FOOD CHEM water charact

61問 • 1年前

velante

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問題一覧

Water that cannot be easily extracted as it is bound to polar and ionic groups in food.

Bound Water

A mixture where larger molecules than those in a solution are dispersed in a surrounding medium.

Colloidal Dispersion

Strong bonds that hold two hydrogen atoms and one oxygen atom together in a water molecule.

Covalent Bonds

Water that can be easily extracted from food by squeezing, cutting, or pressing.

Free Water

A food-processing method that converts ice directly to vapor without passing through the liquid phase (sublimation).

Freeze-Drying

An elastic solid consisting of a solid continuous phase and a liquid dispersed phase

Gel

Contains 11–20 grains per gallon and is high in calcium and magnesium bicarbonates or sulfates, leading to reduced cleaning efficiency.

Hard Water

Weak bonds between polar compounds where the hydrogen atom of one molecule is attracted to an electronegative atom of another molecule.

Hydrogen Bonds

The energy required to convert 1 gram of ice to water at 0°C, requiring 80 calories

Latent Heat of Fusion

The energy required to convert 1 gram of water to vapor at 100°C requiring 540 calories.

Latent Heat of Vaporization

A two-phase system with a solid dispersed in a liquid continuous phase, making it pourable.

Sol

Contains 1–4 grains per gallon, lacks mineral salts, and contains some organic matter.

Soft Water

A mixture where small molecules (ionic or molecular) are dissolved in water.

Solution

The process where ice, when subjected to vacuum and then heated, converts directly to vapor without passing through the liquid phase (used in freeze-drying, occurs in freezer burn).

Sublimation

The energy required to raise the temperature of 1 gram of water by 1°C, whether in liquid or ice form (1 cal/g per °C).

Specific Heat

A mixture where molecules larger than those in a solution or dispersion are mixed with a surrounding medium; settles upon standing.

Suspension

The pressure exerted by vapor molecules on a liquid.

Vapor Pressure

The ratio of the vapor pressure of water in a solution to the vapor pressure of pure water.

Water Activity

is abundant in all living things and consequently is in almost all foods, unless steps have been taken to remove it.

water

It is essential for life, even though it contributes ____ calories to the diet.

Water also greatly affects the ______ of foods

texture

It gives crisp texture or turgor to fruits and vegetables and also affects perception of the tenderness of meat.

remember!

Almost all food processing techniques involve the use of water or modification of water in some form: ~freezing ~drying ~emulsification (trapping water in droplets) ~breadmaking ~thickening of starch ~making pectin gels

remember!

Bacteria cannot grow without water, the water content has a significant effect on maintaining quality of the food.

remember!

_______ ______is when vacuoles of plant cells is full of water it exerts pressure to outside of the cell so the walls of the cells of plants are becoming solid and tight making the plant very stiff and rigid.

turgor pressure

Water is important as a ______ or dispersing medium, dissolving small molecules to form true solutions.

solvent

Water is important as a _______ medium, disseminating larger molecules to form colloidal solutions.

dispersing

Acids and bases ionize in water; water also is necessary for many enzyme-catalyzed and chemical reactions to occur, including hydrolysis of compounds such as sugars. It also is important as a heating and cooling medium and as a cleansing agent.

remember!

When modifying the water content of a food, it is necessary to understand these functions in order to predict the changes that are likely to occur during processing of such foods

remember!

CHEMISTRY OF WATER Water contains strong covalent bonds that hold the ____ hydrogen atoms and ___ oxygen atom together.

2,1

CHEMISTRY OF WATER The oxygen can be regarded to be at the center of a ______,The oxygen can be regarded to be at the center of a tetrahedron, with a bond angle of _____°

tetrahedron,105

THE CEMISTRY OF WATER The bonds between oxygen and each hydrogen atom are _____ bonds

polar

THE CHEMISTRY OF WATER Water would be expected to be ___ at room temperature if compared with similar compounds in terms of their positions in the periodic table, but because of the many hydrogen bonds it contains, it is _____.

gas,liquid

THE CHEMISTRY OF WATER _____ is less dense than water because the molecules have a smaller coordination number and cannot be packed together as tightly as water.

ice

THE CHEMISTRY OF WATER Water freezes, its density ________ and its volume increases by about __%

decreases,9

THE CHEMITRY OF WATER Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density

remember!

The specific heat of water is the energy (in calories or in joules) required to raise the temperature of ___g of water by ___ deg C and is the same whether heating water or ice.

1,1

The specific heat of water is __ cal/g per ^ C . This means that it takes ____ cal to raise the temperature of 1 g of water from 0 to 100 deg C

1,100

Latent heat of fusion is the energy required to convert 1g of ice to water at 0 deg C and is ___ cal; that is, 1g of ice at the freezing point absorbs approximately 80 cal as it changes to the liquid state

The latent heat of vaporization is the energy required to convert 1 g of water into vapor at ____ deg * C and is ____ cal; that is, 1 g of water at the boiling point absorbs approximately 540 cal as it becomes steam.

100,540

Both the specific heat and latent heat for water are fairly high compared with most substances, and this is an important consideration when water is used as a medium of heat transfer.

remember!

When ice is subjected to vacuum and then heated, it is converted into vapor without going through the liquid phase. This phenomenon is known as _______.

sublimation

is the basis for the food processing method known as _____-_____.

freeze-drying

The vapor (gaseous) molecules that have escaped from the liquid state exert a pressure on the surface of the liquid known as the ______ _____.

vapor pressure

When the vapor pressure is _____, the liquid _________ (is vaporized) easily and many molecules exist in the vapor state; the boiling point is ____.

high,evaporates,low

The vapor pressure ________ with addition of solutes, such as salt or sugars

decreases

Boiling Point Anything that ______ the vapor pressure (pressure by gas above the liquid) ________ the boiling point.

lowers,increases

One mole of sucrose elevates the boiling point by _.__°C

0.52

One mole of salt elevates the boiling point by _.__° C

1.04

Salts and sugars depress the freezing point of water in a similar fashion.

remember!

Boiling point if the external pressure is ________, for example, at high altitude, water boils at a _____ temperature and so food may require a longer time to cook.

decrease,lower

the ionic bonds are broken, and the individual ions become surrounded by water molecules, or _______.

hydrated

When a hydrogen-bond interchange is involved, solubility increases with increasing temperature.

remember!

Solutes increase the boiling point of water, and the dramatic increase in sucrose solubility with temperature, particularly at temperatures above 100°C (the boiling point of pure water), makes it possible to determine the sucrose concentration by measuring the boiling point of sucrose solution

remember!

FREE, BOUND, AND ENTRAPPED WATER Water that can be extracted easily from foods by squeezing or cutting or pressing is known as____ ____.

free water

FREE, BOUND, AND ENTRAPPED WATER Water that cannot be extracted easily is termed as ______ _____.

bound water

An example of bound water is the water present in cacti or pine tree needles the water cannot be squeezed or pressed out; extreme desert heat or a winter freeze does not negatively affect bound water and the vegetation remains alive. Even upon dehydration, food contains bound water.

remember!

________ water has properties of free water and no properties of bound water.

entrapped

However, microorganisms such as bacteria, mold, and yeast multiply at a ____ water activity

high

WATER HARDNESS AND TREATMENTS ____ ____ contains 1-4 grains per gallon of some organic matter and has no mineral salts.

soft water

WATER HARDNESS AND TREATMENTS ____ ____ contains 11-20 grains per gallon.

hard water

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問題一覧

Water that cannot be easily extracted as it is bound to polar and ionic groups in food.

Bound Water

A mixture where larger molecules than those in a solution are dispersed in a surrounding medium.

Colloidal Dispersion

Strong bonds that hold two hydrogen atoms and one oxygen atom together in a water molecule.

Covalent Bonds

Water that can be easily extracted from food by squeezing, cutting, or pressing.

Free Water

A food-processing method that converts ice directly to vapor without passing through the liquid phase (sublimation).

Freeze-Drying

An elastic solid consisting of a solid continuous phase and a liquid dispersed phase

Gel

Contains 11–20 grains per gallon and is high in calcium and magnesium bicarbonates or sulfates, leading to reduced cleaning efficiency.

Hard Water

Weak bonds between polar compounds where the hydrogen atom of one molecule is attracted to an electronegative atom of another molecule.

Hydrogen Bonds

The energy required to convert 1 gram of ice to water at 0°C, requiring 80 calories

Latent Heat of Fusion

The energy required to convert 1 gram of water to vapor at 100°C requiring 540 calories.

Latent Heat of Vaporization

A two-phase system with a solid dispersed in a liquid continuous phase, making it pourable.

Sol

Contains 1–4 grains per gallon, lacks mineral salts, and contains some organic matter.

Soft Water

A mixture where small molecules (ionic or molecular) are dissolved in water.

Solution

The process where ice, when subjected to vacuum and then heated, converts directly to vapor without passing through the liquid phase (used in freeze-drying, occurs in freezer burn).

Sublimation

The energy required to raise the temperature of 1 gram of water by 1°C, whether in liquid or ice form (1 cal/g per °C).

Specific Heat

A mixture where molecules larger than those in a solution or dispersion are mixed with a surrounding medium; settles upon standing.

Suspension

The pressure exerted by vapor molecules on a liquid.

Vapor Pressure

The ratio of the vapor pressure of water in a solution to the vapor pressure of pure water.

Water Activity

is abundant in all living things and consequently is in almost all foods, unless steps have been taken to remove it.

water

It is essential for life, even though it contributes ____ calories to the diet.

Water also greatly affects the ______ of foods

texture

It gives crisp texture or turgor to fruits and vegetables and also affects perception of the tenderness of meat.

remember!

Bacteria cannot grow without water, the water content has a significant effect on maintaining quality of the food.

remember!

turgor pressure

Water is important as a ______ or dispersing medium, dissolving small molecules to form true solutions.

solvent

Water is important as a _______ medium, disseminating larger molecules to form colloidal solutions.

dispersing

remember!

When modifying the water content of a food, it is necessary to understand these functions in order to predict the changes that are likely to occur during processing of such foods

remember!

CHEMISTRY OF WATER Water contains strong covalent bonds that hold the ____ hydrogen atoms and ___ oxygen atom together.

2,1

CHEMISTRY OF WATER The oxygen can be regarded to be at the center of a ______,The oxygen can be regarded to be at the center of a tetrahedron, with a bond angle of _____°

tetrahedron,105

THE CEMISTRY OF WATER The bonds between oxygen and each hydrogen atom are _____ bonds

polar

gas,liquid

THE CHEMISTRY OF WATER _____ is less dense than water because the molecules have a smaller coordination number and cannot be packed together as tightly as water.

ice

THE CHEMISTRY OF WATER Water freezes, its density ________ and its volume increases by about __%

decreases,9

THE CHEMITRY OF WATER Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density

remember!

The specific heat of water is the energy (in calories or in joules) required to raise the temperature of ___g of water by ___ deg C and is the same whether heating water or ice.

1,1

The specific heat of water is __ cal/g per ^ C . This means that it takes ____ cal to raise the temperature of 1 g of water from 0 to 100 deg C

1,100

100,540

Both the specific heat and latent heat for water are fairly high compared with most substances, and this is an important consideration when water is used as a medium of heat transfer.

remember!

When ice is subjected to vacuum and then heated, it is converted into vapor without going through the liquid phase. This phenomenon is known as _______.

sublimation

is the basis for the food processing method known as _____-_____.

freeze-drying

The vapor (gaseous) molecules that have escaped from the liquid state exert a pressure on the surface of the liquid known as the ______ _____.

vapor pressure

When the vapor pressure is _____, the liquid _________ (is vaporized) easily and many molecules exist in the vapor state; the boiling point is ____.

high,evaporates,low

The vapor pressure ________ with addition of solutes, such as salt or sugars

decreases

Boiling Point Anything that ______ the vapor pressure (pressure by gas above the liquid) ________ the boiling point.

lowers,increases

One mole of sucrose elevates the boiling point by _.__°C

0.52

One mole of salt elevates the boiling point by _.__° C

1.04

Salts and sugars depress the freezing point of water in a similar fashion.

remember!

Boiling point if the external pressure is ________, for example, at high altitude, water boils at a _____ temperature and so food may require a longer time to cook.

decrease,lower

the ionic bonds are broken, and the individual ions become surrounded by water molecules, or _______.

hydrated

When a hydrogen-bond interchange is involved, solubility increases with increasing temperature.

remember!

FREE, BOUND, AND ENTRAPPED WATER Water that can be extracted easily from foods by squeezing or cutting or pressing is known as____ ____.

free water

FREE, BOUND, AND ENTRAPPED WATER Water that cannot be extracted easily is termed as ______ _____.

bound water

remember!

________ water has properties of free water and no properties of bound water.

entrapped

However, microorganisms such as bacteria, mold, and yeast multiply at a ____ water activity

high

WATER HARDNESS AND TREATMENTS ____ ____ contains 1-4 grains per gallon of some organic matter and has no mineral salts.

soft water

WATER HARDNESS AND TREATMENTS ____ ____ contains 11-20 grains per gallon.

hard water