Functional polysaccharides Flashcards
What are the 3 solvent and solute interactions?
Solvent-solute
Solute-solute
Solvent-solvent
What does viscous ideal mean?
Material changes shape
What does elastic ideal mean?
Material retains shape
What is viscoelastic?
Mix between viscous and elastic
Examples of viscoelastic materials
Ketchup (fluid) and jelly (solid)
What do thickening agents increase?
Solution viscosity
Resistance to external force
Internal friction
Solvent-solute interactions
How do thickening agents work?
Formation of polymers which capture water molecules
What are gelling agents?
Macromolecules that cause liquids to have solid-like consistency (jelly)
How do gelling agents work?
Formation of cross-linked polymers to increase solute-solute interactions
What are anomeric effects?
Differences between alpha and beta polysaccharides (alpha right carbon is on the bottom whereas beta is on top)
What effects polysaccharides secondary structure?
Anomeric effects
Bond positions
Number of units
What effects polysaccharide tertiary structure?
Hydrogen bonding
Other molecules
Geometry
Differences between amylose and cellulose
Amylose= alpha-D-Glucose
Cellulose= beta-D-Glucose
Amylose has helix structure, cellulose has chained structure
What occurs when flour is added to water then heated?
Dry grain becomes dispersed and swollen
Swollen grain becomes a dissolution
Dissolution becomes thickening or gelling structure
Chains in gels are formed by what?
Electrostatic interactions
Hydrogen bonding
Hydrophobic bonding
Entropic interactions
Are gel chains stronger or weaker than solution chains?
Stronger
What is gelling point dependent on?
Temperature
Ions
pH
Co-solutes
What are the 2 areas of cellulose?
Amorphous and crystalline
How do modifications in the amorphous area effect cellulose?
Changes structure and functionality
What is the structure of galactomannans (thickener)?
(1-4)-beta-D-Mannose backbone with (1-6)-alpha-D-Galactose side group
What is the structure of alginates (gelling)?
(1-4)-beta-D-mannuronic and alpha-L-guluronic acid
Structure of pectin
(1-4)-alpha-D-galacturonate backbone with galacturonic acid and methyl-esterified side chains
What does high esterification (>50%) cause in pectin?
High methoxy (HM) pectin which causes gelation through hydrophobic bonding
What does low esterification (<50%) cause in pectin?
Low methoxy (LM) pectin which forms gels with calcium ions through cross linking
What is degree of blockiness?
Measure of distribution of ester groups in pectin chains
What does degree of blockiness effect?
Cross-linking
What is xanthan gum?
Exocellular polysaccharide of bacterial fermentation
Structure of xanthan gum
(1-4)-beta-D-glucose backbone with side chains of 2 mannose units
What does xanthan gum form?
Weak gels
