alcohol and carbon dioxide, and it just gives a cleaner and crisper flavor, and color to the beer," said McKelvey.

And the key to all beer: saccharomyces!

"With traditional beer you're brewing it with a yeast called saccharomyces … it works very, very quickly and it mostly just powers through all the sugar and turns it into carbon dioxide and alcohol, to the point where there is so much alcohol, that it dies."

Cynthia helps keep the science of beer simple, while the wonders of science never cease.

"People have been making beer for thousands of years, and we've only known about microbes for a couple of hundred and that's just amazing to me that we're able to work with these little critters in such a way and make something that is so well loved." 

Karin Heineman is the executive producer of Inside Science TV. She has produced over 600 video news segments on science, technology, engineering and math in the past 14 years for Inside Science TV and its predecessor, Discoveries and Breakthroughs Inside Science. Reprinted with permission from Inside Science, an editorially independent news product of the American Institute of Physics, a nonprofit organization dedicated to advancing, promoting and serving the physical sciences.