Beer preparation by fermentation involves picking rye, wheat or barley followed by germinating, drying and pulping it into a mash. The mash is mixed together with hot water and transferred to a fermentation vessel to commence the process of fermentation. Yeast is added to the mixture that converts the sugar present in the ash to carbon dioxide and alcohol. Once the beer is filtered and conditioned, it is ready for consumption (Boulton & Quain, 2008).The purpose of this experiment is to determine the rate of respiration by considering the amounts of CO2 produced in a cellular respiration by yeast. The experiment uses sucrose, dextrose, starch, glucose and distilled water as the food sources.The first procedure was the creation of hypothesis regarding the rate of fermentation for the four different substrates and recording them. Labelling of five small test tubes and five large test tubes with numbers 1-5 followed. The next step was filling the five small test tubes with the substrate solution to two-thirds full.Pasteur pipette aided in finishing filling the test tubes with a thoroughly mixed yeast solution. It was advisable to mix the yeast suspension immediately before adding it to the tubes and the filling of the tubes be as full as possible while holding them over a sink. The larger tube was inverted and placed over the smaller tube containing the yeast suspension and glucose. The use of a finger or a pencil aided in pushing the smaller tube all the way into the larger tube and then inverted both tubes so that the opening of the larger tube is up. Repetition of the same procedure followed for the other four tubes.The next step was placing the five test tubes in a 370c incubator and recording the time. The time at the start of the incubation was 7. It was crucial checking the tubes every five minutes to observe the size of the gas bubble that accumulates in the small tube. What followed next was stopping the experiment when the gas bubble in any of the tubes was approximately one-half of the length of the tube.
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