PCOG LAB (MIDTERM)

• Are aldehyde or ketone derivatives of polyhydric alcohols or compounds that yield these derivatives upon hydrolysis

  Carbohydrates
• are organic molecules containing carbon, hydrogen, and oxygen

  Carbohydrates
• Examples of Carbohydrates

  1. Sugars - sucrose (table sugar)
  2. Oligosaccharides (maltodextrin)
  3. Polysaccharides (cellulose)
• Difference Between Aldehydes & Ketones

  A) Aldehydes

  B) Ketones

  C) R-CHO

  D) R-CO-R'

  E) End of the chian

  F) Middle of the chain

  
• Scientific Name of Kamote

  Ipomoea batatas
• Introduced by Spaniards from Mexico

  Kamote
• One of the commonest edible food in the Philippines

  Kamote
• "Energy giving" food

  Kamote
• Roots are low in protein, calcium, and iron


  Kamote
• Common Sources of Carbohydrates

  • Cornstarch
  • Rice flour
  • Wheat flour
  • Rye & Millet flour
  • Chinese chestnuts
  • Chia seeds
  • Raisins(seedless)
  • Goji berries (dried)
  • Zante currants (dried)
  • Mejdool dates
  • Cassava
  • Sweet potato (cooked)
  • Potatoes (cooked)
  • Peas (sprouted)
  • Litchis (dried)
  • Figs (dried)
  • Tamarinds
  • Apricots (dried)
• What are the tests for Carbohydrates?

  1. Iodine Test
  2. Molisch's Test
  3. Moore's Test
• Other tests for Carbohydrates

  A) brick-red ppt at the bottom

  B) bluish color upon heating

  C) cherry red color upon cooling

  D) change of color to red = presence of galactose

  E) osazone cystals

  F) Cu sulfate, Na carbonate, Na citrate

  G) Orcinol, HCl, FeCl3 solution

  H) Resorcinol, HCl

  I) Phloroglucinol, HCl

  J) Phenyl hydrazine, Na acetate, Glacial acetic acid

  K) reducing sugar

  L) pentoses

  M) monosaccharides with ketonic

  N) galactose and lactose

  O) confirmatory test

  P) Benedict's Test

  Q) Bial's Test

  R) Seliwanoff's Test

  S) Phloroglucinol test

  T) Osazone test

  
• Use: This test is used to differentiate polysaccharides from the rest of carbohydrates.

  Iodine Test
• Principle: based on the absorptive properties possessed by large polysaccharide molecules.

  Iodine test
• Reagent of Iodine Test

  0.5 mL iodine diluted in 5 mL distilled water
• Positive Result of Iodine Test

  Blue or red-colored iodine complexes

  • If blue color appears, amylase or starch is present in the solution
  • If reddish-purple color appears, dextrin is present
  • If reddish-brown color appears, glycogen is present
• Use: It is a screening test for confirming the presence or absence of carbohydrates in a given solution.

  Molisch's Test
• Principle: This test is based on the reaction of alpha-naphthol with carbohydrates in the presence of sulfuric acid

  Molisch's Test
• Reagent in Molisch's Test

  Molisch’s reagent: 5% alpha-naphthol solution in ethyl alcoho
• Positive result of Molisch's Test

  Violet-colored ring is formed at the junction of the two liquids i.e. solution with Molisch’s reagent and the sulfuric acid

  • Remider: Too much H2SO4 can cause charring carbohydrates - a black ring will be formed, giving a false negative test
• Use: It is a special test for sugars with free aldehyde or ketone groups


  Moore's Test
• Principle: The color reaction is the result of polymerization of the aldehydes which becomes free


  Moore's Test
• Reagent of Moore's Test

  Sodium Hydroxide
• Positive result of Moore's Test


  This test is based on the liberation of aldehydes which subsequently polymerize to form a resinous substance, caramel

  • Reminder: glucose and starch give positive results to the Moore’s test because they are reducing sugars. In the other hand, the sucrose being a non-reducing sugar does not have a free aldehyde or ketone group. Therefore, there is no liberation of aldehyde and no polymerization reaction.
• Specific test for differentiating monosaccharides from disaccharides?

  Barfoed's Test
• Use: It is a differentiating test to distinguish between monosaccharides and disaccharides


  Barfoed's Test
• Principle: Reducing sugar undergo tautomerization in a mildly acidic medium to form enediols.

  Barfoed's Test
• Reagent of Barfoed's Test

  Copper acetate in glacial acetic acid
• Positive result of Barfoed's Test

  The formation of red precipitates after the initial first 5 minutes indicates the presence of a monosaccharide. If precipitates are formed after 15 minutes, a disaccharide is present in the test solution
• Physiologic Function of Carbohydrates

  In plants, carbohydrates produced by photosynthesis are well known for their essential role as vital sources of energy and carbon skeletons for organic compounds and storage components
• Variety of Starches

  • Potato Starch
  • Rice Starch
  • Wheat Starch
  • Corn Starch
• Potato Starch


  • Generally, found in the form of simple granules, which are sub-spherical, somewhat flattened irregularly ovoid in shape
  • Sizes vary from 30–100 μ
  • Hilum is present near the narrower end with well-marked concentric striations
• Rice Starch

  • Granules are simple or compound
  • Simple granules are polyhedral, 2-12 μ in diameter
  • Compound granules are ovoid and 12-30 μ x 7-12 μ in size
  • Compound granules may contain 2-150 components
• Wheat Starch


  • Simple lenticular granules which are circular or oval in shape and 5-50 μ in diameter
  • Granules contain hilum at the center and concentric faintly marked striations
  • Rarely, compound granules with two to four components are also observed
• Corn Starch


  • Granules are polyhedral or rounded, 5-31 in diameter
  • Granules have distinct cavity in the center or two to five rays cleft
• The reaction of the cell sap of most plants is acidic and some tissues such as unripe fruits and leaves are acidic even to the taste
• This acidity is due to organic acids
• Organic acids are of fundamental importance in all plant species
• Involved in many and diverse metabolic pathways:

  • energy production
  • carbon storage
  • stomatal conductance
  • biosynthesis of amino acids
  • plant–microbe interactions
  • mechanism allowing plants to deal with excess cations
  • changing osmotic conditions
• are involved in the regulation of a broad range of basic cellular processes, e.g. the modification of cellular pH or the redox state

  Organic acids