Food Chem 1- Lecture 2

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Morgan.liberatore
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Food Chem 1- Lecture 2
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2012-02-11 16:38:39
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Food Chem
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Food Chem
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  1. What are the four major componenets making up foods and living systems?
    Lipids, Carbs, Proteins, Water
  2. Where are lipids extracted form?
    Lipids are extracted form a variety of biological sources- mainly plant and animal sources
  3. How are lipids characterized?
    All lipids are characterized by their datty sensation and lubrication properties
  4. Describe the soluability of lipids
    Lipids are insoluble in water and soluble in non-polar organic solvents such as hexane, chloroform or ether
  5. How are lipids obtained?
    By extracting dry biologican materials with hydrophobic organic solvents
  6. What are the subclasses of the Bloor Lipid Classification System?
    • Simple Lipids
    • Compound Lipids
    • Derived Lipids
  7. What are the sub-categories of simple lipids?
    • Fats
    • Waxes
  8. What are the sub-categries of compound lipids?
    • Phospholipids
    • Glycolipids
    • Lipoproteins
  9. What are the sub-categories of derived lipids?
    • Free fatty acids
    • Fatty alcohols
    • Hydrocarbons and oxygenated hydrocarbons
  10. How much of the extractable lipid is of the simple lipid class?
    >90%
  11. How much of the extractable lipid is made up of phospholipids?
    3-5%
  12. What is the general decinition of simple lipids?
    Esters of fatty acids connected to an alcohol (OH)
  13. What are the two sub-categories of simple lipids?
    • Fats
    • Waxes
  14. What is the definition of a fat?
    Esters of fatty acids connected specifically to glycerol
  15. In fats, how are fatty acids connected to the glycerol?
    Via an ester linkage
  16. What is another term for fats?
    Triacylglycerols or triglycerols
  17. How are fats triglyceride mixtures?
    Any fat represents millions of unique triglyceride compounds
  18. What does the term 'fat' imply?
    That the material is predominantly compose of triglycerids and also that it has a soldi character at room temperature
  19. What is implied by the term 'oil'?
    Triglycerides which have a lower melting point and are liquid at room temperature
  20. What is the definition of a wax?
    Esters of fatty acids esterified to an alcohol, OTHER than glycerol
  21. What is a 'true wax'?
    A fatty acid esterified to a simple fatty alcohol
  22. What are most waxes formed from?
    Generally, most waxes are formed from longer chain aliphatic fatty acids and alcohols and tend to be solid
  23. What is a common food application for waxes?
    • Sealing foods to prevent moisture loss (cheese)
    • As a polishing agend (apples)
  24. What is jojoba oil?
    A liquid wax which is largely comprised of linear esters of mono-unsaturated long chain fatty acids esterified to fatty alcohols
  25. What are some uses of jojoba oil?
    Used extensively in cosmetics and is also used as a low-calorie food ingredient with properties similar to olestra
  26. Why is jojoba oil so low in calories?
    It cannot be attacked enzymatically or digested
  27. What is an example of a fatty acid esterified to a complex alcohol
    cholesterol
  28. What is the general definition of a compound lipid?
    Compound lipids consist of a simple lipid (generally of the triglyceride type) conjugated (joined) to a non-lipid molecule
  29. What are the sub-categories of compound lipids?
    • Phospholipids
    • Glycolipids
    • Lipoproteins
  30. What are the sub-categories of phospholipids?
    • Lecithins
    • Cephalins
    • Inositols
  31. What is the definition of glycolipids?
    Contain sugar and other moieties (often phosphorous)
  32. What is a lipoprotein?
    Proteins complexed with lipid
  33. What is a triglyceride with one of their fatty acids replaced with a phosphoric acid known as?
    Phospholipids
  34. In a phospholipid what is the phosphoric acid in turn commonly conjugated with?
    Some other non-lipid molecule, usually a nitrogen base
  35. What is the fundamental structural unit of a phospholipid?
    Phosphatidic Acid
  36. What are the sub-classes of phospholipids?
    • Lecithins
    • Cephalins
    • Phosphatidyl inositols
  37. What is the 'x' constituent attched to the phosphate group in the lecithin group?
    Choline
  38. What is the 'x' constituent attached to the phosphate group in the cephalin group?
    Ethanolamine
  39. What is an example of a sub-class with a non nitrogenous ngroup attached to phosphatidic acid?
    Inositol
  40. How do phospholipids differ as a group relative to fats/waxes?
    Phospholipids have both hydrophobic and hydrophilic moieties in their molecular structure
  41. Why do phospholipids have excellent emulsifiying properties?
    Because they contain both hydrophobic and hydrophilic moieties
  42. What is a glycolipid/sphingolipid?
    Combination of glycerol or a glycerol-like backbone, fatty cids, carbohydrate and/or a nitrogen group
  43. What is a somple glycolipid?
    Comtains most of the elemebts of triglycerides (glycerol and 2 fatty acids) but a sugar has replaced one of he fatty acids and there is no phosphorous
  44. How does the sugar moiety affect a glycolipid?
    The sugar procides some polarity to the molecule
  45. What is a sphingolipid?
    Similar to a phospholipid, glycerol-like backbonem butalso conains nitrogen and has no ester linkage in the side chains
  46. Why can sphingolipids be classified as either a phosphilipid or glycolipid?
    Because sphingolipids often ontain either phosphate or carbohydrate
  47. What types of lipids are commonly associated with cell membranes in both plants and animals?
    Glycolipids and Sphingolipids
  48. Why are cell membrane lipids important?
    They are structurally important in therms of membrane permeability and transport of materials in and out of the cell
  49. What is a lipoprotein?
    complex structured protein-lipid complexes, their actual detailed structure is still being researched
  50. What types of lipid materials are associated with the structure of the lipoprotein?
    Either simple or compound lipids an be associated with the lipoprotein
  51. What common type of food is rich in lipoproteins?
    egg yolk
  52. What are lipoproteins used for?
    Natural emulsifiers
  53. How are lipoproteins used in our body?
    Lipoproteins circlate in our blood stream to carry lipids to tissues for metabolism or storage
  54. What are derived lipids?
    • Constituents derived fro the simple or compound lipid categories, but whih cstill retarin their hydrophobic character
    • This includes: Fatty Acids, Fatty alcohols, hydrocarbons and oxygenated derivatives thereof
  55. What is a fatty acid?
    Short to long chain aliphatic hydrocarbons with a carboxxyl group at one end and which may contain double bonds
  56. What are short chain fatty acids important for?
    Flavor compounds
  57. How are short chain fatty acids released?
    Can be released from lipids by lipolysis and can contribute to flavor, either good or bad
  58. Describe the flavor capabilities of long chain free fatty acids
    Longer chain free fatty acids have no flavor per se, but in the presence of mineral salts can give off a soapy flavor
  59. How can you lower the smoke point of oils?
    Presence of free fatty acids in fats and oils can lower their smoe point when used for frying
  60. What are short chain alcohols often used for?
    They are often major cobtributors to aroma and flavor
  61. What does Hexanol have the odor of?
    Freshly mown grass
  62. How are terpenes built?
    Terpenes are built up from fundamental isoproene unit (5 carbons, 2 conjugated double bonds)
  63. How are essenial oils typically obtained?
    Essential oils are typically obtained by steam distillation from plant materials
  64. What are monoterpenes important for?
    Monoterpenes and their oxygenated derivatives are important natural aroma and flavor constituents found in essential oils
  65. Why are monoterpenes easily extractable?
    Low molecular weight and volatile
  66. Which terpenes contribute more to the taste component of flavor?
    Sesqui and higher terpenes are less volatile and contribute to the tast component of flavor
  67. What is an oleoresin?
    Oleoresins are sesquiterpenes which have higher boiling point fractions
  68. What is the common name for the oxygenated derivatives of carotenes?
    Xanthophylls

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