Lecture 2 Flashcards
What are the 5 benefits of cooking food?
- Destroys Pathogenic microorganisms
- Extends shelf life
- Edible and Digestible
- Enhances flavour, texture and overall appeal
- Blanching brightens the colour of green vegetables
What are the disadvantages of cooking food?
Lose vitamins and minerals
Overcooking can lead to unbeneficial results
How do we record heat?
As temperatur
-Thermometer
What kind of heath do thermometers measure?
Sensible heat
How do you convert C to F?
5/9 (temp in F -32)
When calibrating a thermometer what temp would be best to use?
Freezing
- elevation changes the boiling point of water
- ever 900ft you decrease boiling temp by 1 degree C
What are the 2 kinds of pressure?
Atmospheric and Vapour
What is atmospheric pressure?
Downward pressure form the atmospher (gas surrounding the earth)
-higher at lower elevations
What is vapour pressure?
Is the pressure caused by gaseous molecules hovering over the surface of liquid water, as water is heated more gaseous molecules form and increase the vapour pressure
What can increase the boiling point of water?
Pressure cooker
What is the latent heat of fusion?
Heat absorbed when solid–> liquid
-takes 80cals/g
What is the latent heat of solidification?
when heat is released from a liquid–>solid
–takes 80cals/g
What is the latent head of vaporization?
When liquid–>gas
- 540cals /g that is released or absorbed
What is Latent heat of condensation?
Gas to liquid
- 540cals /g that is released or absorbed
What are the 3 dispersions?
- Gas in liquid
- Liquid in liquid
- Solid in liquid
What is a true solution?
The dispersed phase is called the solute and the dispersion medium is referred to as the solvent
-solutes are evenlly distributed throughout the solvent
What is suspension?
Very unstable and composed of large groups of molecules
What is colloidal dispersion?
It is between and true solution and suspension
- dispersed particles are either large or small molecules
- not as stable
- can form gels and sous
What are the 4 kinds of heat transfers?
- Conduction
- Convection
- Induction
- Infrared Radiation
In using a microwave which foods cook faster than others?
High fat and sugar heat more quickly than water
Foods with less density heat faster than high density foods
What is warmed over flavour?
Occurs when foods are reheated via microwave
-polyunsaturated fats are oxidized producing off flavours
How do manufacturers fix warmed over flavour?
Add flavour encapsulation released on heating
Add spices
Releases aromas in heating food
What pros do microwaves have’?
reheating foods quickly
Conserve energy
Reduce amount of nutrients lost
Defrosting
What are the cons of microwaves?
Warmed over flavour
Lack of surface browning
Rehydrate foods
Easy to over cook
Uneaven heating (concerns with food safety)
What are the main components foods are composed of?
Water Carb Fat Protein Minerals Vitamins
What are the 2 bonds in the water molecule?
Covalent: attaches H to O (strong)
Hydrogen: H of one molecule to the O of another (weaker)
-requires lots of energy to bread H2O molecules apart
What is the difference between free vs bound water?
Free: not attached but in cells
Bound: Apart of a molecule structure
What is the equation for water activity?
Vapour pressure of water in food sample/vapour pressure of water of pure water
How do we know when something has a high water content?
Scale 0-1
- The more water that is bound to food, the less activity of the water
- perishable foods have high water activity
What are the 7 functions of water?
- Solvent- dissolves things
- Heat transfer-boiling
- Steaming- preservation
- Freezing- ice cream
- Cleansing Agent
- Chemical Changes- rxns
- Hydrolysis- breaking down links of molecules
What is temporary hard water?
Ca, Magnesium and Iron bicarbonate
What is permanent hard water?
Ca magnesium iron sulphates
What is the difference between the 2 types of hard water?
Temporary: there is a precipitate and it can leave a residue
Permanent: Doesn’t precipitate on boiling but forms a solid. its also unable to remove soaps well
What is the optimal pH range to grow bacteria in?
4.7-5.5
What are the 4 kinds of carbs?
- Monosaccharides
- sucrose, fructose, galactose - Disaccharides
- glucose, maltose, lactose - Oligosaccharides
- 3 to 10 units - Polysaccharides
- more than 10 units
What can oligosaccharides also function as?
prebiotics
-not digestible by humans
What is a complex carb?
Polysaccharide long straight chain or branched of glucoses stuck together
What is the difference between Starch and Glycogen?
Starch: Storage form of glucose in plants:
- amylose (straight)
- amylopectin (branched)
Glycogen: Storage form of glucose in animals
- liver
- muscle tissue
What are amylose and amylopectin used in food for?
amylose: Gelling agent
Amylopectin: thickening
What is fibre?
Long straight chains or long branched chains of glucose molecules
-resistant to digestion and absorption (rough or bulk)
What are the 2 types of fibre?
Insoluble: Just passes through your system (quicker)
Soluble: Thickens by attracting water and helps slow things down
What extras does fibre contain?
Cellulose + hemicellulose: Plant structure
Pectins: Thickening/gelling
Gums: H2O soluble, thickener/gelling. Help stabilize and improve mouth feel
Lignin: Woody parts of food
What are non-enzymatic browning reactions?
Caramelization: When sugar is heated above its melting point
Maillard reaction: sugar and amino acid
- lysine most effective
- browns bread during baking via steam?
What are the 3 types of fat?
- Triglycerides (90-95% of fat in food)
- Phospholipids: emulsifying agent
- Sterols: cholesterol
In TGs what are the components?
Glycerol backbone
3 fatty acids (all same or different)
What are the 2 kinds of cholesterol?
LDL (BAD)- dumps plaque in veins
HDL (GOOD)- scoops plaque up and takes it away
What is a phytosterol?
Sterols from plants which aren’t well absorbed in the intestines and helps impaired cholesterol absorption into the body
What are the different kinds of fatty acids?
Saturated: no DBs
Unsaturated: DBs
- mono
- poly
- cis
- trans
What is the difference between omega 3s and 6s?
3: found in fish and flax seeds
- inflammatory
6 anti-inflammatory
What are the 9 essential amino acids?
- Histidine
- Isoleuicine
- Leucine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
What are complete and incomplete protein sources?
Complete: animal based products and soy and quinoa
Incomplete: most plant based foods
What does it mean when a protein is amphoteric?
it has both acid and base groups (amino and carboxyl)
Why are proteins buffers?
Since they have both acid and base sides, they are able to buffer any major changes in acidity to keep it at a constant pH
What are the 4 types of protein structure?
- Primary- AA chain
- Secondar- A-helix
- Tertiary- 2nd could fold on themselves
- Quaternary- Globular proteins combine with other proteins
What are the 3 things proteins are able to do/be?
Buffer
Denature and Coagulate
Enzymes
What can interfere with food quality?
Acidity and alkalinity which is why buffering is needed to resist the change in pH
What is denaturation?
when the protein molecule unfolds
- becomes less soluble
- enzymatic function is lost
What is Coagulation?
Later stages of denaturation when he denatured protein molecule binds together to form a gel of a solid mass
What are enzymes?
Proteins that act as a catalyst by changing the rate of a reaction without being consumed
What do we classify enzymes as?
Hydrolysis rxns: uses water to break molecules apart
Oxidation/redox: transfer of electrons
What is enzyme function based on?
Temperature
pH
Amount of Substrate
Amount of Enzyme
What happens to enzyme productivity as temp increases?
Activity increases until a certain point at which it is too hot and denaturation of enzyme would occur
