F1+Food+groups

Food is any substance, whether processed, partially processed or raw, that is intended for human consumption. Includes beverages, gum and any substance used in the preparation or manufacture of food such as colorants Does not include cosmetics, tobacco or substanced used only as drugs. Nutrients are substances that are obtained from food. Nutrients can be divided into 6 main groups: proteins, carbohydrates, lipids, vitamins, minerals and water. A well-balanced diet consists of about 60% carbohydrate, 20-30% protein, and 10-20% fats. Foods containing these three components will also provide the essential vitamins and minerals, which include calcium, magnesium, sodium iron and sulfure, along with trace elements like iodine and chromium. A daily intake about 2 dm 3 of water is required. Malnutrition occur when either too little or too much of these essential components are taken **Carbohydrates** //Monosaccharides//: //Disaccharides and polysaccarides//:
 * Food and Nutrients**
 * Empirical formula CH 2 O
 * Contain a carbonyl group (C=O) and at least two -OH groups
 * Have between 3 and 6 carbon atoms
 * Pentose: C 5 H 10 O 5
 * Hexose: C 6 H 12 O 6 (glucose)
 * Monosaccharides can undergo condensation reactions to form disaccharides and polysaccharides.
 * Sucrose is a disaccharide formed from glucose and fructose
 * The link between two sugars is known as a glycosidic link

Examples of disaccharides: lactose and maltose Examples of polysaccharides: starch and cellulose

**Proteins**
 * They are large macromolecules made up of chains of 2-amino acids.
 * The amino acids bond to each other through condensation reations resulting in the formation of a polypeptide in wich the amino acid residues are joined to eachother by an amide link (peptide bond)
 * Each protein contains a fixed number of amino acid, connected to each other in strict sequence.
 * Example: gly-his-ala-ala-leu-… is known as the primary structure.
 * The secondary structure describes the way in which the chain of amino acids folds itself due to intramolecular hydrogen bonding
 * The tertiary structure described the overall folding of the chains by interactions between distant amino acids to give the protein its 3D shape
 * Quaternary structure: separate polypeptide chains can interact together to give a more complex strucutre. E.g hemoglobin has a quaternary structure, consisting of four protein chains grouped together around 4 heme groups

**Lipids (fats and oils)**
 *  Fats and oils are triesters formed from the condensation reaction of propane-1,2,3-triol (glycerol) with long chain carboxylic acids (fatty acids)
 *  Fats are solid triglycerides, examples butter, lard and tallow.
 *  Oils are liquid at room temperature, including castor oil, olive oil and linseed oil.
 *  Essential chemical difference:
 *  Fats contain saturated carboxylic acid groups (do not contain C=C bond)
 *  Oils contain at least 1 C=C bond and are unsaturated. Most oils contain several C=C and are called polyunsaturated