文档介绍：Introduction to Food Science
Water
The Universal Chemical
Exits in Three States
Gas – Steam
Liquid – Water
Solid – Ice
Heat Transfer is necessary for conversion Conversion from: Water Vapor to Liquid Liquid to Solid
Heat must be removed =
Exothermic
Liquid to Vapor Solid to Liquid
Heat must be supplied =
Endothermic
Chemical Nature of Water
Covalent bonds between O
H H
Chemical Nature of Water
Covalent bonds between
O O
H H H H
O O
H H H H
Each molecule may be connected to 4 other molecules
Natural Water is a solution.
Trapped in capillaries of food -Water holding capacity Water activity aw
Water
Water activity (aw)
– Fresh Meat, fruit,vegetables
– Processed cheese, baked goods
– Aged cheese, and jams
- Molasses, dried figs
- Dried Fruit and corn syrup
- Chocolate, honey, noodles
Dried milk, dried vegetable