Theory What makes pop fizzy? It's the dissolved carbon dioxide in the drinks. One way of carbonating drinks is to use a micro-organism called yeast. Yeast are tiny single-celled, living plants. When placed in a warm, moist place and given sugar as a food source, the yeast become active and multiply. Meanwhile, they produce carbon dioxide gas as a metabolic waste product. Like in any living thing, the process of life for yeast involves metabolic processes that, by definition, produce waste. Just like in humans, the metabolic waste of yeast is carbon dioxide gas. This gas can make drinks fizzy or can make bread rise. If a drink that's being carbonated is placed in a sealed container, the space between the liquid and the cap fills up with carbon dioxide. As the concentration of carbon dioxide increases, the gas starts to get pushed into solution and the bubbles stay in the water. This makes the drink carbonated. If the cap was loose, the gas would escape and you would get "flat" pop. As long as the yeast have enough sugar to eat, they keep making carbon dioxide. Making Ginger Beer It is easy to make ginger beer at home in plastic soft drink bottles. This recipe makes about eight 1.5 L bottles of ginger beer. This type of yeast based drink will only keep about a week once it is ready. Ingredients: Equipment: 4 cups sugar 2 tablespoons ground ginger 2 teaspoons lemon essence 2 teaspoons tartaric acid 12 cups hot tap water 20 cups cold water 2 teaspoons dried yeast granules 10 L stock pot Ladel/stirring spoon Measuring cup, tablespoon, teaspoon 1.5 L plastic soda bottles Method: 1. 2. 3. 4. 5. 6. 7. 8. Mix the yeast with a few tablespoons of lukewarm water until smooth & leave it to stand until it is bubbly Measure the sugar, ginger, essence & tartaric acid into a clean stock pot/bucket Add the hot water & stir until the sugar is dissolved Add the cold water so that the solution is lukewarm Stir the yeast liquid into the rest of the liquid Pour into bottles using a funnel, leaving about 4-5 cm of air at the top Squeeze the bottle a little as you screw the lid on tightly Stand in a warm place for 4-7 days until there is sufficient ‘fizz’ & the bottles feel rigid (pressure has built up) 9. Chill the bottles for 1-2 hours before serving Bottom’s Up!
