Chapter 7: Water: The Universal Solvent

Solid, liquid, and gaseous

1) Helps control body temperature
2) Transports nutrients and waste products
3) Provides the solution for metabolic reactions

1) Influences the texture, appearance, and taste of food
2) Important heat medium in cooking
3) Important solvent for cleaning and sanitation
4) Critical for food preservation
5) Determines the likelihood of food spoilage by its presence or absence

Polar covalent bond

Electrically neutral since electrons are shared equally by the atoms.

Unequal sharing of electrons, which creates a dipole moment.

Weak bond resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.

Intermolecular

Positive H end of one H2O molecule is drawn to the negative oxygen ends of other H2O molecules

H-bonds in H2O create a high surface tension

1) Clings to something else
2) Have a higher melting and boiling point
3) Freezes faster than it thaws
4) Forms a crystalline structure in a solid state (ice)

H-bonding helps to dissolve polar substances

Sugars, starches, and proteins (polar molecules)

H2O boils at a lower temperature, decreasing atmospheric pressure

H2O boils at a higher temperature, increasing atmospheric pressure

• Higher amounts of flour

• Higher water content

• Oven temperature needs to be considered

Since it is such a great solvent

• Physical and chemical characteristics

• Flavour and colour

• Boiling point and freezing point

• Hydrogen bonding

100oC, yes

As hot as boiling water if not under pressure

Hotter than boiling water

1) Leaves food more flavourful and nutritious than boiling

2) Leavens baked goods

• CO2 is the gas solute dissolved in H2O when making carbonated beverages

• Oxygen also dissolves in H2O and is partially responsible for the taste of H2O

Alcoholic beverages, vinegars, fruit juice concentrates

Chemical properties

Lower the freezing point and increase the boiling point of water

Flavour compounds dissolved in H2O

1) Free Water
2) Bound Water (Water Activity)
3) Hydrate

Water type: H2O bound to other compounds is not available to support food spoiling

H2O has greater space when frozen than liquid, due to repelling of like charges.
Ice = less dense than water, so they float

Steam builds, pressure builds, water needs more energy, higher temperature to boil, which will cause foods to cook faster

Heat causes impurities from pipes to dissolve into water

It will raise the boiling point, gives pasta desired firm texture

Steam is a poor conductor of heat (if not under pressure)

Boiling point increases under pressure -> steam has higher T

Popovers

Just below the boiling point

Free water

Bound water

Hydrate

Compounds that have water driven off, free of water

Takes into account the water available to support enzyme activity and microorganism growth
The higher the water activity (0-1), the more perishable the food will be

1) Maintain body temperature
2) Transport nutrients and waste products
3) Serve as a reactant in metabolism
4) Become part of body tissue

Rainwater that enters lakes and rivers may be filtered to become drinking water.

Anything that makes a substance like water impure or unsafe.

Salmonella, E-coli, antibiotics, estrogen, garbage

1) Biological contaminants
2) Chemical contaminants
3) Physical contaminants.

bacterias, protozoa, viruses, organic waste

metal ions, antibiotic compounds, endocrine disruptors, acid rain

garbage and litter