Carbohydrates

Question 1

Formation of Carbohydrates

Answer 1

Carbohydrates are formed in plants by a process known as photosynthesis

Question 2

Define: Photosynthesis

Answer 2

Photosynthesis is the process by which green plants use energy from the sun to change carbon dioxide and water into glucose and oxygen

Question 3

What is the Equation for Photosynthesis

Answer 3

6CO2 + 6H20 —> Solar Energy & Chlorophyll —> C6H1206 + 602

Carbon Dioxide + Water —>Solar Energy & Chlorophyll —> Glucose + Oxygen

Question 4

Elemental Composition of Carbohydrates

Answer 4

• Carbon (C)
• Hydrogen (H)
• Oxygen (O)

Question 5

Classification Of Carbohydrates

Answer 5

• Monosaccharides
• Disaccharides
• Polysaccharides

Question 6

Monosaccharides: Structure

Answer 6

A simple sugar that contains one single sugar unit. It is the smallest unit of a carbohydrate

Question 7

Monosaccharides: Chemical Formula

Answer 7

C6H12O6

Question 8

Monosaccharides: Examples and Sources

Answer 8

• Glucose: Fruit
• Fructose: Fruit & Honey
• Galactose: Digested milk

Question 9

Disaccharides: Structure

Answer 9

Formed when two monosaccharides join together resulting in the loss of a water molecule (condensation reaction)

Question 10

Disaccharides: Chemical Formula

Answer 10

C12H22011

Question 11

Disaccharides: Examples & Sources

Answer 11

• Maltose: Barley
• Sucrose: Table Sugar
• Lactose: Milk

Question 12

Polysaccharides: Structure

Answer 12

When 3 or more monosaccharides join together resulting in the loss of a water molecule with each new link (condensation reaction).
Chains can be straight or branched

Question 13

Polysaccharides: Chemical Formula

Answer 13

(C6H10O5)n
* n refers to the number of monosaccharides joined together

Question 14

Polysaccharides: Example & Sources

Answer 14

• Cellulose: fruit and vegetable skins
• Glycogen: meat
• Starch: potatoes

Question 15

Properties of Sugar: Solubility

Answer 15

• A white crystalline compound
• Soluble in water
• Syrup forms when a large amount of sugar is dissolved in a small amount of water
  E.g. preservative in canned fruit, e.g. canned peaches

Question 16

Properties of Sugar: Sweetness

Answer 16

• All sugars are sweet and give an appetising flavour to food, however some are sweeter than others
• Sugar is used to add flavour and sweetness to food
  E.g. shortbread, cupcakes

Question 17

Properties of Sugar: Aeration

Answer 17

• When sugar is whisked with egg aeration occurs
• Sugar denatures egg protein, entrapping air bubbles.
• Whisking creates heat that sets egg albumin, creating a temporary foam
  E.g. Meringues

Question 18

Properties of Sugar: Maillard reaction

Answer 18

• Non enzymic browning of food due to a reaction between certain amino acids and sugars under dry heat.
  E.g. Roast meat

Question 19

Properties of Sugar: Caramelisation

Answer 19

• On heating, sugar melts and caramelises.
• Caramelisation occurs at 160C
  E.g. caramel squares

Question 20

Properties of Sugar: Crystallisation

Answer 20

• When a liquid has dissolved as much sugar as it can, it is saturated. If more sugar is added, crystals of sugar form in the solution and solidify when cooled
  E.g. fudge

Question 21

Properties of Sugar: Hydrolysis

Answer 21

• Occurs during digestion.
• Water and enzymes split disaccharides into two monosaccharides
  E.g. lactose into glucose and galactose

Question 22

Properties of Sugar: Inversion

Answer 22

• When a liquid sucrose solution is heated with an acid/enzyme
• Causing the disaccharide to split into monosaccharides.
• An invert sugar
  E.g. Jam making

Question 23

Properties of Starch: Solubility

Answer 23

• Starch is a white, non-crystalline powder. It is insoluble in cold water

Question 24

Properties of Starch: Flavour

Answer 24

• Starch is not sweet in flavour

Question 25

Properties of Starch: Hygroscopy

Answer 25

- Has the ability to absorb moisture from the air - Cause uncovered foods to soften and lose crunch E.g. keeps cakes moist

Question 26

Properties of Starch: Gelatinisation

Answer 26

-When starch is combined with liquid and heated to 55-70C, grains swell, burst and absorb liquid around them - Increased viscosity - As temperature increases above 85C it forms a sol - When cooled a gel formed E.g. roux sauce, pastry

Question 27

Properties of Starch: Hydrolysis

Answer 27

- Occurs during digestion. - Water and enzymes split polysaccharides into two disaccharides E.g. maltose

Question 28

Properties of Starch: Dextrinization

Answer 28

- dextrin's form on starch food under dry heat - On further heating they combine to form pyrodextrins - Cause a colour change on the food surface E.g. toast

Question 29

Properties of Non-Starch Polysaccharides: Cellulose

Answer 29

- Insoluble in water - Cannot digested by the body - Absorbs water as it passes through the intestinal tract. stimulating peristalsis - Prevents bowl disorders, e.g. constipation

Question 30

Properties of Non-Starch Polysaccharides: Gums

Answer 30

- Soluble in water - Absorbs large amounts of water to form a thick gel with a firm texture E.g. Ice-cream

Question 31

Properties of Non-Starch Polysaccharides: Pectin

Answer 31

- Present in cell walls of of fruit and vegetables - Used as a setting agent - Can absorb water to form a gel with heat and and acid, e.g. lemon juice E.g. jam-making

Question 32

Effects of Heat on Carbs: Dry Heat

Answer 32

- Dextrinization: toasting bread - Caramelisation: crème caramel - Maillard Reaction: roast beef

Question 33

Effects of Heat on Carbs: Moist Heat

Answer 33

- Syrup formation: tinned peaches - Gelatinisation: white sauce - Cellulose softens: potatoes - Pectin extraction: jam

Question 34

Biological functions of carbohydrates: Heat & Energy

Answer 34

- Supply the body with heat and energy. Helps keep the body at 37C and provides energy for all activities

Question 35

Biological functions of carbohydrates: Protein-sparing functions

Answer 35

- Protein-sparing function. By eating enough carbohydrates proteins can do their primary function of growth and repair of cells

Question 36

Biological functions of carbohydrates: Dietary fibre

Answer 36

Cellulose absorbs water as it passes through the intestinal tract. stimulating peristalsis. This prevents bowl disorders, e.g. constipation

Question 37

Biological functions of carbohydrates: Dietary fibre

Answer 37

Excess carbohydrate intake is converted to glycogen and stored in the liver and muscles as an energy reserve - This may be converted to fat and stored in the adipose tissue under the skin, which insulates the body and act as another energy reserve

Question 38

Dietary Disorders due to Excess Carbohydrate Consumption

Answer 38

Too much starch & sugar: type 2 diabetes and cavities Too little cellulose: bowel disorders

Question 39

Digestion of Carbohydrates: Mouth

Answer 39

Organ: Mouth Secretion: Saliva Enzymes: Salivary amylase Substrate: Starch Product: Maltose

Question 40

Digestion of Carbohydrates: Pancreas

Answer 40

Organ: Pancreas Secretion: Pancreatic Juice Enzymes: Amylase Substrate: Starch Product: Maltose

Question 41

Digestion of Carbohydrates: Small Intestine

Answer 41

Organ: Ileum Secretion: Intestinal juice Enzymes: Maltase, Sucrase, Lactase Substrate: Maltose, Sucrose, Lactose Produce: Glucose and Fructose

Question 42

Carbohydrate Absorption

Answer 42

- After digestion the monosaccharides glucose, fructose and galactose are ready to be absorbed by the small intestine into the bloodstream where the hepatic portal vein transports them to the liver

Question 43

Carbohydrate Utilisation

Answer 43

- In the liver fructose and galactose are converted to glucose, then: - oxidised to produce heat and energy - converted to glycogen and stored in the liver and muscles as an energy reserve.