Class IX Practical: Animal Life - Food Tests

Objective

To identify the presence of sugar, starch, protein, and fat in given food samples using appropriate biochemical tests.

Preparation: Prepare dilute solutions or suspensions of known samples (e.g., glucose solution, starch solution, egg albumin, oil) and unknown food samples.
Test Procedures: Follow standard protocols for each test:
- Sugar (Reducing Sugar): Benedict's test (heating required). Observe color change from blue to green, yellow, orange, or brick-red precipitate.
- Starch: Iodine test. Observe color change from yellowish-brown to blue-black.
- Protein: Biuret test. Observe color change from blue to violet/purple.
- Fat: Emulsion test (alcohol and water). Observe the formation of a milky white emulsion.
Observation: Carefully observe color changes, precipitate formation, or other indicators.
Recording: Create a table to record observations for both positive and negative controls, and for the unknown samples. Clearly state the inference for each test.

A clear understanding of the chemical basis of food tests and the ability to accurately identify major food components.

To identify the presence of sugar, starch, protein, and fat in given food samples using appropriate biochemical tests.

Preparation: Prepare dilute solutions or suspensions of known samples (e.g., glucose solution, starch solution, egg albumin, oil) and unknown food samples.
Test Procedures: Follow standard protocols for each test:
- Sugar (Reducing Sugar): Benedict's test (heating required). Observe color change from blue to green, yellow, orange, or brick-red precipitate.
- Starch: Iodine test. Observe color change from yellowish-brown to blue-black.
- Protein: Biuret test. Observe color change from blue to violet/purple.
- Fat: Emulsion test (alcohol and water). Observe the formation of a milky white emulsion.
Observation: Carefully observe color changes, precipitate formation, or other indicators.
Recording: Create a table to record observations for both positive and negative controls, and for the unknown samples. Clearly state the inference for each test.

A clear understanding of the chemical basis of food tests and the ability to accurately identify major food components.