EXPERIMENTAL BIOLOGY

• Starch is a white, amorphous substance, tasteless, insoluble in cold water and ethanol.

• Starch is a reserve material of the plant, which is mainly in the seeds.

• Starch as a reserve material is also stored in the fruit and storage organs.

• Starch is used in the textile, cosmetic, pharmaceutical, spirits.

WHAT IS STARCH?

Starch can be detected by means of iodine or Lugol's solution, which contains iodine.

Under the influence of iodine starch adopts a violet-blue colour.

DETECTION OF STARCHIN DIFFERENT PRODUCTS

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THE FIRST EXPERIMENT

In boiled rice, noodles, white cheese, bread, potato flour the colour of Lugol's solution changed from orange into dark blue.

In washing powder, white soap and white material lugol's solution didn’t change its colour.

RESULTS

Starch is present in boiled rice, noodles, white cheese, bread and flour. .

There is no starch in washing powder, white soap and white material.

CONCLUSIONS

WHAT IS PROTEIN?

• Proteins are macromolecules which are composed of amino acids.

• Proteins are the basic building blocks of all tissues of the human body, and many compounds such as

enzymes, hormones, antibodies.

• Proteins regulate metabolism and many body functions, ensuring correct condition and functioning of our body.

1) biuret reaction – a food product is treated by a mixture of cupric sulfate (VI) and potassium hydroxide in the presence of proteins which are stained purple; this reaction is used for a detection of peptide bonds

2) Xanthoproteic reaction- using concentrated nitric acid (V); this reaction can be found at detection of proteins having aromatic nuclei.

DETECTION OF PROTEINS

THE SECOND EXPERIMENT

In biuret reaction tested product changed its colour from blue into purple.

RESULTS

There are some proteins in eggs.

CONCLUSIONS

Xanthoproteic reaction

Fruits:

Kiwi

Banana

Apple

JoghurtMilk

In the reaction with the nitric acid (V): - Milk and joghurt changed colour into yellow.

- kiwi, banana and apple didn’t change its colour.

RESULTS

1. Dairy products contain proteins with aromatic structure.

2. Fruits do not contain proteins or their detection with this method is impossible due to the low sensitivity of the method or deficiency of proteins containing aromatic nuclei.

CONCLUSIONS

DETECTION OF FATS IN THE FOOD

METHOD

1. Grind the tested product in the paper napkin.

2. Examine the napkin holding it against the light. If fat stains are present, it means that food contains fat.

MATERIALS

Almonds

Walnut

Sunflower

Apple

RESULTS

walnutssunflower

RESULTS

applealmonds

The biggest stain of fat was noticed on the napkin with sunflower seeds. It means that this product is the richest in fats. The apple left wet stain on the napkin. With the use of this method, fats were not detected in the fruit.

RESULTS AND CONCLUSIONS

Thank you for your attention