Chapter 7 water food science

Name four functions of water in the body.

(List four:) transport nutrients, remove waste products, help maintain body temperature, act as a reactant for chemical reactions, become part of body tissue

List three tips for converting standard recipes for use at high altitudes.

(List three. Answers will vary. See page 184 in the text.)

The force of the weight determined by the pull of the earths gravity pressing down on a surface is ________

Atmospheric pressure

Anhydrous

Free of water

Lemon juice is an example of ________

Free water

List the three types of water solutions and give an example of each. Name the solute in each example.

Gas-in-water, liquid-in-water, and solid-in-water (examples may vary)

The chemical formula for water is _______

H2O

The term hard water refers to water that __________

Has metal ions in it

Why does water freeze faster than it thaws?

Hydrogen bonds can easily form and hold water molecules into a rigid structure. It is more difficult for hydrogen bonds to be broken so water molecules can slide by one another freely.

In a hydrogen bond, the ________

Hydrogen of one is attracted to the oxygen of another

What is not a property of water?

It is a non polar molecule

An advantage of cooking in steam is ______

It is faster than boiling when pressure is added, foods are more flavorful, and foods are more nutritious

In which state is water most dense?

Liquid

Describe one method of cooking each of the following foods with water: pasta, eggs, and vegetables.

Pasta-Adding 5 mL (1 teaspoon) salt per 1 L (1 quart) of cooking water to raise the boiling point 0.5°C to 1.0°C (1°F to 2°F). This higher temperature helps give pasta a desirable firm texture. Eggs-Place an egg in a custard cup. Place the custard cup in a saucepan with gently boiling water in the bottom. Steam the egg for 4 minutes. Vegetables-Place vegetables in a steamer basket with a small amount of water, bring to a boil, cover, and let steam surround the vegetables.

Atmospheric pressure can change the amount of energy needed to break hydrogen bonds in water. In which of the following places will water boil at the lowest temperature?

Pike's peak

What is an example of a physical contaminant in water?

Plastics

________ bonds are formed within a water molecule

Polar covalent

Water performed all the functions in the body except _________

Providing energy

Free water is water that_______

Readily separates out of food

It is best to consume water ________

Regularly throughout the day

The water that will give the most successful food preparation is ________

Soft water

True/ false Atmospheric pressure is based on the pressure of the atmosphere on an object at sea level

True

True/ false Ice floats because water is more dense in the liquid state

True

True/ false Most bottling companies have established water standards for their products to maintain a uniform product flavor

True

True/ false Steam that is not under pressure is the same temperature as boiling water

True

True/ false The shape of water molecules contributes to the physical characteristics of water

True

True/ false Water is a nutrient

True

polar covalent bond

Unequal sharing of electrons

Hydrogen bond

Wake attraction between positive and negative ends of two molecules

Give the two reasons you should drink water rather than just obtain water as parts of other foods

Water has no calories as compared to soft drinks that provide a lot of sugar and excess phosphorus. Many foods that are high in water are also high in either sugar or salt

Bound water

Water that is tied to the surface of large males unless like protein and starches

The boiling point of water at sea level is ___—-

100•c

A meniscus is caused by water's ________

Adhesive property

Explain how hot water (steam) acts as a leavening agent in baked goods.

As batters and doughs are heated, water expands and moves to the gaseous phase requiring more space. Small pockets of steam create cells similar to those formed by carbon dioxide from chemical leavening agents. Heat solidifies the batter or dough around the air and steam pockets. Steam trapped in the dough is absorbed during cooling.

Impurities in water ______

Can change the physics and chemical characteristics

True/ false Solid foods such as bread do not contain water

False

True/ false The higher the altitude, the less water you will need to drink to stay hydrated

False

True/ false The increased surface tension of water accounts for its lower melting and boiling points as compared to other liquids

False

True/ false The three types of contaminants found in water are biological, chemical, and microbial

False

True/ false Water softeners are used to remove ions that create temporary water hardness

False

True/ false When ice is formed, the water molecules form a spherical shape

False

Explain why the boiling point of water changes as altitude changes

When there is less atmospheric pressure on the water, the molecules need less energy to escape. When there is more atmospheric pressure on the water the molecules need more energy to escape. At high altitudes, the atmospheric pressure is lower and water will boil at lower temperatures. At low altitude, atmospheric pressure is higher and water will boil at higher temperatures.

No polar covalent bond

electrons are shared equally

Water makes a good medium for cooking food because __________

heat is transferred throughout by conduction and convection

Tea and coffee are not brewed in boiling water because boiling water _______

releases bitter polyphenols

when salt and sugar are added to water, ________

the boiling point is higher and the freezing point is lower

water activity is ___________

the water available to support enzyme activity

cooled boiled water has a flat taste because ______

there is a lower dissolved oxygen level