EXPERIMENTAL BIOLOGY

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

• Starch is a reserve material of the plant, 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 adopt a blue-violet color.

DETECTION OF STARCHDIFFERENT PRODUCTS

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THE FIRST EXPERIMENT

In boiled rice, noodles, white cheese, bread, potato flour Lugol's solution color changed from orange to dark blue.

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

RESULTS

There is starch in boiled rice, noodles, white cheese, bread, flour. .

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

CONCLUSIONS

WHAT IS PROTEIN?

• Proteins are macromolecules 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 the condition and functioning of our body.

1) biuret reaction – a food product is treated by mixture VI cupric sulfate and potassium hydroxide in the presence of proteins which are stained purple; reakcja ta służy do wykrywania wiązań peptydowych

2) The xanthoproteic reaction - it is working on the product with concentrated nitric acid (V); this reaction finds application at the detection of proteins having aromatic nuclei

DETECTION OF PROTEIN

THE SECOND EXPERIMENT

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

RESULTS

There are some proteins in eggs.

CONCLUSIONS

Xanthoproteic Reaction

Fruits:

Kiwi

Banana

Apple

JoghurtMilk

In the reaction with the nitric acid (V):

- the milk and the yoghurt assumed the yellow colour

- the kiwi fruit, the banana and the apple didn't change the colour

RESULTS

1. Proteins with the aromatic structure were identified in dairy products

2. Fruit don't contain proteins or detecting them with this method is impossible, e.g. on account of the low sensitivity of the method or deficiency of proteins containing aromatic nuclei.

CONCLUSIONS

DETECTION OF FAT IN FOOD

METHOD

1. Grind the tested product in the paper napkin.

2. Check the napkin, holding it against the light. If there are grease stains, it means that food contains fat.

MATERIAL

Almonds

Walnut

Sunflower

Apple

RESULTS

walnutssunflower

RESULTS

applealmonds

The biggest grease stain appeared on the napkin after grinding seeds of sunflower. This fact suggests containing a lot of fat in this product. The apple did the wet stain on the napkin rather than fat what provides, that with this technique it is impossible to detect presence of fat.

RESULTS AND CONCLUSIONS