P5. Saccharides properties

Introduction:

Today we will learn to differentiate monosaccharides, disaccharides and starch from its taste, if color, solubility and test lugol are crystalline or not. Performing these tests can know how is glucose, a malty, one sucrose, lactose and starch one.

Objectives:

• Identify different sugars from its properties.
• Differentiate mono and disaccharides
• Understand the relation between structure and some properties.

Hypothesis:

• All monosaccharides are crystalline, all monosaccharides and disaccharides are water soluble and are transparent, however, polysaccharides (starch) are not soluble nor transparent. Lugol test only stain the starch.

Materials:

1. Test tube rack
2. 10mL pipet
3. Water
4. 5 test tubes
5. 1 dropper
6. 5 spatula
7. Lactose
8. Maltose
9. Glucose
10. Sucrose
11. Starch
12. Lugol's iodine
13. Distilled water

Procedure:

• Take glucose, maltose, sucrose, lactose and starch. First put into test tubes 5 5 mL of distilled water and add solutes (G, M, SU, L, S) in each of the tubes. We look at whether or not they are sweet, tastings. Then take a microscope and observe whether or not crystallize. Let us have the color (white or creamy). If you are soluble or not. As nem doing this, we are pointing in the results table.
• Once we arrive at the test Lugol, add two drops of Lugol's iodine and heat. If changes coor (a black-purple) means it is starch. Lugol test only identifies the starch.

Comments:

• All polysaccharides are NOT sweet
• All NON-soluble polysaccharides

Conclusions:

• 
  

Questions:

1.- Write the empirical formula of each saccharide that you have use. Show structures of the five     saccharides. Classify each one in one group: mono, oligo or polysaccharide.

        Glucose: C6H12O6 / monosaccharide.

        Maltose: C12H22O11 / oligosaccharide.

        Sucrose: C12H22O11 / oligosaccharide.

        Lactose: C12H22O11 /oligosaccharide.

        Starch: C6H10O5 / polisaccharide.

2.- Which of the monosaccharides are aldoses and which are ketoses?

       Aldoses: glucose, maltose, lactose, starch.

       Cetoses: sucrose.

3.- Which bond links monosaccharides?

       Oligosaccharides.

4.- Which saccharide/s is/are sweet? Is this property related to the structure of the molecule?

        Glucose,sucrose, maltose.

5.- Which saccharide/s is/are soluble? Is this property related to the structure of the molecule?

        Starch, because is a big molecule. (Pes molecular gran)

6.- Which saccharide has reacted with Lugol's iodine solution?

        Starch

7.- Which kind of foods contains starch?

        Cereals, pasta, rice, legums...                             

8.- Calculate the energy from the nutrition facts labelfrom a cereal

• Calculate the energy that comes from the saccharides.

              23x4,2= 96.6Kcal