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Carbohydrates
 

Carbohydrates

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Year 13 Edexcel Food Tech

Year 13 Edexcel Food Tech

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    Carbohydrates Carbohydrates Presentation Transcript

    • Digestion Quiz
      • Why is Saliva needed at the starting part of digestion?
      • When chewing up your food you unconscientiously form it in a
      • ball shape which is known as a...?
      • This is then passed down your…?
      • By which motion?
      • In the stomach the ball is mixed with what to kill any bacteria?
      • Which enzyme is present in the stomach to help break down
      • food into peptides and amino acids?
    • Digestion Quiz
      • This balled gets churned up into…?
      • What is the ring of muscles called that opens to let the ball
      • pass into the small intestine?
      • There are 3 sections of the small intestine these are?
      • What is the role of bile in digestion?
    • Answers to digestion quiz
      • To provide the enzyme amylase and moisten the food.
      • Bolus
      • Oesophagus
      • Peristalsis
      • Hydrochloric acid
      • Pepsin
      • Chyme
      • Pyloric sphincter
      • duodenum, jejunum and the ileum
      • Bile salts which emulsify fat. Fat is normally insoluble in water. The bile salts are released into the duodenum making it easier to break down fat. The bile allows the fats to mix in with the watery digestive juices, and allows the enzyme lipase to digest the fats efficiently.
    • Carbohydrates
      • Aims of today’s lesson:
      • To develop knowledge of carbohydrates, sources, functions and structure
    • Carbohydrates
      • Carbohydrates are an important MACRO nutrient because they:
      • Carbohydrates are our primary source of energy. 
      • Supply energy for all activities
      • Supply energy to maintain normal body temperature
      • Supply indigestible fibrous materials to aid digestion
      • Are important in the structure of cells
    • Carbohydrates
      • Carbohydrates are made up of:
      • Carbon + hydrogen + oxygen
      • When digested the sugars they contain are
      • Broken into glucose
      • Glucose circulates bloodstream giving energy
      • Any glucose left turns to glycogen stored in
      • liver
    • How are they broken down?
      • The liver digests carbohydrates by breaking them down into simple sugars (glucose), which stimulates the production of insulin in the pancreas. The insulin functions to get the sugar into the body’s cells to be used as energy.
    • How are they broken down?
      • The two different types of carbohydrates affect the production of insulin differently.
      • Simple carbohydrates, insulin levels spike faster, and the carbs are used up more quickly for energy.
      • Complex carbohydrates take longer to digest, resulting in longer lasting energy, and less of an insulin reaction in the body.
    • What if we eat too many carbs?
      • If the body produces too much glucose, it will be stored in the liver and muscle cells as glycogen, to be used for when the body needs an extra burst of energy. Any leftover glycogen that isn't stored in liver and muscle cells is stored as fat.
    • Carbohydrates – classification of commonly occurring carbohydrates Pectin Gums Maltose Sucrose Lactose Complex polysaccharides Disaccharides Starch Cellulose Simple polysaccharides Non-sugars (not sweet) Glucose Fructose Monosaccharides Sugars (sweet)
    • Monosaccharides
      • Glucose - Foods with a high concentration of glucose (such as sports drinks) need no conversion, so they raise blood sugar rapidly.
      • Fructose - Fructose (the sugar in fruit), however, converts slowly.
    • Dissaccharides
      • Maltose – produced during the malting of cereals such as barley.
      • Sucrose - This is the white powdery or granular substance we typically refer to as "sugar" when we are cooking or baking.
      • Lactose - the sugar found in the milk of mammals. People who are "lactose intolerant" can't digest this sugar properly.
    • Simple Polysaccharides
      • Starch - the energy storage form of carbohydrates found in plants, especially in the seeds and roots. E.g’s rice, wheat, corn, carrots and potatoes. Starches are not water-soluble and require digestive enzymes called amylases to break them apart.
      • Cellulose (fibre) - the structural component of plants. Cellulose helps plants keep their shape. Unable to digest cellulose.
    • Cellulose - Fibre
      • Indigestible complex carbohydrate that comes from plant cell walls. 
      • Fibre is a unique type of carbohydrate because it contains zero calories, zero vitamins and cannot be digested.  Therefore, it does not provide your body with any energy or nutrients. 
      • Insoluble Fibre vs Soluble Fibre
      • There are two types of fibre; insoluble and soluble.  Insoluble fibre absorbs water in your intestine to form a bulky mass which then helps clear waste materials from your digestive tract.  Soluble fibre dissolves in the water in your intestine to form a thick gel which then holds food in your digestive tract for longer.
    • Complex Polysaccharides
      • Pectin - Essential in jam making. Occurs naturally in plant cells and cell walls. Pectins in the correct conditions form gels and preserves. Pg 17-18
      • Gums - Ability to absorb large amounts of water and form firm gels used to thicken, stabilise and emulsify. Plants produce gums on their stems. They are dried and sold commercially. E.g. gum arabic, gum karaya, gum ghatti.
    • Gelatinisation of starch
      • Starch can form a gel which can thicken food, gravy, soup, lemon pie filling, etc.
      • Starch + cold water = suspension
      • When heated = viscosity increases
      • YouTube - Carbohydrates & You, Part 1, Advanced Nutrition Lecture
    • Exam Questions
      • Name two monosaccharides found in foods (2)
      • Name three disaccharides found in foods (3)
      • Name two simple carbohydrates (2)
      • Name two complex carbohydrates (2)
    • Exam style answers
      • Glucose and fructose
      • Maltose, Sucrose and Lactose
      • Starch and Cellulose
      • Pectin and Gums