01. Food Tests

Test for reducing sugars

• 00:51 What is the colour of the mixture at the start?
• 01:06 What do you observe in the tube after heating for 5 minutes?

Test for non-reducing sugars

• 01:10 What is the colour of the mixture at the start?
• 01:26 What do you observe in the tube after heating for 5 minutes?
• 01:28 Why do you add dilute hydrochloric acid to the non-reducing sugar and heat it?
• 01:44 Why do you then add dilute sodium hydroxide or sodium bicarbonate?
• 01:51 What do you observe?
• 01:58 Can you explain why the Benedict’s test was negative at first, and then positive after adding acid, heating and adding alkali?

Test for protein

• 02:06 What colour is Biuret reagent at the start?
• 02:23 What colour is the solution after adding Biuret reagent?

Test for starch

• 02:26 What colour is iodine-potassium iodide solution at the start?
• 02:35 What colour is iodine-potassium iodide solution in the presence of starch?

Test for fats and oils

• 02:46 What do you observe where the alcohol and oil meet?

• 5 boiling tubes

• 2 test tubes

• 1 beaker

• 3 dropping pipettes

• Benedict's reagent

• dilute hydrochloric acid (0.5 moldm^-3)

• dilute sodium hydroxide solution/sodium bicarbonate

• Biuret reagent

• iodine-potassium iodide solution

• absolute alcohol

• glucose solution

• sucrose solution

• albumen solution

• starch solution

• oil

• water bath