How Fermentation Works

Hi I'm Dr. Kiki Sanford and today on Food Science, we are talking about fermentation. Strictly speaking, fermentation is an energy producing process that does not require oxygen to take place. It’s anaerobic in nature. Bacteria, yeast, and even human cells use fermentation to create energy in the form of ATP from sugar. Some organisms like the bacteria that can get into canned food and cause botulism or that lives in rust and can cause tetanus will die if they’re exposed to oxygen. They rely on fermentation for all their energy. Others use oxygen that can switch to fermentation if the environment demands it. Still others don’t really care one way or another so to break it down. Cells take the simple sugar glucose and split it into a compound called pyruvate through a process called glycolysis then depending on the organism the pyruvate can go down one of two different fermentation pathways. In human muscle cells and on the bacteria that help us make yogurt, pyruvate gets converted in the lactate. You might call it lactic acid. Thank you little bacteria. [Cough] Yum! The other pathway is used by single-celled organisms to convert the pyruvate into carbon dioxide and alcohol. Some of the animals have been taking advantage of for a long time. Eat the little berries, get a little junk, I’m a little birdie and I'm going to land on a trunk. Humans have harnessed the fermenting power of Saccharomyces cerevisiae, a type of yeast for bread making. The yeast ferments the sugar added to the doe creating carbon dioxide which makes the bread rise by creating lots and lots of bubbles. The gas is forced out of the bread but the spaces left behind by the air bubbles give us the fluffy porous final product. We can take advantage of yeast sugar addiction for more kitchen fun like making carbonated ginger ale because that’s what you would do right? That’s what I did. So first with the funnel and the 2 litre bottle, we’re going to take a cup of white sugar and a quarter teaspoon of yeast. Use bread making yeast that you can get at a grocery store. It’s convenient and it works just fine. Take your funnel out and shake it to distribute the yeast throughout the sugar. Now we’re going to grate 1-1 ½ tablespoons of fresh ginger. Add more ginger if you like it spicier. Take the ginger and just stuff it in your bottle then add the juice of one lemon. Meyer lemons work great because they’re very sweet but you know whatever lemon will work. Squeeze that and then it gets it to do it again. Be strong to work these things. Squeeze, squeeze, squeeze and there we go. Add that to the mix in the bottle and shake it again and mix that stuff up. Put the funnel back in, and then fill the bottle almost to the top with water. Cap it and shape it again. This time, give it a really vigorous shaking and then you’re almost full that was the silly song. When you’re done shaking it, put it on some place warm not hot for 24- 48 hours. The yeast will do its thing, take out the sugar and convert in to carbon dioxide and a little bit of alcohol but not so much that you need to worry about getting buzzed. However, you do need to be concerned with how much CO2 is being formed too much and you might end up with an exploding soda bottle so check it periodically by squeezing it with your fingers when you can no longer dent the bottle, it’s done. Stick it in the fridge to chill. The cool temperatures will slow down the yeast metabolism and the fermentation process keeping you from having to clean up a giant mess. When it’s sufficiently chilled, strain out the ginger and drink. Umm tangy But remember, it’s not just food. It’s science, science, science. It’s not just food science. It’s science, science, science. All original shows are all on HD from anetworks.com