AC2.1

• Nutrients are structured into protein, lipids, carbohydrates, vitamins, minerals, and water.
• The chemical structure of nutrients and how this influences the way they are digested and used by the body is a key aspect of understanding nutrition.
• Applying this knowledge to the chemical properties and characteristics of different foods is crucial in understanding the nutritional value of food.
• The nutrients in foods are affected by different food preparation and cooking processes.
• Amino acids are organic compounds that contain a carboxyl group and an amino group, and join together in long chains (known as polymers) to form protein molecules.
• Amino acids are known as the building blocks for protein molecules.
• Amino acids are joined to more amino acids through a peptide bond, forming a polypeptide chain.
• Peptide bonds are formed through a condensation reaction, where the amino group (NH2) from one amino acid reacts with the carboxyl group of another amino acid, losing one water molecule in the process.
• A polymer is a substance made up of many similar units bonded together, including polymers, polysaccharides, and proteins.
• Polypeptide chains are held together by bonds (such as hydrogen bonds) to prevent the protein molecules from coming apart, forming structures such as the primary, secondary, tertiary, and quaternary structures.
• The chemicals that make up carbohydrates are: Oxygen (O), Hydrogen (H), Carbon (C), and the general formula for carbohydrates is C 6 H 12 O 6.
• Photosynthesis is where green plants make carbohydrates using water from the soil and carbon dioxide from the air to provide the carbon, hydrogen and oxygen.
• Simple carbohydrates are known as sugars, which are Crystalline substances that dissolve in water at different temperatures and also vary in sweetness.
• There are two different groups of sugars: Monosaccharides and disaccharides, where Mono = one (molecule) and Saccharide = sugar, and Di = two = two sugar molecules.
• Fructose is a Monosaccharide that makes a Pentose ring with 5 carbon atoms, while Glucose and galactose make Hexose rings with 6 carbon atoms.
• Glucose is found in ripe fruits and some vegetables, and forms a Hexose ring.
• Steps for drawing a Glucose Molecule include drawing 6 carbon molecules and drawing arms except for the first one, drawing 5 hydrogen to carbon bonds (4 on one side and 1 on the other), filling remaining spaces with (OH) group, and completing the ends with hydrogen bonds and 1 oxygen double bond.
• Disaccharides are double sugars that form when two monosaccharides join together, and are formed during condensation reactions.
• Sucrose is formed from one molecule of glucose and one molecule of fructose, and is the main sugar used in cooking.
• Lactose is 'Milk sugar', formed from one molecule of glucose and one molecule of galactose.
• Maltose is 'malt sugar', formed from two molecules of glucose.
• Polysaccharides are large molecules made up of mostly glucose, formed by green plants and used as a store of energy in roots, tubers and seeds.
• Starch is a Polysaccharide made up of Amylose (20-25%) and Amylopectin (70-80%), and is found in potatoes, wheat, rice, and other grains.
• Dextrin is formed with starchy foods are baked or toasted (DEXTRINISATION), and gives colour and flavour.
• Cellulose is a Polysaccharide that humans cannot digest, arranged in straight lines and gives plants their structure to grow tall.
• Pectin forms a gel with water to help jams set.
• Glycogen is made by some animals including humans to store energy in the liver and muscles.
• Denaturation takes a natural protein structure and makes it 'unnatural'.
• The quaternary structure of protein unravels back to a primary polypeptide chain.
• Once the protein structure is fully denatured it cannot be reversed.
• If egg whites are beaten until they are stiff, they are fully denatured and have no elasticity; they lose their original properties and aren't able to return to their former state.
• This is why such dishes as meringues and soufflés are light and fluffy.
• The biological value relates to how many amino acids are present in a protein.
• If a food has all the indispensable/essential amino acids, it has a high biological value (HBV).
• By eating two LBV proteins in the same meal, you can make up for the lacking amino acids in each, therefore giving yourself a meal with a high biological value (HBV).
• Excess protein that the body can’t use is passed out through your urine.
• Lipids are insoluble in water but soluble in solvents.
• Sources of Monosaccharides: Honey, dried fruits, canned fruits
• Sources of Disaccharides: Table sugar, cakes, beetroot, carrots
• Sources of Polysaccharides: Grains, vegetables, fruits, nuts, cereal bran