STUDYING OF TECHNOLOGICAL PROPERTIES OF DYES AND FRAGRANCES

Materials: tubes alcohol lamp, tripods, raw materials and reagents.

 

The basis of natural dyes is constituted, as a rule, by pigments of plants which determine coloring of flowers, fruits, due to availability in them of carotinoids, flavonoids, a betanin, Riboflavinum, a chlorophyll, etc. connections. Fragrances, essential oils represent multicomponent mixes of organic compounds (aromatic, alicyclic and aliphatic carbonyl connections, alcohols, acids, air etc.) which in the course of obtaining, storages and uses in food products are exposed to oxidation by air oxygen. At the same time biological value decreases, organoleptic properties worsen and storage durations of food products decrease.

Experience No. 1. Selection of carotenoids and a betanin from root crops

Natural dyestuffs allocate in the physical ways (extraction, simple distillation, sublimation, etc.) from vegetable go animal sources: berries, flowers, leaves, root crops, etc., including a wastage at the canning and wine-making plants. Interest to the consumer is of b-Carotinum and бетанин which give to a product more attractive and natural look. The color range of b-Carotinum varies from light yellow to orange, a betanina - from pink to cherry.

Experimental technique: Crush pieces of carrots and beet of the size of a pea in a mortar and place in different test tubes with 10 drops of a tetrakhlrormetan, close a stopper and stir up during 20-30 sec. Note extragent decolourization.

Pour the received extract in three test tubes, then add several drops of substances: in the first – 10% solution of the hydrochloric acid, the second – 10% sodium hydroxide solution, a third – 1% potassium hypermanganate solution. Stir up test tubes and note changes.

Observations:

Conclusions:

Experience No. 2. Dependence of coloring of flavanols, flavanones, flavones from рН Wednesdays

Flavonoids differ on oxidation level or a saturation of a heterocyclic fragment, number and the relative position of hydroxyl groups among which there are flavanols, flavanones and flavones at restitution by a magnesium in the presence of the hydrochloric acid give the red or orange-red coloring caused by formation of antotsianidin.

Experimental technique: In a test tube flow 2 ml of solution of flavonoids (infusion of green tea, Rutinum, Quercetinum, etc.) add 5-7 drops of the hydrochloric acid and a small amount of a magnesium in the form of sawdust (or one granule of Zincum), then to heat solution, in 3-5 minutes observe coloring. Cast the received solution in other test tube and add several drops of 10% of solution of sodium hydroxide before decolourization.

Chemistry:

antotsianidin.

Rutinum (group of flavanols)

Anthocyanidin

Observations:

Conclusions:

Experience No. 3. Interaction of flavonoids with salts of metals

Flavonoids at disolution in hard water interact with cations of metals (iron, calcium, magnesium, etc.), at the same time variously painted settlings are formed. So, at interaction with lead acetate flavonoids form the settlings painted in yellow-orange, red or blue color.

Experimental technique: In a test tube flow 1 ml of solution of flavonoids (infusion of green tea or onion, Rutinum, Quercetinum, etc.), add 3-5 drops of 2% of solution of lead acetate. Observe breaking.

Chemistry:

Rutinum

Observations:

Conclusions:

Experience No. 4. Detection of catechols in infusion of green tea

Catechols contain in leaves of green tea, cocoa beans, apples, black grapes, barley grains. In technological process of receiving black tea there is an enzymatic oxidation of catechols which is followed by processes of intermolecular condensation (formation of the teaflavin defining yellow-orange coloring of solution).

The reference reaction to catechols is it is black - green coloring on reaction with iron chloride solution, is red - crimson - with vanillin solution in the hydrochloric acid.

Experimental technique: In two test tubes flow 1 ml of an aqueous solution of catechols (infusion of green tea), then to one test tube add 3-5 drops of 1% of solution of chloride of iron, to another - 3-5 drops of 1% of solution of vanillin in a concentrated hydrochloric acid.

catechol

Observations:

Conclusions:

Experience No. 5. Wet distillation of terpenes from fruits of a citrus

Naturalnyearomatizatora are taken in the physical ways (pressing, extraction, distillation) from starting materials of a vegetable or animal origin. They, in the majority are water-insoluble, well rastvorima in vegetable oils. The period of validity of an essential oil is strongly influenced by quantity of terpenes (a limonene, citral, a geraniol, etc.), the most easily oxidable compounds of oil.

Experimental technique. Crush a piece lemon or an orange-peel of 1 cm2 in size and place in the first test tube from 3 ml of water. Then insert into a test tube a colonic tube which end lower in other test tube placed in a glass with cold water. Carefully you boil liquid in the first test tube until in the second test tube 1-2 ml of colourless liquid gather (condensate), note its reference smell. Add to condensate several drops 1% of an aqueous solution of potassium hypermanganate, mix solution and note changes.

Observations:

Conclusions:

Experience No. 6. Receiving flavors identical to natural

Experimental technique. Bring carboxylic acids (1 ml) and alcohols (2 ml) in four test tubes, then add 10 drops of concentrated sulfuric acid, to heat mix to boiling. In several seconds there is a refreshing air smell:

a) acetic acid + isoamyl alcohol ®изоамилацетата (pear smell);

b) formic acid + ethanol ®этилформиата (rum smell);

c) acetic acid + benzalcohol ®бензилацетат (jasmine scent);

d) butyric acid + ethanol ®этилбутират (pineapple smell).

 

ethyl formosol benzyl acetate isoamyl acetate ethyl butyrate

Observations:

Conclusions:

Experience No. 7. Detection of peroxide compounds in terpenes and essential oils

As a part of a flavor only 10-20%, the others - solvents or carriers fall to the share of flavoring components. Needs to store the flavors incorporating the easily oxidized components (actually flavoring components or the carrier) in the dark place in densely the closed capacity at a temperature of 5 - 15 With, for prevention of oxidation by air oxygen. First of all unsaturated compounds are exposed to oxidation, at the same time nonresistant hydroperoxide compounds in  -situation in relation to an olefinic linkage which can be found on reaction with a potassium iodide are formed.

Experimental technique. To place in several test tubes on 1 drop 10% of solution of an iodide of a potassium and 5 drops of the studied substances: terpenes (turpentine, limonene, Mentholum, etc.), essential oil (dill oil, camphoric, turpentine, mint, etc.), carriers (oleinic acid, sunflower-seed oil, luccu oil, etc.). Aggressively stir up mix. The allocated iodine paints solution from straw-colored till brown color. If solution coloring poorly straw-colored (i.e. it is badly distinctive), then add to mix 1-2 drops 1% of solution of Amylum. In the presence of an iodine coloring of solution gains blue color.

Chemistry:

limonene a-hydroperoxide compound

Observations:

Conclusions:

 

Control questions

1. Why extraction by b-Carotinum from carrots is carried out by a tetrachlormethane, but not water?

2. What potassium hypermanganate solution decolorization observations at interaction by b-Carotinum testify to?

3. On the basis of the made experiment draw a conclusion on the relation of dyes to change рН solution.

4. Why it is impossible to dissolve natural dyestuffs in hard water?

5. What caused a volatility of terpenes with steam?

6. What structural component of terpenes provides potassium hypermanganate solution change? Write the reaction equation on the example of a limonene.

7. Write the equations of reactions of the corresponding reactions of receiving flavors.

8. What role is carried out by sulfuric acid in the given reactions?

 

LABORATORY WORK № 8

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