Food and its constituents

• Food groups by function

  • Food for energy (Energetic Food)
  • Food for growth (Building food)
  • Food for protection (functional food)
• Energetic Food

  • Carbohydrates like potato, Pasta, bread
• Building food


  • Protein like milk, cheese, meat, fish, Chicken
• Functional food

  • Fruits, vegetables, vitamins
• Monosaccharide


  Consists of one simple sugar, also called fast sugar (examples: glucose, fructose, galactose)
• Disaccharide


  Consists of 2 simple sugars, also called double sugar (examples: Maltose, Sucrose, Lactose)
• Polysaccharides


  Consists of 3 or more simple sugars, also called Slow Sugar (examples: Starch, glycogen, Cellulose)
• Protein


  A long chain of amino acids
• Peptide/polypeptide


  A short chain of amino acids
• Amino acids


  Nutrients coming out from the complete digestion of protein
• Lipids/fats


  Food for energy, consisting of fatty acids and glycerol
• Identification test is the test done on a certain food to identify its constituents
• Identification test of water involves placing a piece of bread over a Bunsen burner and observing drops of water
• Identification test of Carbohydrates

  1. Iodine test

  2. Fehling test
• Iodine test


  To identify the presence of starch, using iodine solution (color: brown, orange)
• Iodine test procedure


  • Add a few drops of iodine solution on a piece of bread, observe dark blue color
• Fehling test


  To identify the presence of reducing sugar (glucose), using Fehling solution (color: blue)
• Fehling test procedure

  1. Add a few drops of Fehling solution to the tested food, then heat the tube over the flame

  2. Result: formation of bricked precipitate
• Biuret test


  To identify the presence of protein or peptide, using copper sulfate (blue) and sodium hydroxide (colorless)
• Biuret test procedure


  1. Add a few drops of copper sulfate and sodium hydroxide to the tested food, shake the tube

  2. Result: Violet color appears
• Coagulation test

  To distinguish between protein and peptide, by heating the tested substance. If the tested substance coagulates (liquid to solid), it contains protein. If the liquid state remains, it contains peptide.
• Lipid identification test


  1. Put or rub the food on a piece of paper

  2. Result: Observation of translucent spot(Translucent spot indicates the presence of lipid)
• Molecular simplification of cooked starch by Salivary amylase

  "Schematize a functional diagram showing the molecular simplification of cooked starch by salivary amylase"

  A) cooked starch

  B) salivary amylase

  C) Maltose

  D) cuts

  E) water

  F) gives

  
• What are the two kinds of substances?

  • Organic Substances: Contain carbon (e.g., carbohydrates, proteins, lipids, vitamins)
  • Inorganic Substances: Do not contain carbon (e.g., water, mineral salts)
• What are the three classes of carbohydrates?

  1. Monosaccharides: Single sugar molecules (e.g., glucose, fructose, galactose)
  2. Disaccharides: Two sugar molecules (e.g., maltose, lactose, sucrose)
  3. Polysaccharides:3 or more sugar molecules (e.g., starch, glycogen)
• What is an example of a monosaccharide?

  Glucose
• What is sucrose classified as?

  A non-reducing sugar
• What are the three classes of proteic nature?

  Amino acids, peptides, and proteins
• What are the nutrients resulting from the complete digestion of lipids?

  Fatty acids and glycerol
• What is the purpose of identification tests in food analysis?

  • To identify the constituents of food
  • Uses chemical products called reagents
• What does the Iodine Test identify?

  • Identifies starch
  • Positive test: Color changes to dark blue
  • Negative test: Color remains brown-orange
• What does a positive result in the Fehling Test indicate?

  The presence of reducing sugar
• What does the Biuret Test identify?

  • Identifies presence of protein and/or peptides
  • Positive test: Color becomes violet
  • Negative test: Color remains blue
• What is the purpose of the Coagulation Test?

  • Distinguishes between protein and peptide
  • Positive test: Substance coagulates (indicates protein)
  • Negative test: Substance remains liquid (indicates peptide)
• What does the Sudan III Test identify?

  • Identifies lipid
  • Positive test: Red color appears
  • Negative test: Sudan III powder remains on surface
• How can you identify the presence of water in a substance?

  • Pass the substance over a flame
  • Positive test: Drops of water appear
  • Negative test: No observation of water
• What is the procedure to identify mineral salts?

  • Soak tested substance in distilled water
  • Add silver nitrate
  • Positive test: Formation of white precipitate
  • Negative test: No formation of precipitate
• What is the title of the functional diagram showing the chemical digestion of protein?

  A functional diagram showing the chemical digestion of protein by pepsin and trypsin enzyme in the presence of water
• What is the role of pepsin in digestion?

  Pepsin is an enzyme that digests protein into peptides
• Where is pepsin found?

  In the gastric juice in the stomach