lipids Flashcards
What are lipids? what is their structure? what is their function?
Lipids are a diverse group of hydrophobic organic compounds primarily composed of carbon (C), hydrogen (H), and oxygen (O)
-hydrophobic / amphipathic
-non-polymeric
-diverse
They play essential roles in energy storage, structural components of cell membranes, and signaling molecules.
How are lipids traditionally defined? how has this definition changed?
Substances insoluble in water but soluble in organic solvents with functions ranging from energy storage to cellular signaling
Many substances are now classified as lipids even though they may be more soluble in water than organic solvents
what are categories of lipids?
Fatty acyls
Glycerolipids
Glycerolphospholipids
Sphingolipids
Sterol lipids
What are fatty acids?
Fatty acids are carboxylic acids with hydrocarbon chains that vary in length, degree of saturation, and functional group attachment.
What configuration do naturally occurring unsaturated fatty acids typically have? what effect does this have on its structure?
Cis configuration, which is more fluid.
What configuration do processed foods typically have regarding unsaturated fatty acids?
Trans configuration, associated with health risks.
How does the IUPAC Δ (Delta) System number carbons in fatty acids?
Numbers carbons from the carboxyl end, with every db being numbered
Provide the name of this fatty acid using the IUPAC Δ (Delta) System.
22:6 Δ 4,7,10,13,16,19
How does the ω (n-) System number carbons in fatty acids?
Numbers from the methyl end, only indicating the first db and assuming a methyl between each consecutive db
Provide the name of this fatty acid using the ω (n-) System.
22:6 n-3
what are acylglycerols? provide examples
Fatty acid esterified to a glycerol
-MAG, DAG, TAG
What is the significance of the sn-numbering system in acylglycerols?
It helps distinguish positions of fatty acids attached to glycerol.
what is the impact og chirality on FA sensory properties?
there is little impact on sensory properites
What are neutral lipids?
Neutral lipids are non-polar, mainly triacylglycerols
What are examples of polar lipids?
- Phospholipids (e.g., lecithin - phosphatidylcholine)
- Glycolipids
- Sterols (cholesterol, plant sterols)
What is the structure of phospholipids?
Contain a glycerol backbone, two fatty acid chains, and a phosphate group.
what does HPLC stand for? How is it used?
High performance liquid chromatography
separates lipids based on their polarity with neutral lipids eluting first and polar lipids eluting later
what types of lipids do you expect to see eluted first using HPLC? what will be eluted later?
Non-polar lipids first: Sterol esters, TAGs, sterols
Polar lipids last: Phosphatidylinositol, Phosphatidylcholine, Phosphatidylethanolamine, cardiolipin
What is lecithin and its role? what is it comprised of?
Lecithin is a naturally occurring phospholipid that acts as an emulsifier
-found in egg yolk and soybeans
composed of phospholipids, including:
Phosphatidylcholine (PC) (major component)
Phosphatidylethanolamine (PE)
Phosphatidylinositol (PI)
Phosphatidic acid (PA) (minor amounts)
Identify other important lipids in food systems.
- Sterols
- Waxes
- Fat-soluble vitamins (A, D, E, K)
- Carotenoids
What is the major emulsifier in food?
Lecithin.
What should be considered when looking at lipid composition in foods? why?
absolute amount should be considered, not just relative percent
some foods have a low amount of total lipids, but relative amounts of each type of lipid may be quite high
What are glyceroglycolipids?
Lipids with a glycerol backbone and carbohydrate groups attached at the sn-3 position
What are glycolipids? what are the two major types?
Glycolipids are a broader category that includes both glyceroglycolipids (glycerol-based) and sphingoglycolipids (sphingosine-based)
