3. • 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?
4. 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 STARCH
IN DIFFERENT PRODUCTS
c
6. 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
7. 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
8.
9. 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.
10. 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
15. 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
16. 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
19. 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.
23. 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
