Presentation on chemistry on the topic "starch". Presentation on the topic "starch" Presentation on the topic corn starch

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In rice - 80%

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Wheat and corn-70%

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Receipt

Starch is most often obtained from potatoes. To do this, the potatoes are crushed, washed with water and pumped into large vessels where settling occurs. The resulting starch is washed again with water, settled and dried in a stream warm air

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Physical properties

It occurs in the form of white grains. Starch grains are insoluble in cold water;

In hot water, the membrane of the grains bursts and the starch forms a colloidal solution (gel).

Does not have a sweet taste.

Slide 8 Chemical properties

Qualitative reaction to starch. Iodine forms a complex compound with starch intensively

of blue color

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Experience “Qualitative reaction”

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Hydrolysis

Reaction equation: (C6H10O5)n + nH2O → nC6H12O6 Stepwise hydrolysis Starch dextrins maltose glucose

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Destruction by heating

When starch is heated, macromolecules are destroyed with the formation of compounds with a lower molecular weight - dextrins. Due to partial dehydration, dextrins acquire a yellow and golden-brown color. This process occurs when baking flour confectionery products, since starch makes up the main part of wheat flour.

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Experiment “Acid hydrolysis of starch”

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Application in the paper industry

Corn starch is used for roll sizing and surface sizing in the paper industry. This increases the paper strength, lays down surface lint and increases the stiffness and rattle of the document.

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Application in confectionery and bakery production

Corn starch is widely used in the food industry as a thickener for sauces, puddings and pie fillings. In bakeries, it helps soften wheat flour and provides good texture.

Cornstarch is easily converted into a smooth paste within an hour when pressure cooked. This makes its use in the textile industry widely popular. Its viscosity ensures uniform flow and penetration into the interstices of the yam, which ensures a good weave of the thread.

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Construction Application

For the production of building mixtures, thickeners and binders based on corn starch are used. Starch-based additives are being developed for the construction industry. They are used to impart specific properties cement mortars, plaster mortars, gypsum products, finishing mixtures, etc.

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Application of Pharmaceutical Industry

Cornstarch is best suited as vehicle for compressing tablets in the pharmaceutical industry.

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Research student 2 "A" class MBOU "OOSH" No. 7 Bondarenko Danila

Mysterious starch and its significance for humans

Head: Belozerova Natalya Nikolaevna

Goal of the work:

• Find out what effect foods containing starch have on our health.

2. Determine what foods adults and children like to eat: with or without starch.

Z adachi:

1. Study information about starch.

2. Study methods for detecting starch in food.

3. Conduct a survey among adults and children about their favorite foods.

4. Conduct an experiment to determine the presence of starch in food products, based on survey data.

5. Analyze the survey results.

6. Study the areas of application of starch.

Object of study: starch

Subject of study: Food

Research methods: literature study, experiments, surveys, observations

HYPOTHESIS.

If we study starch, we will learn about the benefits or harms of starch and this can allow us to create the right diet.

What is starch?

STARCH - the main reserve carbohydrate of plants is formed in their cells and accumulates mainly in seeds, bulbs and tubers, as well as in leaves and stems.

Properties of starch.

• Tasteless white powder, insoluble in cold water.
• IN in his hand he makes a “creaking” noise caused by the friction of particles.

• It swells (dissolves) in hot water, forming a viscous solution - a paste;

• WITH solution of iodine forms a compound that has blue color.

The role of starch in human nutrition .

Starch is a carbohydrate, one of the main sources of energy for humans.

Conclusions:

1. Starch is beneficial because it quickly replenishes a person’s energy.

But its excess can cause harm - overweight, obesity, obesity.

2. Nutrition should be balanced

EXPERIMENTS

To study properties starch I chose potato starch.

Hypothesis: starch creaks

Experience 1: I poured starch into a cup. I rubbed it between my fingers: indeed, a slight creak was heard

Hypothesis: starch does not dissolve in cold water, turns into a glue-like mass

Experience 2: He poured water into a glass and mixed water with starch. Starch did not dissolve in water. While stirring, a viscous mixture formed at the bottom of the glass. On it felt sticky to the touch.

starch reacts with iodine to give a blue or purple tint.

Experience 3: For this I took: a napkin, iodine, dry starch, starch mixed with water.

Dropped a few drops of iodine onto a napkin, into dry starch and starch mixed with water

• Iodine on a brown napkin.

• When reacting with dry starch, iodine turns dark purple.
• If iodine is added to starch mixed with water, we see that it turns dark blue.

Conclusion: All hypotheses about the properties of starch were confirmed

Survey .

We conducted a survey among children and adults about what foods they like most.

Adults were also asked the question: “What do you know about starch?”

Participated in the survey: students of class 2 “A” of our school – 30 people, teachers primary school, my grandmother and colleagues from my mother’s work - 15 people.

We received the following survey results:

Five most popular food products .

Children

1 . apple 11 people

2 . banana 11 people

3 . tangerine 6 people

4 . chicken/meat 5 people

5 . milk 4 people

Adults

1 . potatoes 6 people

2 . fish 4 people

3 . meat 4 people

4 . yogurt 3 people

5 . fruits 3 people

The following products were selected for testing for the presence of starch:

7 . fish

8 . yogurt

1 . apple

2 . banana

3 . mandarin

4 . chicken

5 . milk

6 . potato

9 . cabbage

10 . tomato

11 . baked goods (bread, cookies)

Cabbage, tomato and pastries were selected additionally from the survey, they scored equal votes with fruit and yogurt

The products were divided into groups:

• Vegetable origin
• Animal origin
• Mixed

Animal products

Mixed group:

P Origin:

Vegetable products

origin:

11 . bread

12 . cookie

1 . apple

2 . banana

3 . mandarin

4 . potato

5 . cabbage

6 . tomato

7 . chicken

8 . milk

9 . Yogurt

10 . fish

Experience 4 : checked the presence of starch in food products of plant origin

Each product was placed in a separate cup and iodine was dropped onto it.

Overripe banana

Mandarin

Unripe banana

Apple

Potato

Tomato

Cabbage

We got the following results:

No starch :

• . in an apple
• . in an overripe banana
• . in mandarin
• . in cabbage
• . in tomato

Starch is:

1. in an unripe banana

2. in potatoes

Conclusions:

• Not all plants contain starch
• As some foods ripen, starch may disappear from them.

We turned to the Internet, the Medical Information Network site, and learned that as bananas ripen, the starch turns into sugar. Therefore, ripe bananas are sweeter.

Experience 5: checked the presence of starch in foods of animal origin

Each product was placed in a separate cup and iodine was dropped onto it.

Milk

Yogurt

Chicken

Conclusions: animal products do not contain starch

Fish

Experience 6: Checked for starch in mixed foods

Each product was placed in a separate cup and iodine was dropped onto it.

Cookie

Bread

The composition of cookies and bread includes products of plant origin: wheat (wheat flour) and animal - butter or margarine.

Wheat contains starch, and margarine or butter contains animal fat

Conclusion: in mixed products, starch does not disappear anywhere.

Analysis of survey results .

When surveying children, it became clear that the majority like: apples and bananas.

We know that most children love ripe bananas. This means that the starch content in them is minimal. Other products also do not contain starch

When interviewing adults It became clear that most people love potatoes. In second and third place are fish and meat.

From experience, potatoes contain a lot of starch. Fish and meat and other products do not contain starch.

Conclusions:

1. Most students in class 2 “A” prefer foods that do not contain starch.

2. Most adults prefer mixed foods.

Other uses of starch

From the adult survey I also learned:

1. Starch can be useful in everyday life: it used to be used to treat shirt collars. This made them appear whiter. And since starch hardens when it dries, the collars held the shape they were given. Napkins and tablecloths were starched for this purpose.

2. Starch was used by artists: previously, canvases for painting were treated with starch so that paints would not leak through them.

3. Nowadays, starch is used in the manufacture of: tablets, ointments and powders, and also

in the production of paper, cardboard, paints, glue. And I was surprised when I learned that starch is used in the manufacture of sausages and sausages.

Conclusion .

1. Starch can bring both benefit and harm to humans.

2. It is important to eat right, consume foods that contain starch in moderation, but you cannot avoid them, a person needs them.

3. I found out that students in our class prefer foods without starch. And adults love mixed foods.

Adults need to monitor their children’s nutrition so that they replenish energy on time and sufficiently. Since without adult supervision, most of the students in our class will eat only fruits on their own, and this is not enough for their healthy development .

Starch can be found in food products: pasta, vermicelli, bread, pancakes, flour products, jelly, porridge

And also to grow properly and keep your weight normal – you need to play sports!

Thank you for your attention.

Be healthy!

Description of the presentation by individual slides:

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Starch consists of 2 polysaccharides - amylose and amylopectin, formed by glucose residues. It has been experimentally proven that the chemical formula of starch is (C6H10O5)n. It has been established that starch consists not only of linear molecules, but also of molecules with a branched structure. This explains the granular structure of starch. Accumulates in the form of grains, mainly in the cells of seeds, bulbs, tubers, as well as in leaves and stems. Starch is a white powder, insoluble in cold water. In hot water it swells and forms a paste. The structure of starch.

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Physical Properties Tasteless, amorphous white powder, insoluble in cold water; in hot water it swells (dissolves), forming a colloidal solution - a paste. Under a microscope it can be seen that it is a granular powder; When starch powder is squeezed in your hand, it produces a characteristic “crunch” caused by the friction of the particles.

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chemical properties It swells in hot water, in water and with the addition of acid (H2SO4, diluted, etc.) as a catalyst, it gradually hydrolyzes with a decrease in molecular weight, down to glucose. Forms a colloidal solution (starch paste); with iodine solution gives a blue color. Starch molecules are heterogeneous in size. Starch is a mixture of linear and branched macromolecules. Under the action of enzymes or heating with acids, it undergoes hydrolysis. Equation: (C6H10O5)n + nH2O-H2SO4→ nC6H12O6. Qualitative reactions: Starch, unlike glucose, does not give a silver mirror reaction. Like sucrose, it does not reduce copper(II) hydroxide. Interaction with iodine (blue color).

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Nutritional value In the gastrointestinal tract of humans and animals, starch is hydrolyzed and converted into glucose, which is absorbed by the body. Starch, as a food additive, is used to thicken many foods, prepare jelly, dressings and sauces.

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Biological properties Starch, being one of the products of photosynthesis, is widespread in nature. For plants, it is a supply of nutrients and is found mainly in fruits, seeds and tubers. The grains of cereal plants are the richest in starch: rice (up to 86%), wheat (up to 75%), corn (up to 72%), and potato tubers (up to 24%).

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For the human body, starch, along with sucrose, serves as the main supplier of carbohydrates - one of the most important components of food. Under the action of enzymes, starch is hydrolyzed to glucose, which is oxidized in cells to carbon dioxide and water, releasing the energy necessary for the functioning of a living organism.

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Modification of starch In industry, the conversion of starch into glucose (saccharification process) occurs by boiling it for several hours with dilute sulfuric acid (the catalytic effect of sulfuric acid on the saccharification of starch was discovered in 1811 by K. S. Kirchhoff). To remove sulfuric acid from the resulting solution, chalk is added to it, producing insoluble calcium sulfate from sulfuric acid. The latter is filtered off and the substance is evaporated. The result is a thick sweet mass - starch syrup, which contains, in addition to glucose, a significant amount of other starch hydrolysis products. Molasses is used for the preparation of confectionery products and for a variety of technical purposes. If you need to get pure glucose, then boiling the starch takes longer than it is more completely converted into glucose. The solution obtained after neutralization and filtration is concentrated until glucose crystals begin to fall out of it. Also, currently, starch hydrolysis is carried out enzymatically, using alpha-amylase to produce dextrins of various lengths, and glucoamylase for their further hydrolysis to produce glucose.

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When dry starch is heated to 200-250°C, its partial decomposition occurs and a mixture of polysaccharides (dextrin and others) that are less complex than starch is obtained. The physical change produces starch with a high moisture-holding capacity, which in turn gives the final product the desired consistency. Modified starch has nothing to do with genetically modified organisms, since it is not changed at the genetic level. Modified starch

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Application of starch. Starch is the main part of the most important food products: flour (75 - 80%), potatoes (25%), sago, etc. Energy value is about 16.8 kJ/g. It is a valuable nutritious product. To facilitate its absorption, starch-containing foods are exposed to high temperatures, that is, potatoes are boiled, bread is baked. Under these conditions, partial hydrolysis of starch occurs and dextrins, soluble in water, are formed. Dextrins in the digestive tract undergo further hydrolysis to glucose, which is absorbed by the body. Excess glucose is converted into glycogen (animal starch). The composition of glycogen is the same as that of starch - (C6H10O5)n, but its molecules are more branched. The liver contains especially a lot of glycogen (up to 10%). In the body, glycogen is a reserve substance that is converted into glucose as it is consumed in cells. In industry, starch is converted into molasses and glucose by hydrolysis. To do this, it is heated with dilute sulfuric acid, the excess of which is then neutralized with chalk.

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The resulting precipitate of calcium sulfate is filtered off, the solution is evaporated and glucose is isolated. If starch hydrolysis is not completed, a mixture of dextrins and glucose is formed - molasses, which is used in the confectionery industry. Dextrins obtained from starch are used as glue to thicken paints when applying designs to fabric. Starch is used for starching linen. Under a hot iron, starch is partially hydrolyzed and converted into dextrins. The latter form a dense film on the fabric, which adds shine to the fabric and protects it from soiling. Starch and its derivatives are also used in the production of paper, textiles, foundries and other industries, as well as in the pharmaceutical industry.