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