Question:
The specific gravity of amyl alcohol (Grade I) at 27$^\circ$ C to be used for fat estimation of milk by Gerber method as per BIS Method is:
The specific gravity of amyl alcohol (Grade I) at 27$^\circ$ C to be used for fat estimation of milk by Gerber method as per BIS Method is:
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Always run a blank test using distilled water instead of milk to verify the purity of the amyl alcohol.
If any oily layer separates at the top of the column during the blank run, the amyl alcohol is contaminated and must not be used for fat testing.
If any oily layer separates at the top of the column during the blank run, the amyl alcohol is contaminated and must not be used for fat testing.
Updated On: Jul 21, 2026
- 0.807 - 0.809
- 0.907 - 0.909
- 0.789 - 0.790
- 0.907 - 1.02
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
The Gerber method is a standard volumetric method used to estimate fat content in milk and milk products.
In this test, concentrated sulfuric acid is used to digest milk proteins, liberating the milk fat.
Amyl alcohol is added to facilitate the separation of fat from the aqueous phase and to obtain a clear, readable fat column.
The purity and physical characteristics of the reagents must strictly adhere to national standards (BIS) to avoid analytical errors.
Step 2: Detailed Explanation:
According to the Bureau of Indian Standards (BIS) specifications for Gerber-grade amyl alcohol (Grade I), physical parameters such as specific gravity are tightly regulated.
At the standard reference temperature of 27$^\circ$ C, the specific gravity of amyl alcohol (Grade I) must be within the range of 0.807 to 0.809.
Amyl alcohol used in this test must consist primarily of 3-methylbutan-1-ol with minor amounts of 2-methylbutan-1-ol.
If the specific gravity is too high or too low, it indicates contamination with impurities like water, lower alcohols, or higher-boiling fractions.
Impurities in amyl alcohol can lead to incorrect fat readings.
Specifically, these impurities can dissolve in the fat layer, falsely increasing the fat reading in the butyrometer.
Additionally, low-grade amyl alcohol can cause charring or a cloudy interface, making it difficult to read the meniscus.
Step 3: Final Answer:
The specific gravity of amyl alcohol (Grade I) at 27$^\circ$ C as per BIS Method is 0.807 - 0.809.
The Gerber method is a standard volumetric method used to estimate fat content in milk and milk products.
In this test, concentrated sulfuric acid is used to digest milk proteins, liberating the milk fat.
Amyl alcohol is added to facilitate the separation of fat from the aqueous phase and to obtain a clear, readable fat column.
The purity and physical characteristics of the reagents must strictly adhere to national standards (BIS) to avoid analytical errors.
Step 2: Detailed Explanation:
According to the Bureau of Indian Standards (BIS) specifications for Gerber-grade amyl alcohol (Grade I), physical parameters such as specific gravity are tightly regulated.
At the standard reference temperature of 27$^\circ$ C, the specific gravity of amyl alcohol (Grade I) must be within the range of 0.807 to 0.809.
Amyl alcohol used in this test must consist primarily of 3-methylbutan-1-ol with minor amounts of 2-methylbutan-1-ol.
If the specific gravity is too high or too low, it indicates contamination with impurities like water, lower alcohols, or higher-boiling fractions.
Impurities in amyl alcohol can lead to incorrect fat readings.
Specifically, these impurities can dissolve in the fat layer, falsely increasing the fat reading in the butyrometer.
Additionally, low-grade amyl alcohol can cause charring or a cloudy interface, making it difficult to read the meniscus.
Step 3: Final Answer:
The specific gravity of amyl alcohol (Grade I) at 27$^\circ$ C as per BIS Method is 0.807 - 0.809.
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