Food Components Flashcards
Water Activity (aw) - A measure of the amount of _______ ____ in foods to: ___________ or _________
and ranges from __ to __
aw<0.85 -> __
adding solute to water _______
available water
be used by microorganisms causing spoilage or
migrate within a food and degrade quality
0 to 1.00
inhibits food spoilage
lowers water activity because water molecules are orientated around the solute and less available for microbial growth
Composition of water
2H+O = H2O
Each water molecule is electrically ________ - ____
Positively charged end ___
Negatively charged end ___
Hydrogen bonds
unsymmetrical - polar
hydrogen
oxygen
1 kilocalorie = ______
Specific heat = ______
The specific heat of water = _____
Because of hydrogen bonding, it takes _____ more energy to heat than any other substance
the amount of water required to raise 1 kilogram of water 1 degree
the amount of heat required to raise the temperature of 1 gram of a substance 1 degree
1.00
water
Freezing point of water:
Heat of solidification:
In water this occurs ______
32 degrees f/ 0 degrees C
The temp at which a liquid converts to a solid
When > or = to 80 calories of heat are lost per gram of water
Melting point of water: ____________
Returning ___ calories of heat to a gram of ice will cause it to reach its melting point
The temp at which a solid turns to a liquid
80
Boiling point of water - heated liquid begins to boil and changes to a gas at ____
Heat of vaporisation: ____
___ calories of energy are needed to boil and vaporise __ of water
The boiling point of water decreases with _____
The boiling point of water increases when we increase the _________
212 degrees f/100 degrees C
The amount of heat required to convert liquid to a gas
540
1g
Elevation
Atmospheric pressure
Solution: completely homogenous mixture of a _____ dissolved in a ______
Colloid solution: dispersion in which the particles are ____ nm to ___ microm in diameter and therefore too ____ to go into a solution but not ____ enough to precipitate out of the continuous phase
Suspension: dispersion in which the particles are _______ than the ___ microm diameter and remain suspended in the continuous phase
solute
solvent
2
1
large
large
larger
1
Acid-base reactions (availability of __ and __)
Salt formation (__ + __ -> ___)
Hydrolysis (_____ -> _____)
Condensation (_____ -> _______)
CO2 release (____+ ___ & ____)
H+ & OH-
Na+ + Cl- -> NaCl
corn starch -> corn syrup
monosaccharides -> disaccharides
baking soda + acid & water
Carbohydrate functions
Sweetness
Colour/Browning
Texture/Volume
Alcohol source
Preservation
Relative sweetness of monosaccharides and disaccharides
Glucose -
Fructose -
Galactose -
Maltose -
Sucrose -
Lactose -
50
150-180
26
40
100
20-40
Functions of Proteins in foods
Hydration
Browning
Denaturation/Coagulation
Enzymatic reactions
Buffering
Thickening
Functions of Lipids in foods
Heat Transfer
Tenderness
Emulsification
Texture
Flavour
Vitamins:
- _____ molecules
- ______ complex molecules
- provide ____ to food
- cooking process impact ______
- Vitamin _ used as an additive
organic
large
colour
retention
C
Minerals:
- ________
- ____ ____ has multiple roles in food preparation:
____, ______ & ______
- iron, calcium and sulphur also have specific food chemistry implications
inorganic
sodium chloride
- flavour
- food preservation
- role in food processing e.g. cheese and bread
Carotenoids - ____
Chlorophyll - _____
Flavonoids - _____
carotene, lycopene and xanthophyll
a & b
anthocyanins, anthoxanthins and betalains
Carotenoids:
______ affects the colour of plant foods
exposure to ____ also causes _____ of pigments and a resulting loss in colour
vegetables containing b-carotene should not be _____
heat
oxygen
oxidation
overheated
Chlorophyll:
- pigment responsible for ____ colour of plants
- essential for _______
- _________ enhances the _____ colour by removing the air bubbles which may cloud the colour
- not very ____ need to: keep heating times ____ and heat food _____ initially to allow for the escape of _____ organic acids
- dull olive brown when overcooked comes from the ____ coming into contact with the _______ as the membranes are disrupted
green
photosynthesis
blanching
green
stable
short
uncovered
volatile
acid
chloroplasts
Pigment that is responsible for the colour of the following:
cauliflower
kale
tomatoes
pineapple
beetroot
pumpkin
zucchini
- anthoxanthin
- chlorophyll
- lycopene
- xanthophyll
- betalains
- carotene
- anythocyanins
what factors will reduce the water activity of food?
Addition of sugar
Addition of salt
Sun-drying
Baking
what food chemistry reactions involves water as a key function
hydrolysis
salt formation
condensation
carbon dioxide release from baking soda
which of the following factors will lead to an increase in the boiling point of water?
addition of sugar
boiling water at a higher elevation
addition of more heat
use of a slow cooker
addition of water
