I have summarized the content of the polysaccharide part of the reader for the course Food Ingredient Functionality (FCH30306). Together with the summary of the knowledge clips (see my other uploads), it form a great preparation for the polysaccharide part of the exam. Good luck studying!
● Functionalities of polysaccharides:
○ Thickening → increase in viscosity.
○ Gel forming properties.
○ Stabilization
■ Emulsification, suspension, foam.
○ Film forming.
○ Aroma binding.
○ Glue properties.
○ Filling agent.
● Polysaccharide functionality depends on:
○ Chemical structure.
■ Sugar building blocks.
■ Charge.
■ Non-glycosidic substituents.
○ Branched vs. linear.
○ Molecular weight.
■ polydisperse vs monodisperse.
- Homopolysaccharides: polysaccharides made from one building block (sugar unit).
Cellulose, starch.
- Heteropolysaccharides: polysaccharides made from multiple building blocks (sugar
unit).
● Difference glycan/glucan → glycan is a generic name for all polysaccharides
(glycosidic linkage). Every polysaccharide is a glycan. A glucan is a polysaccharide
made from glucose.
● The polysaccharide structure dictates the shape of the polymer. The type of
monomer linkage plays an important role (a/b, 1-4, 1-2, 1-3).
○ Alpha: the OH group at C1 points downwards.
○ Beta: the OH group at C1 points upwards.
● The properties of polysaccharides are also determined by the presence of charged
groups and/or substituents.
○ Acids → COO-, SO4-- (always charged → not pH dependent), PO4--,
pyruvate.
○ Esters → methyl, acetyl or amide groups.
■ Neutralizing of charge.
■ Acetyl does not add charge to the molecule!
○ Number of charged groups or other substituents and their distribution is
important.
, ● (Pectin) high pH → more charge → more repulsion → higher viscosity.
● (Pectin) low pH → less charge → less repulsion → lower viscosity.
● In solutions, the hydrodynamic volume of the polysaccharides is important.
○ Larger hydrodynamic volume when DP is high.
○ Large hydrodynamic volume for linear polysaccharides than branched.
○ Larger hydrodynamic volume when the polysaccharide is charged.
● In High Performance Size Exclusion Chromatography, larger molecules (elute
more quickly) are less retained by the column than the small molecules.
○ Enzymes decrease the molecular weight.
● Polysaccharide production
from raw (agricultural)
products:
○ Directly from the crop.
■ Starch from
wheat.
■ Enzymes may
degrade the
pectin →
control!
○ From food industry
wastes.
■ Pectin from apple pomace.
● Polysaccharides may be highly variable.
○ Depending on the raw material and processing methods.
● However, a product sheet usually only contains generic information. This info might
thus not be true!
● During food processing, polysaccharide functionality may change.
○ Heating → starch gelatinization, degradation, retrogradation.
○ Polymer degradation → lower Mw → decrease in viscosity.
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