Foods and Constituents

Foods and Constituents

• Food is a mixture of organic and inorganic matter
• Organic matter mainly consists of carbon, hydrogen, and oxygen from plant or animal sources
• Inorganic matter includes water and mineral salts and acts as functional foods

Organic Matter

• Carbohydrates, proteins, lipids, and vitamins are organic

Carbohydrates

• Energetic foods found in cereals, bread, jams, and desserts
• Simple carbohydrates include monosaccharides and disaccharides
  • Monosaccharides are formed of one sugar molecule, such as glucose, fructose, or galactose
  • Disaccharides are formed of two monosaccharides linked together, like maltose, sucrose, or lactose
• Complex carbohydrates include polysaccharides
  • Polysaccharides are formed of many monosaccharides linked, such as starch, cellulose, and glycogen

Proteins

• Building foods found in eggs, chicken, meat, and fish
• Formed of amino acids: there are 20 forms
• Polypeptides: many amino acids linked together by peptide bonds in a chain

Lipids

• Energetic foods found in oil, fat, and olive
• Formed of 3 fatty acids and 1 glycerol linked together

Vitamins

• Are found in fruits and vegetables

Inorganic Matter

• Water constitutes 60-70% of the body mass
• Mineral salts are unequally distributed in food
  • Major minerals are needed in large quantities
  • Oligo-elements are minerals found and needed in small quantities

Notes on Enzymes

• Lactase enzyme breaks down lactose
• Anything that ends with "ase" is an enzyme
• Dairy products are rich in calcium
• Amino acids are the smallest form of protein
• Polypeptides are when amino acids are linked together
• Proteins are the largest form of protein
• Fatty acids and glycerol are the smallest form of lipids
• Anything organic has carbon

Identification Tests

• Water detection involves heating food in a test tube; condensation indicates water
• Testing for sodium chloride involves adding silver nitrate; white precipitate of silver chloride will form
• Testing for calcium involves adding ammonium oxalate
• Glucose detection involves using a glucose strip test
• Reducing sugars (except sucrose) plus Fehling solution when heated will turn brick red
• Starch plus iodine water will turn dark blue
• Proteins plus coagulation test when heating the substance will produce small white clots
• Protein with biuret test consisting of sodium hydroxide and copper sulphate will turn violet
• Fat or lipid detection involves rubbing food on paper; a translucent spot indicates lipids

Notes on Sugars

• Reducing sugars are monosaccharides and disaccharides, except sucrose which gives negative results with the Fehling test

Digestion

• Digestion is the transformation of food from complex to simple using enzymes
• The digestive system includes the digestive tube and digestive glands

Digestive Tube

• The digestive tube is where food passes
• It consists of the mouth, esophagus, stomach, small intestine, large intestine, and anus

Digestive Glands

• Secrete juices with enzymes to aid digestion
• These include the salivary gland, gastric gland, pancreas, and glands in the small intestine

Steps of Digestion

• Mechanical digestion involves breaking large pieces into smaller ones through tearing and chewing, peristaltic movement, and the contraction of stomach and intestinal walls
• Chemical digestion transforms food into nutrients through enzymes

Notes on Digestion

• Digestive juices are liquids produced by digestive glands, containing enzymes
• Enzymes are chemical substances that simplify complex molecules
• Hydrolysis is the breakdown of complex molecules into simpler ones with water
• There are different types of digestion including Invitro, which occurs outside the body
• As well as Vitro, which occurs inside the body
• A substrate is a substance being digested
• The medium in the stomach is acidic (pH > 7), in the mouth is neutral (pH = 7), and in the small intestines is basic (pH < 7)