Water simply doesn’t behave like other liquids
Functions
Water Content of Some Foods
Structure
Water is Polar!!!!
Water has relatively large dipole moment
Hydrogen Bonds Exist Between Water Molecules
Unique Properties of Water
Tetrahedral structure

LIQUID STATE

Solid State

GASEOUS STATE
KINDS OF WATER (DEGREE OF WATER BINDNESS)

Water activity (aw)
Relationship Water Content & Water Activity
Water Activity of Common Food Products
In summary
Factors that Influence Water Activity
Moisture Sorption Isotherms (MSI)
Moisture Sorption Isotherm
Zones in Isotherms

WATER ZONES ANALOGY

Moisture Sorption Isotherm
Adsorption & Resorption
Sorption and Desorption
Water Sorption Hysteresis
Chemical/Biochemical Stability
Some important points in Aw/Stability Diagram
aw affects the textural properties of foods
Water activity affects the storage stability of deydrated products (powders)
Moisture migration of multicomponent products
Shelf-life/Packaging

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