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Food Science Ch 3
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Undergraduate 3
09/09/2010

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Term
What are nutrients?
Definition
food components that nourish to provide growth, maintenance and repair
Term

What are the 6 basic nutrients

 (that most foods consist of)?

Definition

water, carbs, lipids, proteins, vitamins and minerals

 

* the purpose of eating and drinking is to replace nutrients used up

Term
What is biochemistry?
Definition
the study of chemistry that occurs in living organisms
Term
All living things contain 6 key elements...
Definition
carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur-    CHNOPS
Term
Where do calories come from?
Definition
carbs, protein, fat, and alcohol
Term

How much water is in the body?

 

 Necessary for?

Definition

60-70 %

 

-it is the simplest of all nutrients, and most important

 

-necessary for: assimilating, digesting, absorbing, transporting, metabolizing, and excreting

 

Term
Food has a water content of ?
Definition

0-95%

 

fruits/ veggies= 70-95%

whole milk= 80%

most meat= under 70%

Term
What are the 2 types of water?
Definition

Free water= largest amt and easlily seperated from food

 

Bound water= incorporated into food- not easily removed

Term
What is the composition of water?
Definition
1 atom of oxygen and 2 atoms of hydrogen
Term
How do you measure water?
Definition

in the form of calories once heated

 

"C" = raising 1 kilogram of water 1 D Celcius

 

one kilocalorie (kcal)= 1,000 calories

Term

Molecular movement dictates whether a substance is ...

 

-explain

Definition

:solid, liquid or gas

 

solid= ice , water molecules line up closely

 

liquid= water, they move away from each other

 

gas= steam, water moves away far enough to escape

Term

What is waters freezing point?

 

and what happens?

Definition

32 d F/ 0 d C at normal atmospheric pressure

 

-when temperature at which liquid turns to solid

Term
When does heat solidification occur?
Definition

when at least 80  calories are lost per gram of water

 

-water expands and becomes less dense when frozen

Term

What is waters boiling point?

 

and what happens?

Definition

212 d F (100d C) at sea level:

requires 540 calories to boil or vaporize

 

temperature at which liquid begins to boil

 

-after point is reached additional heat will not increase temp or cook food faster

Term
What is heat vaporization?
Definition
the amt of heat required to convert liquid to a gas
Term
What minerals determine soft water?
Definition
higher sodium content
Term
What minerals determine hard water?
Definition
more calcium and magnesium
Term
What are the 2 most important functions of water in food?
Definition

transfer medium for heat,

and its a universal solvent

 

-additional= agent in chemical reactions, and factor in perishability and preservation of foods

Term
What is specific heat?
Definition

heat required to raise the temperature of 1 gm of a substance 1d C

 

-water takes most energy of heat than any other

Term
When happens at melting point?
Definition

a solid turns to liquid

 

-latent heat= amt of energy per gm absorbed or emitted as a substance changes states

Term
2 most important functions of water in food:
Definition

1. its a transfer medium for heat

=transfers and moderates heat more efficiently

 

2. universal solvent

Term
Heat transfer methods (3):
Definition

1. moist-heat cooking method= 1/2 of cooking methods use water to transfer heat

ex: boiling, simmering, steaming

 

2. dry-heat method= use heat in radiation form

ex: baking, grilling, frying

 

*microwave uses both moist and dry heat, radiation heats water in food, which heats food

Term
water- 4 Universal solvents
Definition

solvent= usually a liquid, when a substance is dissolved

 

solute= solid, liquid or gas disolved in another substance

 

solubility= ability of substance to blend uniformly with another

 

solution= homogenous mixture of a solute(solid) dissolved in a solvent(liquid)

Term

notes:

biochemical interactions could not occur in absense of solvent environment

 

combining a solvent and solute creates a solution, a collodial dispersion, suspesion or an emulsion

Definition

notes:

molecules of solute completely dissolve and will not precipitate out from medium

 

 

Term
When might nutrients be lost?
Definition
when cooking in water
Term
more solute to dissolve in solvent- creates a saturated solution
Definition
higher heat
Term
what is created with higher heat? very unstable. must be cooled slowly to prevent seperation
Definition
supersaturated solution
Term
solvent containing large particles that go into solution but too large to come out
Definition
collodial dispersion
Term

notes:

colloids= ex: proteins, starches, fats

 

dispersions= ex: liquid in a solid

liquid in another liquid

liquid in a solid

gas in a liquid

gas in a solid

 

Definition

notes:

food preservation=

water is important for the life of microorganisms that affect food- bacteria, yeast, mold

 

decay is formed when humidity and heat combine, promoting their growth

 

if water is cool, it can preserve foods life

-more water available= spoilage

Term
2 types of dispersions:
Definition

suspension= particles too large to go into solution

 

emulsion= liquid dispersed into another liquid

Term
When particles dissolve in solvent, solution is either...
Definition

molecular= when dissolved particles remain "as is"

 

ionic= when solute moleules ionize into electrically charged ions

Term
What is the pH scale and what is it used for?
Definition

measures the degree of acidity or alkalinity of a substance, with 1= most acidic

7= neutral

14= most alkaline

Term
What happens in hydrolysis?
Definition
a chemical reaction of 2 or more substances being broke apart by water
Term
When you combine water and baking soda what is released?
Definition
carbon-dioxide
Term

What is osmosis?

 

What is osmotic pressure?

 

 

Definition

movement of a solvent through a membrane to the side with the higher concentration= equalizing it

 

two solutions of different solute on either side pull

Term
Foods high in carbs:
Definition

sugars, starches, fiber, plants= seeds, roots, stems, fruits

 

most common= grain, fruits, beans

Term
composition of CHO:
Definition

C- Carbon

H-Hydrogen

O-Oxygen

 

-found in green plants where synthesized via photosynthesis

Term
Simplest sugars
Definition

monosaccharides

 

classified by # of carbons=

 

triose= 3 carbons

tetrose= 4 carbons

pentose= 5 carbons (most common)

hexose= 6 carbons (most common)

 

Term
most common hexose found in foods
Definition
glucose
Term
where is fructose found?
Definition

fruits/ honey

 

-its the sweetest of all sugars and hardly ever used

Term
3 types of Disaccharides:
Definition

sucrose= table sugar- 1 glucose mol /1 fructose mol

 

lactose= 1 glucose mol/ 1 galactose mol

 

maltose= 2 glucose mols

Term
How many monosaccharides do oligosaccharides have?
Definition

3 to 10

 

the most common=

raffinose= 3 monos

stachyose= 4 monos

 

(are found in dried beans, not well digested)

Term

Most common polysaccharides:

 

2 groups?

Definition

starch, glycogen, and fiber

 

 

 

are divided into 2 groups=

 

digestible= starch and glycogen

 

indigestible= fiber

Term

notes:

 

starch= digestible polysaccharide from plant source, glucose derived from photosynthesis is stored as starch, body can break down for absorption

 

glycogen= digestible polysaccharide from animal source, stored in animal bodies, is also converted to lactic acid

 

fiber= indigestible polysaccharide, fiber are held together by bonds that cant be broken down and do not provide energy, found only in plants

Definition

2 types of Fiber:

 

dietary fiber

crude fiber

 

soluble fiber= dissolves in water

insoluble fiber= does not dissolve

Term
3 Common fibers
Definition

cellulose

hemicellulos- a mixture of monosacc

pectic substances- found in cell walls of fruits/veggies

 

 

Term
A type of polysaccharide
Definition
vegetable gum- composed of simple sugars, gum fibers
Term

notes:

Inulin= repeating units of fructose with an end molecule of glucose

 

Lignin= one fiber that isn't CHO, produces tough stringy texture in food-ex: carrots

 

* see veggie/plant pics in book-

 

Definition
Term
Some functions of CHO in foods:
Definition

sugars provide sweetness, color, texture, preservation

 

starches provide thickening agent

Term
What are lipids called in foods?
Definition

"fat"

 

fats and oils belong to the lipid group

 

2 differences:

fats are solid at room temp

oils are not

Term

Foods high in lipids/fat

 

Definition

animal sources= meat, poultry, dairy

 

plant sources= nuts, seeds, avacado

 

-fruits/veggies are low in fat

Term

notes:

 

invisible fat- not easily seen= marbling in meat

 

visible fat- bacon white stripes

Definition
Term
Composition of lipids
Definition

carbon, hydrogen, oxygen

 

not water soluble

Term
3 groups of edible lipids:
Definition

triglycerides= @ 95% of lipids, have 3 fatty acids

 

phospholipids= 1 fatty acid is replaced with phosphorus compound

 

sterols= large, interconnected rings of carbon

 

 

 

 

Term
Most common fatty acids found in butter:
Definition
butyric acid, linoleic acid, linolenic acid
Term
Functions of lipids in foods:
Definition

tenderness, heat transfer, flavor, increases satiety,

 mixing (emulsifying)

Term
What are sterols found in the body?
Definition

cholesterol, bile, testosterone, esrogen, adrenal hormones, vitamin D

 

found in both plants and animals

Term
Functions of proteins:
Definition
hydration, denaturation, coagulation, enzymatic reactions, buffering, browning
Term

notes:

 

hydration= ability of protein to dissolve and attract water

 

denaturation= protein structure disrupted

coagulation= clotting or percipitation of protein

(both irreversible)

 

enzymatic reactions= enzymes are catalysts that speed up chemical reactions, composed of protein/non-protein, only operate under mild pH

Definition

notes:

buffering= resist extreme pH shifts

 

browning (2)=

-maillard reaction: the reaction betwn a sugar/protein

-enzymatic browning: an enzyme acts on a phenolic compound causing browning

Term
Foods high in vitamins/minerals:
Definition

meats- vit B,iron, zinc

dairy- calcium, eggs- vit A,D,E,K

plants- vit C

fermented foods- vit B12

processed foods- Na

Term
2 major vitamin groups
Definition

fat soluble- A,D,E,K

 

water soluble- B complex, C

Term
2 mineral groups
Definition
macro and micro
Term
composition of vitamins
Definition
organic compounds
Term
composition of minerals
Definition

inoganic elements

 

-can not be destroyed by heat,light, or oxygen

Term
2 Functions of vitamins/minerals
Definition

enrichment= adding nutrients lost during production

 

fortification= nutrient added that were not originally present

Term

A compound that inhibits oxidation

and causes deterioration and racidity

Definition

antioxidants

 

note- important antioxidants= vitamin A,C,E and mineral selenium

 

uses= neutralizes free radicals

Term
Only mineral directly consumed
Definition

sodium

 

uses- preserative, enhances flavor

Term
A substance added to food so that it affects its characteristics
Definition

food additive

 

-there are over 30,000

 

ex: citric acid, baking soda

 

purpose- improve appeal of foods(smell, flavor, texture, color), extend storage life, maximize performance, protect nutrient value

 

Term
Plant compounds benefits/ harmful
Definition

phytochemicals- have a protective effect against cancer

 

moderate intake of caffeine causes physical/ psychological problems

Term
molecules and compounds combine to create
Definition
all substances on earth
Term

notes:

elevation and boiling point=

as altitude increases, boiling point decreases,

occurs when there is less air and atmosph pressure pushing down, steam is faced with less resistence

Definition
Term
3 Fatty acid structures
Definition

saturated= no double bonds betwn carbons

 

unsaturated= 1 hydrogen missing betwn 2 carbons

 

monosaturated= 1 double bond is present

 

polyunsaturated= 2 or more double bonds are present

 

-the higher the unsaturation the more likely fat is liquid at room temperature, most foods contains all 3 types of fatty acids

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