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 The process by which green plants use energy from the sun to change carbon dioxide and water into glucose and oxygen.  Carbon dioxide + Water → Glucose + Oxygen.  6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2 2

There are 3 types of carbohydrates 1. Monosaccharides 2. Disaccharides 3. Polysaccharides 3

CH 2 OH C H OH H O C C C C H OH H OH H OH 4

 A Monosaccharide contains one sugar unit  C 6 H 12 O 6 is the chemical formula of a monosaccharide  Glucose, fructose and galactose are the 3 monosaccharides 5

 Are formed when two mono saccharides join together with the elimination of water (condensation)  There are three disaccharides: maltose, sucrose & lactose  The chemical formula is C 12 H 22 O 11 C 6 H 12 O 6 +C 6 H 12 O 6 C 12 H 24 O 12 - H 2 O C 12 H 22 O 11 6

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 These are formed when three or more monosaccharides join together with a loss of a water molecule each time.  They may be straight or branched  Examples: Starch, pectin, cellulose, gums & glycogen  Pectin, cellulose & gums are also known as Non-Starch Polysaccharides  Starch is made up of glucose units arranged as follows: 1. Straight chains are known as amylose or 2. Branched chains are known as amylopectin 8

 Formula: (C 6 H 10 O 5 )n C 6 H 12 O 6 - H 2 O (C 6 H 10 O 5 )n n=the number of times a bond is formed Chemical structure of a polysaccharide 9

ClassChemical Formula ExampleSource Monosaccharides C 6 H 12 O 6 Glucose Fructose Galactose Fruit Honey Digested milk Disaccharides C 12 H 22 O 11 Maltose= Glucose+Glucose Sucrose= Glucose+Fructose Lactose= Glucose+Galactose Barley Table sugar Milk Polysaccharides (Complex Carbs) (C 6 H 10 O 5 ) n Starch Cellulose non-starch Pectin polysaccharides Glycogen Bread, pasta Whole cereals Fruit cell wall Liver and muscle cells 10

 These are also known as NSPs, dietary fibre and roughage  NSPs cannot be digested in the body and absorb large amounts of water  They aid the removal of waste from the body by a process known as peristalsis  Peristalsis is the muscular movement of food along the gut  Sources of NSPs include wholemeal bread, brown rice & wholemeal pasta  Refined foods contain few if any NSPs 11

1. Sugar 2. Starch 3. Non-Starch Polysaccharides 12

1.Solubility  Sugars are white crystalline compounds that are soluble in water  Solubility is increased by heating the water  A syrup is formed when sugar is heated 2. Assists Aeration  Sugar denatures egg protein, enabling aeration to occur, e.g. in the making of sponge cakes – the egg when whisked with sugar becomes aerated 13

3. Crystallisation  This occurs if more sugar is added than can be absorbed by a liquid  Crystal particles are formed when the mixture cools  Crystallisation is used in the confectionery and sweet industry 14

4. Caramelisation  When sugars are heated, they produce a range of brown substances know as a caramel  There are ten gradual changes in sugar between melting and caramelisation  These stages occur between 104°C & 177°C  Eventually, the heat will cause carbonisation (burning) 15

5. Maillard Reaction  Sugar (Carbohydrate) + Amino Acid + Dry Heat = Browning of foods, e.g. roast potatoes 6. Sweetness  Sugar has varying degrees of sweetness based on a point scale using the tasting method  Sucrose has a relative sweetness of 100  Fructose has a relative sweetness of 170  Lactose has a relative sweetness of 15 16

7. Hydrolysis  Hydrolysis is the chemical breakdown of a molecule by adding water to produce smaller molecules  This occurs when water is added to a disaccharide to produce two monosaccharides  Hydrolysis is the reverse of the condensation reaction 17

8.Inversion  The hydrolysis of sucrose is also known as the inversion of sucrose (mixture of glucose & fructose), known as ‘invert sugar’  Inversion may be brought about by either: (a) heating sucrose with an acid; or (b) adding the enzyme invertase, or sucrase  Invert sugar is used in production of jam 18

1. Flavour  Starch (a white powder) is not sweet in flavour 2.Solubility  Starch is insoluble in cold water 3. Hygroscopic  This property relates to how starch absorbs moisture from the air e.g. biscuits soften if they are not kept air tight 19

4. Dextrinisation  Dextrins are shorter chains of starch  On heating, dextrins form longer chains & become brown-coloured substances called pyrodextrins  An example of dextrinisation is toasting bread 20

5. Gelatinisation is based on the principal that when starch is heated in the presence of water, starch grains swell, burst & absorb the liquid, resulting in the thickening of the liquid  As the temperature rises, this mixture becomes even more viscous, forming a sol (A sol contains particles that do not fully dissolve but are evenly dispersed throughout the liquid)  On cooling, this becomes a gel  An example of this is using flour to thicken soups and sauces 21

6. Hydrolysis  Hydrolysis is a chemical breakdown of a molecule by adding water to produce smaller molecules  Disaccharides become monosaccharides partly due to hydrolysis 22

1. Cellulose  Can absorb large amounts of water  Cannot be digested, however adds bulk to the diet (gives a feeling of fullness)  Aids the removal of waste from the body  Is insoluble in water 23

2. Pectin  Pectin is a polysaccharide found in fruit and vegetables  It is involved in setting jams & jellies  The following shows the pectin change in the ripening of fruit: Under-Ripe to ripe to Over-Ripe Protopectin to Pectin to Pectic Acid (pectose)  For pectin extraction : 1. Use fruit rich in pectin, e.g. Blackcurrants & Apples 2. Heat needs to be applied to the fruit 3. Add an acid, e.g. Lemon juice changes protopectin to pectin 24

3. Gel Formation  When pectin is heated in the presence of acid and sugar, water becomes trapped  The long chains of polysaccharides cool to form a gel  An example of this is in making jam 25

Dry Heat Moist Heat  Carbohydrate foods browns due to the presence of dextrins, e.g.Toast  Sugar caramelises, e.g. Caramel slices  Maillard reaction occurs because of the interaction between sugar & amino acids, e.g. roast potatoes  Cellulose softens, e.g. cooked vegetables  Starch grains swell, burst & absorb liquid, e.g. flour used to thicken sauces  Pectin is extracted by heating fruit in water with sugar & acid, e.g. jam making  Sugar dissolves in warm liquid, e.g. making syrups 26

 Sweetener - desserts  Preservative - jam  Caramelisation – caramel custard  Fermentation – yeast bread  Gel formation – sugar combines with pectin to form gel – jam making.  Colour – a sugar solution prevents discolouration of cut fruit. 27

 Thickener – sauces, soups, stews.  Hygroscopic – absorbs moisture to increase shelf life of cakes, keeps baking powder dry.  Dextrinisation – browning e.g.toast. 28

 Gel formation – jam pectin forms gel with acid and sugar.  Cellulose absorbs moisture and gives feeling of fullness.  Cellulose adds texture e.g. breakfast cereals 29

 Carbohydrates are used for heat and energy for the body.  They spare protein so it can be used for growth and repair.  Excess carbohydrate is changed to glycogen and stored in liver and muscle as an energy reserve or it is changed to body fat (adipose tissue) which insulates the body.  Cellulose moves food through intestine preventing constipation. 30

Mouth: Physically broken by teeth. Salivary Amylase breaks Starch into Maltose. Stomach: Physically churned up. Intestine: Pancreatic juice Amylase breaks (Pancreas) Starch into Maltose. Intestinal Juice: Maltase breaks (Ileum) Maltose into Glucose. Sucrase breaks Sucrose into Glucose & Fructose. Lactase breaks Lactose into Glucose and Galactose. 31

Absorption: Monosaccharides are absorbed through the villi of the small intestine into the blood stream and are carried to the liver in the portal vein. 32

 Monosaccharides can be oxidised to produce energy (cellular respiration).  Some monosaccharides are changed to glycogen and stored in liver and muscle as an energy reserve.  Excess carbohydrate is changed to body fat and stored in the adipose tissue under the skin.  Vitamin B1, B2 and Pyrodoxine are needed to metabolise carbohydrates. 33