Protocol for Practical Classes

Subject: Carbohydrates

Experiment 5 – Starch - extration

Materials:

Provided by the students

1 potato and a knife

Filter paper or gauze

From the laboratory

Mixer

2 bequers ( 1 e 2 ) - 200 mL

Boiling water and cold water

A pippete

Metods:

Mix the potate (no rind) with 100mL de distilled water (standard temperature) and transfer it to the bequer 1, without disdaining the formed liquid.

Filtrar o material tranfering it to the bequer 2.

Leave bequer 2 in rest for 10 minutes and notice that a white pellet is forming.

Clean bequer 1.

Boil 150 mL of distilled water on it.

Carefully separate the upper part of the bequer 2 content.

To the pellet, add 50ml of cold water, agitate and mix to the water in bequer 1 untill the formation of and opac solution (keep it for latter experiments).

Objectives:

To caractherize the starch structure and its storage form on the cells.

To identify the influence of both on its solubilization and also the effect of the temperature.

Report suggestions:

Explain the reasons why the starch either precipates or solubilizates according to the temperature of the water.

Link this property to the starch structure.

Explain how other carbohydrates shoul behave.