The most common substrate used in distilleries for the production of ethanol is

Options

A. Corn meal
B. Soya meal
C. Ground gram
D. Molasses

Answer

**Step-by-Step Solution:**

1. **Understanding Ethanol Production**: Ethanol is produced in distilleries primarily through a process called fermentation. This process involves the conversion of sugars into ethanol and carbon dioxide by microorganisms, particularly yeast.

2. **Identifying the Microorganism**: The yeast commonly used for ethanol production is *Saccharomyces cerevisiae*. This microorganism plays a crucial role in catalyzing the fermentation process.

3. **Recognizing Substrates**: The substrates for ethanol production can be categorized into three major types:
- Sugars
- Starch
- Cellulosic materials

4. **Sources of Substrates**:
- **Sugars**: Direct sources include sugarcane pulp, sugar beets, and molasses. These can be used directly in fermentation.
- **Starch**: This is obtained from grains, potatoes, and root crops. However, starch must first be hydrolyzed into sugars before it can be fermented.
- **Cellulosic Materials**: These can also be converted into sugars through hydrolysis, but they are not as commonly used in distilleries.

5. **Evaluating the Options**:
- **Cornmeal**: This is primarily a starch source and does not directly provide sugars, making it an incorrect option.
- **Soya Meal**: This is rich in proteins and is not suitable for ethanol production, hence incorrect.
- **Ground Gram**: Similar to the above, it is not a primary substrate for ethanol production, so it is incorrect.
- **Molasses**: This is a byproduct of sugar production and is rich in sugars, making it an ideal substrate for ethanol fermentation.

6. **Conclusion**: Based on the analysis, the most common substrate used in distilleries for the production of ethanol is **molasses**.

**Final Answer**: Molasses

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