Hello everybody, and welcome to a new season of Ithaca Bites, the Red Letter Daze food column. Every week, I’ll discuss a different dish or ingredient, from the humdrum to the exotic, with a little bit of science thrown in for flavoring.

As the fall semester roars into gear and leaves things like relaxation and sunshine in the dust, the average Cornell student’s diet becomes much less dependent upon picnic staples like watermelon and hamburgers as beer consumption returns to its nine-month plateau.

Still, each swig of Keystone and Pabst Blue Ribbon has a key ingredient in common with those fluffy hamburger buns, and that is a nifty little creature called a yeast.

Yeast is, on its most basic level, a single-celled fungus. I know, I know, you don’t like mushrooms and the idea of little things swimming in your alcohol only makes you feel nauseated. But in all honesty, yeast is an important part of just about every culture, either in the form of bread or alcoholic beverages.

It can even be a food in its own right, in the form of nutritional yeast or marmite.

In bread-making, a bit of sugar is added to the dough, which baker’s yeast is expert at metabolizing into carbon dioxide.

The process of “activating” yeast in warm water is really just hydrating the little yeast cells and getting them to start munching on the sugar in the bread dough. As the dough rises in a warm place, the yeast is multiplying and churning out carbon dioxide at a maddening rate, but as soon as the bread starts to bake they succumb to the heat and die off like hope in prelim season.

I had marmite for the first time my freshman year as a part of Dr. George Hudler’s famed “Magical Mushrooms, Mischievous Molds” class. I took a gob of the mysterious tar-like substance, thicker than molasses and about the same color, and spread it onto a saltine cracker.

Immediately, I was overwhelmed by a saltiness and bitter bullion tang that brought tears to my eyes. It was not explicitly bad, but I imagine that it would be difficult to truly love without growing up with it.

Marmite (and its kiwi cousin, Vegemite) is made primarily from the yeast bodies left over from the beer making process, and it packs a walloping B-vitamin complex. Nutritional yeast, marmite’s dry, flaky relative, is also rich in B-vitamins and protein, and is considerably more palatable to newcomers. I was introduced to nutritional yeast by a self-labeled hippie friend who makes popcorn with parmesan cheese, olive oil, salt, pepper and nutritional yeast — one of the rare snacks that is both healthy and yummy.

Perhaps the yeast’s most important function to the college crowd is its ability to metabolize sugars and complex carbohydrates to make alcohol and carbon dioxide.

This process takes some time, which is why beer, wine and the like are left to ferment for a while before they are bottled.

In the case of beer, a very specific and often secret recipe of grains, hops, sugar and yeast is added to clean water and left to ferment; wine instead uses natural yeast left on the skin of grapes to get started with the fermentation process.

Since alcohol is a waste product for yeast, they can only continue to reproduce to a certain local alcohol content before dying off; the naturally-occurring yeast on grape skins can handle around five percent alcohol by volume.

Certain species of yeast that have higher tolerances are used in both wine and beer-making in an effort to increase the alcohol content, but these max out around 12 percent by volume — for the record, higher-alcohol beverages are created via distillation.

You can observe the power of yeast (and some cool chemistry) at home by brewing your own ginger beer. Take a clean, empty 2-liter plastic bottle and fill it with two tablespoons of grated fresh ginger, one cup of sugar, the juice of two lemons, a quarter of a teaspoon of regular old baker’s yeast, and fill the bottle to the top with skin-temperature water.

Leave the bottle in a dark, room temperature place for 36 hours or until the bottle is hard to a forceful push, and then chill it in the refrigerator for 24 hours.

Voila!

You have made your very own soft drink (sorry guys, you’d have to drink gallons of this for a buzz), and one that gives a roundhouse kick to the face of ginger ale.