Final Exam (Chapters 4-6) Flashcards
What is the most abundant molecule in food?
Water (H20)
Almost all foods contain what?
Water
What is polarity?
An atom / molecule that exhibits opposite powers in opposite directions
Is water polar?
Yes
What is solubility?
The ability to be dissolved (especially in water)
What are the substances called that easily dissolve in water?
Hydrophilic (hydra - fill - lick)
What are the substances called that don’t easily dissolve in water?
Hydrophobic (hydra - phobe - ic)
What is boiling point?
The temperature where vapour pressure = atmospheric pressure
What is water’s normal boiling point?
100 degrees celcius
Why does water boil at lower temperatures at higher altitudes?
Since vapour pressure = atmospheric pressure, when you increase your altitude (go higher) there is less atmospheric pressure… therefor there is less vapour pressure required to get to boiling point
What happens to the boiling point of water when salt is added to it?
The boiling point will increase (aka it will need to be a bit hotter to boil)
What happens to the boiling point of water when sugar is added to it?
Adding sugar will raise the boiling point of water. This means that the water will need to be a little bit hotter than 100 degrees to boil, therefor food will cook a little bit faster due to the higher temperature
What is freezing point?
The temperature at which a liquid becomes a solid
What is pure water at sea level’s freezing point?
0 degrees Celsius
At which temperature is water its most dence at?
4 degrees celsius
Water is the only molecule that is ____ at a frozen state than at a liquid state.
less dense
What does solutes (sugar…) do the waters freezing point?
lowers the freezing point of water
what happens to the ice crystals when they are fast frozen?
the ice crystals are smaller (less chance to migrate)
what happens to the ice crystals when they are frozen slowly?
the ice crystals are bigger (more time for them to migrate)
What size of ice crystals do you want?
you want smaller ice crystals because you can taste bigger ones
What temperature should you never thaw your food in?
Room temperature
What is freezer burn
it is dry and burnt in places
cannot hold onto the juices
texture is awful
What is the best way to thaw food?
move it from the freezer to the fridge
put the item in cold tap water (must change water regularly to keep temperature low)
What is water activity?
the partial vapour pressure of water in a substance divided by the partial vapour pressure of water at that same temperature
aka vapour pressure of the water in the food compared to vapour pressure of pure water
What is the consequence if you reduce the amount of water activity in a food?
you prolong the shelf life of that item
(make the shelf life longer)
what water activity level will cease the growth of all microorganisms?
0.6
What does low water activity do?
Inhibits microbial growth
also provides crispness and crunchiness textures (snack foods and cereals)
What does highest specific heat mean?
it can absorb and lose the most heat when temperature increases or decreases by 1 degree celsius
What liquid has the highest specific heat than all known liquids?
Water
What does high specific heat do in regard to cooking?
Contributes to faster cooking
What cooks food faster, food boiling at 100 degrees or in the oven at 100 degrees Celsius?
food boiling at 100 degrees celsius cooks food faster.
because dry heat has much lower specific heat than water
What is osmosis?
Water moving from higher concentration of solutes to lower concentration of solutes
What is the fluid in a cell maintained by?
a phenomenon known as osmosis
what does the crispiness of vegetables and fruits depend on?
the osmotic pressure of their cells
What helps prevent fruits from losing water (why would this be a good thing)
many fruits are coated with wax that seals the pores on the fruit to prevent evaporation
this helps keep the crispness of fruits (keeps the fruit’s osmotic pressure)
How are carbohydrates formed?
in green plants through photosynthesis, the suns energy converts carbon dioxide from the atmosphere and water from that soil into glucose
What are carbohydrates?
Hydrates of carbon
Thus made up of carbon, hydrogen, and oxygen
What does photosynthesis produce?
glucose
what are the carbohydrates classified as (the ones produced from glucose from photosynthesis)
sugars:
monosaccharides
diaccharides
oligosaccharides
What is a saccharide
A sugar molecule
How many sugars is a monosaccharide?
one sugar molecule
what is glucose an example of?
A monosaccharide
Are monosaccharides sweet in taste?
yes
how many sugar molecules are in disaccharides?
two sugar molecules
are disaccharides also sweet like monosaccharides?
yes
What is an example of a disaccharide?
Lactose
Is lactose intolerance an allergy?
No, its a sensitivity
What is used as a reference for sweetness?
Table sugar
What are humectants?
substances that hold moisture in foods?
what is an example of humectants?
sugars
What is caramelization?
When sugar is dry heated at high temperatures, the sugar melts and turns brown (caramelization)
Leads to brown colour plus caramel flavours
What is maillard reaction?
a reaction between reducing sugar (all monosaccharides and most disaccharides), and an amino acid
when heated they react and lead to the complex mixture of brown compounds called melanoidins
This is the colour, flavour, and aroma of baked bread
Does sugar increase the freezing point?
No, it reduces the freezing point
the higher the concentration of sugar, the lower the freezing point
What does sugar also reduce in frozen foods?
It reduces the risk of large ice crystals forming in frozen desserts
What are oligosaccharides?
3-10 sugar molecules connected
Are oligosaccharides water-soluble?
yes
What can oligosaccharides lead to an excessive amount of?
gas
This happens in beans
Why do oligosaccharides cause so much gass?
Becuase humans cannot digest oligosaccharides due to the lack of enzymes. so they just pass through humans and go out as gas
How can you get rid of oligosaccharides in beans?
Soaking them in tap water before cooking the beans
What is butter (oil in water emulsion, or water in oil emulsion)?
Water in oil emulsion
What are polysaccharides?
complex carbohydrates that contain 10+ (typically hundreds) of sugar molecules connected
What are examples of polysaccharides?
Starches, fibers, and glycogen
Does starch have an odor?
No, it is odorless
Is starch soluble in water?
No starch is insoluble in water
What are the starches called that contain no amylose?
Called zero-amylose or waxy starches
What are sources of starch?
Plant foods (potatoes, yam, cereal grains, beans…)
What does starch provide lots of for very cheap?
Starch provides lots of energy for very cheap
What is starch used for in food?
used as a thickener in food
in soups and gravies
also great at binding for meat or plant patties
What is dextrinization?
when starch is heated in the absence of water, the starch breaks down and becomes sweeter, has flavour, color, and aroma
It also reduces starches ability to form a gel
What is glycogen?
a polysaccharide (hundreds / thousands of glucose molecules)
highly branched, not linear
humans do produce enzymes to break these down
What does glycogen provide energy to that nothing else does?
Our brain receives its only energy from glycogen
What is dietary fibre?
a polysaccharide that is part of plant material
our digestive system doesn’t produce the enzymes to break these down
What is the definition of water-soluble fibres?
Dissolve in water and increase the viscosity of the water. Leads to slow movement through our digestive system, this keeps our stomach full for a longer period of time
it also slows down the absorption of nutrients which prevents sharp increases in glucose levels
Is it true that water-soluble fibres increase the chance of heart diseases?
No, in fact they may reduce the risk of heart diseases by lowering the blood cholesterol levels
What are sources of water-soluble fibres?
Beans, vegetables, fruits, and some cereal grains (oats, barley, rye)
What is the definition of water insoluble fibres?
they do not dissolve in water and have no impact on the viscosity of the water
Where are insoluble fibres found in foods?
Are present on the outer layers of all plant foods (fruit peels, vegetables, whole grains, beans…)
what can you add to improve the texture of foods?
soluble fibres retain water in the baked goods, therefore slowing things down (somehow good for improving the texture)
Can fibres add colour?
Yes, insoluble fibres are bound to many colour compounds
What are lipids?
they are organic macromolecules that are generally insoluble in water, but are soluble in non-polar solvents (like alcohol)
What are lipids broadly classified as?
They are broadly classified as fats and oils
Where do fats come from?
Most animal foods contain lipids (beef, chicken, turkey, pork…)
Are fats solid or liquid at room temperature?
solid
Are oils solid or liquid at room temperature?
liquid
What are sources of oils?
most plant lipids come from canola, olives, sunflower seeds…
What are lipids broadly classified as?
triglycerides, phospholipids, and sterols
what are triglycerides?
a classification of lipids
the major form of dietary lipid in fats and oils
95% of all lipids in nature are triglycerides
What does it tell you when the more solid a lipid is at room temperature?
the more saturated fatty acids it contains
What is high intake of saturated and trans fat linked to?
Heart diseases
Why does Canada food guide recommend replacing some of the animal based protein foods with plant based protein foods?
Because food sourced from animals / processed foods increase our intake of saturated and trans fat, which increases our risk of heart disease
What are phospholipids?
they have two fatty acids and phosphorous molecule attached to glycerol molecule
What kind of unique property do phospholipids have? And why do they have it?
The unique property is that it binds fats and water which would otherwise be immiscible
This is because fatty acid chains are hydrophobic (don’t easily dissolve in water) and phosphorous is hydrophilic (easily dissolves in water)
What is am emulsifier?
It is a substance that can keep two immiscible states mixed
two things that don’t want to form a homogenous mixture together
What do phospholipids act as?
emulsifier
What are sterols?
they are a class of lipids
containing a common steroid core with a hydrocarbon side chain and an alcohol group
What is the most common form of steroid in animals?
cholesterol is part of all animals cells
Is margarine better than butter in regards to health?
Hydrogenated margarine is worse than butter
non hydrogenated margarine is equal to butter
What oil is ideal for cooking with?
Canola oil has almost no saturated fat, it is cheaper, and it has a higher smoke point
don’t use olive oil because it’s higher in saturated fats and has a lower smoke point
What is smoke point?
Smoke point aka burning point is the temperature where an oil or a fat starts producing a steady stream of smoke
it can’t be heated beyond that temperature
Why do foods cook faster when fried in hot oil or fat than in boiling water?
Because oils and fats can be heated to a much higher temperature than water (many can go above 200 degrees Celsius) while water’s boiling point is 100 degrees Celsius
Does Canada have safe food supply?
Yes, Canada has one of the safest food supplies in the world
How many people each year in Canada gets sick from contaminated food?
4 million (1 in 8 people)
What is the definition of a hazard?
Anything that has potential to cause harm
What are the types of hazards in food?
Physical - physical injury
Chemical - toxicity to organs and tissues
Biological - foodborne illness
What are some ways in which chemical hazards can enter food?
Additives - chemicals intentionally added to the food to enhance the quality
Adulterants - chemicals intentionally added to the food to deceive the consumers (this is a criminal offence in Canada)
Residue - chemicals that are used in the food process, but not intended to be a part of the food
Contaminants - chemicals where the food was unintentionally exposed
What is the difference between additives and adulterants (chemical hazards)
Chemical additives are used to enhance foods quality, chemical adulterants are used to deceive the consumers (intentionally)
What is solanine (chemicals naturally found in food)
produced by plants as a natural fungicide and pesticide
green parts, sprouted potatoes, leaves of tomatoes and potatoes have high levels of solanine
Cannot be destroyed by heat (heat stable)
Where can glucosinolate be found (naturally occurring chemicals present in food)
present in rapseed, cabbage, cauliflower, brussel sprouts, broccoli… list goes on
high temperatures kill these substances
What are characteristics of psoralents?
present in celery, parsnip, especially in damaged tissues
can cause cancer in high doses
Heat sensitive (cooking kills)
What is acrylamide (toxins produced while processing / cooking food)
created when starch and an amino acide combine during high temperature cooking for an extended period of time
may cause cancer
avoid over cooking starchy foods like burnt toast or dark brown fries / chips
What are food additives?
natural and synthetic chemicals permitted by the government to be added to food
Does the government regulate the use of pesticides or other chemicals used? (If yes, what do they control?)
Yes, they specificy the max amount you can use, plus what time periods you are allowed to use them to make sure you dont use them up until harvesting the crops
Are the residue of chemicals 0 (non existent) for organic foods?
no
they can be transfered through the air (by joint fields), natural chemicals are still allowed to be used for organic foods (man made chemicals are not allowed)
What does pathogenic mean?
Disease causing
If a food smells bad (past its best before date), is it always harmful?
No, some bacteria just smell bad but aren’t harmful
However, some bacteria won’t smell bad but will be harmful after the best before data
What percent of bacteria is pathogenic (disease causing) to humans?
4% of known bacteria
If my friend doesnt get sick from eating expired food, that means i wont get sick either.
False
What can cause foodborne illnesses?
Food with disease causing (pathogenic) microbes can cause foodborne illnesses
What is an infection (foodborne illness)
When microorganisms multiply and invade our tissues and organisms, resulting in getting sick
What is the difference between infections and intoxication (foodborne illnesses)
Infections are when live bacteria is ingested and leads to us being sick
Intoxication is when we eat food that contains a toxin that was produced by a bacteria
Can toxins cause serious damage?
Yes. if defences fail, toxins can cause damage to your liver, your brain…
How long do symptoms usually take to appear after ingesting intoxicated food or infectous food?
Symptoms from intoxication can appear within 24 hours of eating the food
Symptoms from infections / mediated toxin infections can take 24-72 hours (or even longer) to appear
what ph level do few microorganisms grow in?
below 4.0 ph
What is the best ph value for microorganisms to grow in?
values around 7.0 ph are best for microorganisms
What level of water activity do most harmful bacteria need to grow?
At least a 0.9 water activity
What level of water activity can no microbial growth occur at?
below a 0.6 water activity
What is the optimal growth temperature for microbial growth?
4 - 60 degrees celsius is called the danger zone.
What is the maximum temperature microbial growth can happen at?
Some can survive temperature that are higher than 100+ degrees celsius
Does microbial growth need oxygen to grow?
Not all no. Some can only grow if there is oxygen, some can only grow if there isnt oxygen, some can grow in both but one is more ideal
What does it mean when a microbe is obligate aerobe?
It means this microbe cannot grow in the absence of oxygen (it needs oxygen to grow)
What does it mean when a microbe is obligate anaerobe?
Microbes that cannot grow in the presence of oxygen
(cannot grow with oxygen)
What does it mean when a microbe is facultative anaerobes?
This microbe can adapt from aerobic (oxygen available) to anaerobic environment (oxygen not available)
They do prefer / it is optimal that they grow in the presence of oxygen
What does it mean when a microbe is facultative aerobe?
Can adapt between no oxygen and with oxygen
Grows better in the absence of oxygen
Where do chemotrophs obtain their energy from?
From chemicals (organic and inorganic)
Where do autotrophs get their energy from?
they produce their own energy (food) from carbon dioxide
What is the difference between chemotrophs and autotrophs
Chemotrophs obtain their energy from chemicals
Autotrophs produce their own energy from carbon dioxide
If the surface area of food is higher, what happens to the growth of the microbe
It increases (the higher the surface area, the faster the microbe will grow)
Can produce carry hazardous microbes? What did we used to think?
Yes, produce (vegetables and fruit) can carry hazardous microbes.
Due to the increase in globalization and increase in potential for cross contamination… produce has now evolved to be a risk for hazardous microbes (when it was thought years ago that these microbes don’t grow on produce)
What are ways to prevent cross contamination?
Being mindful of sharing cutting boards, utensils
Make sure to store meat on the lowest shelf (so it doesnt drip juices)
Wash hands
What is salmonellosis?
it is an infection caused by bacteria
What are symptoms of salmonellosis?
Diarrhea, fever, vomiting, and abdominal cramps 12-72 hours after infection
How do you kill the microbes that can cause salmonellosis?
by cooking food to high internal temperatures, this would kill all potential hazardous microbes
How do you properly take the internal temperature of meat, why is this important?
You want to make sure that the thermometer is in flesh and not by bones, as bones can heat up very quick
This is important to ensure the entirety of the meat is cooked and all potential hazardous microbes are killed (due to the high temperature)
What is botulism?
A common foodborn illness that is produced by the bacteria clostridium botulinum
How do you destroy clostridium botulinum (the bacteria that causes botulism)
In temperatures higher than 116 degrees Celsius, the bacteria also cannot grow below a PH of 4.6
How much do you have to consume of botulism for it to cause illness / be fatal?
An extremely small amount
What is one of the most potent toxins we know of?
Botulism
What are the physical symptoms of Botulism?
double vision, droopy eyelids, difficulty speaking / swallowing, difficulty breathing, paralysis, can lead to death
Who is most as risk for listeriosis?
pregnant women, new born infants, people with weak immune systems, people who are 65+
What is listeriosis? (where can it be found)
an infection caused by bacteria that is present in soil, water, and feces
What foods are risky for listeriosis?
raw sprouts, raw milk, soft cheeses, deli meats and hot dogs (that are not heated but served cold), smoked seafood
Where is escherichia coli (E. Coli) found?
In the gut of humans and warm blooded animals
What are the symptoms of E. Coli?
diarrhea
How is E. Coli transmitted?
through the consumption of contaminated foods (raw or uncooked meat products, raw milk, contaminated raw vegetables)
What is food processing?
any operation carried out on raw food is called a process, which results in a processed food product
What are the reasons for processing food?
Preservation (extend the shelf life)
Make food edible
Enhance nutritional quality
Make food more convenient to consume
Price reduction (reduction in wastage)
What does asepsis mean?
means keeping out the microorganisms
how do you slow the growth of microorganisms?
Microbes need a certain level of water activity, ph level, temperature, oxygen level… to multiply / grow. If one of these conditions are changed, the growth rate declines and the shelf life is extended.
What is pasteurization?
the application of heat to a food product in order to destroy pathogenic (disease causing) microorganisms
the higher the temperature, the shorter the time needed to kill microorganisms
What is sterilization?
Killing all the microorganisms in the food
What is the goal of canning?
Destroy almost all the microbes so that 1 in a million cans have a microbe cell
How does canning prevent microbes from growing?
No microbes can enter the can (airtight seal)
lack of oxygen
Thermal heat treatment
What is the process of blanching?
briefly dipping the food (typically vegetables and fruits) in boiling water followed by cold water
What is the purpose of blanching?
a heat treatment to inactive enzymes in food, which would otherwise deteriorate the food quality
What is dehydration?
the removal of water so that microbial growth is pervented
What is sun drying? (dehydration)
Least controlled method (cannot control the sun light temperature or humidity)
Takes the longest time
What is plate drying? (dehydration)
food is placed on trays and heated in a hot chamber
moist air is let out
What is drum drying? (dehydration)
What is its primary use?
Primary use is for dehydrating viscous fluids for powder
What is drum drying? (dehydration)
What is its primary use?
Primary use is for dehydrating viscous fluids for powder
What is spray drying? (dehydration)
atomizing milk into droplets in a hot chamber by spraying them, they dry before they hit the bottom of the chamber
What is freeze drying? (dehydration)
food doesnt need to be heated (so little damage to the nutrients)
99% of water can be removed by this method
What is freeze drying also known as? (dehydration)
Lyophilization
What percent of all vegetables and fruits grown are wasted?
45%
What is refrigeration? (food preservation methods)
the cooling of food between 0-4 degrees Celsius to slow down microbial growth
What is freezing? (food preservation methods)
cooling foods to below 0 degrees Celsius to freeze the water in the food. the frozen water in the food doesn’t allow microbes to grow
How would you change the PH of food?
Addition of acids such as acetic acid, vinegar, citric acid
For example: pickles
Where does the majority of sodium come from in our diet?
Processed foods
What does high blood pressure increase your chances for?
Heart attacks and strokes
What is irradiation?
exposing food to ionizing radiation
(gamma rays, electron beams, x rays
They destroy any biomolecules that they come in contact with
What are the different materials used in packaging?
Glass, metals, paper, plastic
What are fruits called that continue to ripen after harvest?
Climacteric fruits
What are examples of controlled or modified atmospheric packaging?
Bags of chips are filled with nitrogen gas to prevent rancidity
Gas flushed meat packaging
What are the four different classes of chemical preservatives?
Class 1 - curing preservatives
Class 2 - antibacterial
Class 3 - antifungal & antimycotic
Class 4 - antioxidants
What is staphylococcus aureus?
a common bacterium found on the skin and noses of 25% of healthy people and animals
What is the most common way for food to be contaminated with staphylococcus?
through contact with food workers who carry the bacteria or through contaminated milk and cheeses
Can staphylococcal toxins be destroyed by cooking (heat)?
No it is unaffected by heat
What is the most common foodborn illnesses / viruses called?
Norovirus
What is another name for the norovirus?
The cruise ship illness
What is prions disease?
a type of protein that can trigger normal proteins in the brain to fold abnormally
What is mad cow disease an example of?
It is a branch of prion diseases, specifically mad cow disease is called variant Creutzfeldt-Jakob disease (vCJD)
What are symptoms / affects of prions diseases?
can cause memory impairment, personality changes, difficulties with movement, they are also generally fatal
How many gmo foods have been approved to be sold in canada?
140
What is the food category “novel foods”
a food group the consists of the 140 gmo foods that are allowed for sale in canada
Is it a law to disclose if a product contains gmo ingredients?
no not in canada
What are proteins made out of?
Chains of amino acids linked together with peptide bond
What is the primary structure of a protein?
the primary structure is a linear structure and indicates the sequence of amino acids in the chain
What is the secondary structure of a protein?
The backbones of amino acids in a polypeptide chain form hydrogen bonds with one another, leading to the folding of the chain. (turns into a two dimensional structure)
What is tertiary for proteins structure?
When side chains of amino acids interact with one another and lead to the folding of alpha-helix or beta sheets (the secondary structure shapes)
The folding turns them into 3-dimensional shapes, which is critical to protein’s functionality
What are the two most common two-dimensional structures proteins form into in the secondary structure stage?
Alpha-helix & beta sheets
What is the Quaternary structure of proteins?
subunits of 2 or more polypeptide chains, the interactions between these subunits results in a unique shape of the protein
The quaternary structure is proteins that are made from multiple polypeptide chains
What is denaturation of proteins?
the reversible or irreversible change in protein shape
What are some denaturation agents?
Ph change, heat, alcohol, uv radiations, heavy metals
What is a proteins isoelectric point?
the ph at which a protein has net zero charge, the number of positive and negative charges equal
At what point are proteins least soluble and has the lowest water holding capacity?
When proteins are at their isoelectric point (IP)
In what case does a protein act as a emulsifier?
if the surface of a protein are both hydrophobic and hydrophilic side chains
What is a common use of enzymes in the food industry?
meat tenderization
What are enzymes responsible for?
in all living cells, all chemical reactions are catalyzed by enzymes
Do proteins impact the color of food?
Some proteins can affect the color of food
why are eggs added to cakes?
The highest foaming protein is in eggs, adding eggs to cake makes a spongy product
How do proteins affect the texture of foods?
They are important for the fibrous texture of meat
What are gliadins and glutenins?
Wheat proteins
What do gliadins and gluteins form together?
Gluten, the strengths of gluten determines the loaf volume of wheat bread
What percentage of fat are considered lean meat?
meat that contains less than 10% fat
What percentage of fat are considered extra lean meat?
meat that contains less than 5% fat
Can starch be a sweeter?
Native starch is tasteless, however hydrolyzed starch is sweet
