Question

Comparative study of the rate of fermentation of the following materials.
Rice flour, gram flour and potato.

Answer 1

Hint:
Fermentation is known to cause the breaking down or oxidation of a substrate to alcohol using fungus. In general, the more the starch or carbohydrate that is present in the substrate the longer it takes for it to be converted into alcohols. Therefore, for this question we must gauge the different levels of carbohydrates that are present in the given substrate.

Complete step by step answer:
Different substrates give the same product that is alcohol but each substrate requires a different time period to be converted into alcohols.
As mentioned before, fungi like yeast are known to cause fermentation of many substances in the absence of oxygen. The concentration of carbon dioxide allowed is also restricted. Fermentation only occurs in the conditions that contain only $14\% $ carbon dioxide. If the level is any higher the yeast will become dormant and the fermentation will not take place.
Now that we know the conditions let us try to understand which substrate has the most carbohydrate level. To find this out we must perform an experiment.
The first step is to take equal amounts from the substrate to be a sample. On doing this we must take each sample one by one and allow it to ferment by adding a fermenting agent. On adding this, we can use the iodine test to see if there is any carbohydrate remaining in the sample.
The iodine test is a test for carbohydrates where if after the addition of iodine, the sample turns purple then it means that the sample still contains starch or carbohydrate.
 Repeat the test until there is no purple colour formed.
This process has to be repeated for each sample.
The results are as follows:
The rice flour took $15$ hours to ferment, gram flour took $12.5$ hours and finally potato took $13$ hours to ferment. This means that the rice flour took the most time to ferment and the gram flour took the least.

Note:The results of the above experiments indicates that the rice flour has the most carbohydrate or substrate ready to be fermented to form alcohol. Potato took two hours less to ferment and finally gram flour took the least time meaning that it has the least carbohydrate content.
-Remember that all fermentation reactions occur in anaerobic conditions.