Carbohydrates

• Carbohydrates are made up of base units called simple sugars, which when combined form different carbohydrates.

  They are made during photosynthesis in plants. It is stored in the whole plant for future use. It is needed for growth and to form the structure in the plant.

  6CO2 + 6H2O ----(energy form the sun)----> C6H12O6 + 6O2
• Monosaccharides (simple sugars or base units)

  Glucose = fruit, vegetables, corn, honey, refined sugar, animal blood

  Fructose = fruit, vegetables, refined sugar, honey

  Galactose = not found in foods but milk of mammals
• Disaccharides (double sugars)

  They are made up of 2 monosaccharides joined together.

  Sucrose (Glucose + fructose) = sugar cane/beet

  Lactose (Glucose + galactose) = milk

  Maltose (Glucose + glucose) = barley, soya beans, sweet potatoes
• Polysaccharides (complex carbohydrates, they don't generally taste sweet)

  They are made up of many different sugars.

  Starch - formed during photosynthesis (many glucose units) - cereal crops

  Dextrin - bread, pastries

  Non Starch Polysaccharide/NSP/fibre (passes through the body without being absorbed) - fruit, vegetables, cereal crops, nuts

  Pectin - forms gels - fruits, vegetables
• Function in the body

  During digestion they are broken down to base units (glucose) before being absorbed into the bloodstream where energy is released. NSP passes through the body without being absorbed, but aids the digestive system.
• Carbohydrates are absorbed quicker than protein and fat sources.
• 1g carbohydrates = 16kJ/3.75kcal
• One-third of the diet should come from starchy food.
• Carbohydrate is a macro-nutrient that is needed by all animals. It is made by green plants during a process called photosynthesis. The main function of carbohydrate is to provide the body with energy. Dietary fibre is also known as non-starch polysaccharide. It is not absorbed by the body. Fibre helps the movement of food through the intestine.
• State the process by which plants make carbohydrates.

  Photosynthesis.
• Sugars are classified into 2 main groups - what are they?

  Monosaccharides and disaccharides
• Identify which carbohydrate the body uses for energy production during respiration.

  Glucose
• Name 2 different foods which you might eat if you needed some energy quickly to keep you going until lunchtime. Explain your choice.

  Chewy sweets and animal blood. They're sugars and are absorbed quickly. Short-term energy.
• Explain why someone taking part in a marathon might wat pasta before a race.

  It's because pasta contains polysaccharides, which are absorbed slowly, and good for long term energy.
• State which other nutrients are found in starchy foods.

  Fibre, calcium, iron, vitamins.
• Name 3 high fibre, starchy rich foods.

  Pasta, rice, nuts.
• Sugar

  During photosynthesis plants make carbohydrate and store it for future use. Sugar is the general name given to a type of carbohydrate, which plants and mammals make. There are several different sugars, but all of them are made from carbon, hydrogen and oxygen.
• All sugars are soluble in water. The sweetness of the sugars varies. Sweetness in food has been highly prized for centuries in many parts of the world. Sucrose from cane and sugar beet plants is used in a wide variety of food products.
• Monosaccharides

  Fructose (fruit sugar)

  Glucose (glucose)

  Galactose (milk sugar)

  Found in : Fruits, honey, plant juices, ripe fruit, beetroot, onions
• Disaccharides

  Sucrose (caster, brown, granulated, icing) - sugar cane, sugar beet

  Lactose (milk sugar) - Mammals milk

  Maltose (malt sugar) - cereals
• Nutritional Value

  Sugar supplies the body with energy. It contains no other significant nutrients. Sugar that is not used by the body for energy is converted to fat and stored under the skin. Excess consumption of sugar can lead to people becoming overweight or obese.

  Sugar is converted into acid by bacteria in the mouth. The acid attacks the enamel on the teeth and causes irreversible tooth decay.
• Honey

  Honeys are supersaturated solutions of sugar (about 75% sugars (glucose, fructose and sucrose)), water (20%), and flavours (%). Bees collect nectar (a mixture of sucrose, glucose, fructose and water) from flowers and as it passes through the bee, enzymes convert the sugars to form honey, which is deposited into honeycombs. Honey is sols as either liquid, after being processed by flash heating to 60-71C, or solid (granulated), where the sugars have crystallized out of the solution.
• Functions of sugar

  1. Sweetens
  2. Adds colour (caramelisation)
  3. Adds texture (e.g. biscuits - creates a soft crumb)
  4. Preserves (e.g. Jam, syrups)
  5. Acts as a raising agent (trap air)
  6. Aids fermentation (for yeast to grow)
  7. Coagulation (raises the temperature)
  8. Foam traps air and stabilizes
  9. Prevents enzyme browning (sugar syrup)
• As well as providing energy, starchy foods also supply other important nutrients to the body such as protein, calcium, iron, B vitamins and dietary fibre.

  Sugar, however, provides no other nutrients. It is sometimes referred to as 'empty calories'.

  Sugar is eaten in excess in the UK. A diet high in sugar can lead to tooth decay, type 2 diabetes, obesity, heart disease and some cancers.
• Balance is the key. Starchy foods give the body slow release glucose energy into the blood. Conversely, sugars are released quickly and can cause highs and lows in the blood sugar level and less stable energy levels in the body.

  Sugar in the form of glucose is the key energy source. Sugar can also be classified as follows:

  Intrinsic - Occur naturally in food e.g. fruit and sweet vegetables

  Extrinsic - Added to food e.g. sucrose (sugar cane, beet) as well as syrup, honey and artificial sweeteners.
• How much should we consume?

  Children 4-6: 5 sugar cubes, 19g

  Children 7-10: 6 sugar cubes, 24g

  Adults and children 11-18: 7 sugar cubes, 30g
• What is the Glycaemic Index (GI)

  The GI is a ranking of carbohdrate foods based on the effect they have on blood glucose levels. Foods that are absorbed slowly have a low GI ranking.

  Foods that are absorbed quickly have a higher GI ranking.

  This information gives people with diabetes important information to monitor their blood sugar levels.

  Low GI (55 or less) Fruit, non-starchy vegetables, wholewheat bread and legumes.

  Medium GI (56-69) brown rice, basmati rice and oats

  High GI (70 or more) white bread, cornflakes, white rice, white pasta (refined starches)
• Fibre/non starch polysaccharide also known as roughage/cellulose

  Sugars are either mono or disaccharides.

  Fibre or NSP is a polysaccharide. It is made up of many simple glucose molecules joined together and is also known as a complex carbohydrate.

  An average adult needs 30g of NSP a day.
• NSP

  Non-starch polysaccharides
• Insoluble fibre

  • Not easily broken down by the digestive system
  • Passes through the body unchanged
• Fibre passing through the bowel

  • Absorbs water
  • Increases the bulk of waste
  • Makes poo (stools) softer and easier to manage
• Fibre passing through the bowel

  • Helps to keep the bowels healthy
  • Prevents digestive problems such as constipation, haemorrhoids (piles), diverticulitis and cancer of the colon
• Fibre

  • Helps us feel full for longer
  • Reduces snacking
  • Helps to maintain a healthy weight
  • Keeps blood sugar levels constant, helping those with diabetes
• Soluble fibre is broken down by bacteria in the large bowel and can then be digested. The fibre reduces cholesterol in the blood and may reduce the risk of heart disease. Oats are often recommended in a cholesterol lowering diet as they contain a soluble fibre called beta-glucan.
• Pectin is also another soluble fibre. It is found in cell walls of plants such as fruits. It is used as a setting agent in jams and jellies.

  Examples of soluble: oats, barley, rye, most beans and peas, fruits and root vegetables.
• Excess fibre can leave you feeling bloated, with stomach cramps. Too much fibre creates the formation of phytates which can prevent the absorption of iron and calcium.
• Name 2 types of polysaccharides.

  Fibre and starch.
• Explain how NSP helps the digestive system to work more efficiently and prevent constipation.

  Insoluble fibre absorbs water and increases the bulk of any waste, making your poo softer and easier to manage. This keeps bowels healthy and prevent digestive problems including constipation.
• How can eating a wholegrain breakfast cereal help prevent a student from snacking on sweet foods in the morning.

  Eating a wholegrain breakfast cereal can help prevent a student from snacking as it's insoluble fibre which helps us feel full for longer.
• List 3 food that are good sources of soluble and insoluble fibre.

  Soluble: Oats, fruits, barley

  Insoluble: Nuts, corn, oats