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.

Guidelines

1. Preparation: Prepare dilute solutions or suspensions of known samples (e.g., glucose solution, starch solution, egg albumin, oil) and unknown food samples.
2. 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.
3. Observation: Carefully observe color changes, precipitate formation, or other indicators.
4. 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.

Expected Outcome

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