topic 7

Question 1

what is the difference between unintentional toxins and naturally occurring toxins?

Answer 1

unintentional toxins: accidental, they are not there naturally and often occur due to external processes (eg. improper use of pesticides; eg. coal burning causes accumulation of mercury in tuna which can be an issue for pregnant women).

naturally occurring toxins: occur naturally in foods, not due to any external processes (eg. coniine in hemlock, green potatoes that have solanine, poisonous mushrooms, mould, etc.)

Question 2

How do unintentional toxins enter the food supply?

Answer 2

Due to human error/action. Aldicarb (pesticide) entered food due to improper use and mercury enters food web due to coal burning which goes into air, then reacts with bacteria in water which in turn turns into methyl mercury in fish (so higher trophic levels = + mercury).

Question 3

How do naturally occurring toxins enter the food supply?

Answer 3

They are present there naturally so they don’t really enter per se. In some cases, they can arise from time (mould) or breakdown of proteins (histamine)

Question 4

difference between celiac, silent celiac, latent celiac, non-celiac gluten sensitivity

Answer 4

celiac: diagnosis by positive endoscopy, positive anti-tissue transglutaminase test (ANTI-tTG)

silent celiac: no symptoms, but positive blood test and biopsy

latent celiac: positive blood tests, but normal endoscopy, watchful waiting without a gf diet

non-celiac gluten sensitivity: no positive blood test or biopsy, diet helps with certain symptoms

Question 5

Classical food allergy leads to…

Answer 5

swelling, nausea, cramping, diarrhea, eczema, itching, vomiting, flatulence, asthma, rhinitis, anaphylaxis (collapse in circulatory system that can lead to death)

Question 6

How do allergic reactions work?

Answer 6

Body’s immune system attacks foreign substance that presents no danger by generating antibodies (protein). The latter engulf the allergen which manifests an allergic reaction. 1st exposure leads to antibody formation, 2nd exposure leads allergen exposure reaction.

Question 7

What can reverse an allergic reaction? Why do we need to go to the hospital anyways?

Answer 7

Epinephrine/adrenaline can reverse the allergic reaction, but epi-pen needs to be in reach. It just buys time, but reaction can reoccur, so must be monitored.

Question 8

what is hypoglycemia and how is it treated?

Answer 8

low blood sugar, the solution is to have small meals rather than high carbohydrates meals.

Question 9

T or F: hyperactivity is caused by sugar

Answer 9

False! not caused by sugar, but rather the situation (bday parties, playground, etc.). In fact, it has a calming effect. Eg. Sheriff put prisoners on ice cream diet to calm them down as simple carbohydrates actually have a calming effect.

Question 9

Why does sugar cause sleepiness?

Answer 9

Most of the time a.a. absorption into brain, except for tryptophan which goes into muscle tissue. However, when we eat carbohydrates, this leads to insulin release which enhances absorption of competing a.a. into muscle tissue, leading to tryptophane absorption into the brain. Due to tryptophane being a precursor for serotonin, its absorption calms us down and might induce sleep.

Question 10

What should you eat to stay awake?

Answer 10

To stay awake, you need to consume protein, which contains tyrosine. Tyrosine goes through a cascade (tyrosine – dopamine – norepinephrine – epinephrine) to produce epinephrine (adrenaline = fight or flight hormone!!) which will keep you alert. So it is better to eat tuna before an exam than a bunch of sugar.

Question 11

what are Idiosyncratic reactions

Answer 11

Rare reactions whose origin is unknown

Question 12

MSG causes what adverse food reaction?

Answer 12

Chinese restaurant syndrome or Kwok’s disease, it mimics a heart attack and can cause rare, but fatal asthma

Question 13

How do bacteria cause problems

Answer 13

1.Bacterial infection: particular bacterium multiplies in body and overruns in body.

2. Bacterial intoxication: reaction to poisons produced by bacteria.

Question 14

Salmonella

Answer 14

A bacteria often associated with chicken, causes gastroenteritis symptoms.

Question 15

Campylobacter Jejuni

Answer 15

A bacteria, gastroenteritis symptoms, can lead to guillain barre syndrome, similar to MS where protective layer around nerve is worn away, most ppl recover

Question 16

listeria monocytogenes

Answer 16

bacteria founds in high protein foods (cheese and processes meats) that can grow at fridge temperatures. Can come into food due to contaminated equipment (eg.Maple leaf screw in cold cut machine led to infection.)

Question 17

Staphylococci

Answer 17

Bacteria found in skin and nasal secretions (so sneezing is a risk of contamination), produces a toxin that is heat stable (so heating doesn’t get rid of it).

Question 18

Clostridium botulinum

Answer 18

v dangerous bacteria due to it’s toxin (0.0000001g can kill you). Paralysis onset is indicative of poisoning, it is anaerobic so it multiplies when no oxygen is present (so even if sealed it can proliferate).

Found in bottle garlic, but also botox

Question 19

E. Coli O157:H7

Answer 19

Found in animal intestines, makes its way during butchering of animals which causes it to enter meat we later eat. Can be destroyed if cooked properly (70C internal temp). Also affects sprouts

Question 20

Hepatitis A

Answer 20

virus, flu like symptoms, but also diarrhea and jaundice

Question 21

How can cross contamination be prevented

Answer 21

• don’t use same utensils for raw and cooked meats.
• don’t put unwashed vegetables with washed ones;
• cook things properly; keep cold and hot foods the temperature they are supposed to be, do not keep foods between 5-60C for any length of time.
• leave out hot food no more than 2 hours.
• don’t sneeze on food
• wash your hands well with soap for the length of happy birthday (30-35 seconds)

Question 22

Maillard reaction

Answer 22

carbohydrates and proteins combine when they are heated, causes loss of water. Causes browning, probably not harmful.

Question 23

Polycyclic aromatic hydrocarbons (PAH)

Answer 23

due to cooking meats cook –> fats drip, vaporized fat comes back up in altered form and sticks due to dehydration. Can form 2 flat carcinogenic molecules: benzopyrene and anthracene (both have no OH groups), they are also are present in exhaust in engines and tobacco smoke.

Question 24

Heterocyclic amines

Answer 24

flat, interact with DNA by intercalation, slipping into the slot that DNA provides, PhIP.

Question 25

What ingredients do you need to make bread?

Answer 25

Flour, water, yeast, salt

Question 26

What happens when carbs are fed to yeast?

Answer 26

CO2 and ethanol are produced

Question 27

What is sodium bicarbonate and what is it used for in cooking?

Answer 27

Baking soda! it is a leavening agent but can also be used to keep the emerald green color of foods

Question 28

How does baking soda work?

Answer 28

In the presence of acid (eg. HCl like stomach acid), 2H and 1 O from the baking soda combine to form water which leaves CO2. The latter causes the bread to rise.

Question 29

How does baking soda preserve green color?

Answer 29

Porphyrin ring system with Mg ion in middle it makes chlorophyll. When vegetables are heated, acids are given off and the Mg is replaced by 2 protons (H+) which makes protoporphyrin. Protoporphyrin is subtly less green, more like a canned pea colour. Adding sodium bicarbonate (baking soda) to boiling of frozen peas can keep the emerald color. Neutralization of the acids causes frothing (CO2) during boiling. Doesn’t really change the nutritional value, just cosmetic.

Question 30

What is baking powder?

Answer 30

has monocalcium phosphate, an acid, and sodium bicarbonate. So, the two mix to produce CO2. So if you add water to it, it will fizz.

Question 31

How does self raising flour work?

Answer 31

it has an acid (calcium phosphate monobasic) and sodium bicarbonate (AKA baking powder). Same thing in cake mixes.

Question 32

how does ripening work?

Answer 32

anthocyanines (red) takes over/masks the chlorophyll (green). Happens in peppers and tomatoes

Question 33

why do onions cause crying?

Answer 33

because they have a sulfur containing compound with 1 oxygen which decomposes when heating. So if you peel it under water, you are less likely to cry as this compound is water soluble.

Question 34

Protein denaturation, what is it?

Answer 34

Unraveling of protein structure during heating. Water is release and causes egg white to become opaque.

Question 35

Why does the egg yolk require more time to cook than the egg white?

Answer 35

Because it has a higher fat content which causes it to require more heat to solidify

Question 36

What allows to blind the egg?

Answer 36

Covering your egg, with aluminum or a lid, will cause water to be trapped and cook the white on top of the egg yolk.

Question 37

T or F: brown and white eggs are nutritiously different

Answer 37

FALSE, just depends on chicken

Question 38

what happens when you overcook a boiled egg?

Answer 38

It turns green/gray. . Colour is due to FeS (iron sulfide) which is pushed out to the surface when cooking goes on for too long. (Fe2+ + H2S –> FeS)

Question 39

What is lecithin

Answer 39

component of egg yolk, it is an emulsifier, aka allows mixing of oil and water in eg. Mayonnaise. Has one end being charged and other part is a long chain hydrocarbon (looks like oil). Former is polar the latter is non-polar. The water will associate with the polar end and the oil will associate with the non-polar end which creates an emulsion.

Question 40

T or F: concerning meats: “As exterior pores contract, the moisture contained in the object cannot escape”

Answer 40

NOT TRUE and did not originate from Aristotle.

Question 41

T or F: you need to cook meat with less fat and less collagen to soften it.

Answer 41

FALSE, meats with more fat and collagen require + cooking for + softening to occur. That’s why cuts like filet mignon require less cooking time.

Question 42

What is instant meat tenderizer?

Answer 42

contains papain, a natural material that breaks down protein in meat to make it softer.

Question 43

what is transglutaminase (TG)?

Answer 43

meat glue, an enzyme that combines two ends of amino acids on protein chains together. Essentially linking them and giving off ammonia.
Packets are called Activa. Allows to fuse meat back together chemically. Works for fish.

Question 44

How do induction stoves work?

Answer 44

copper wire is placed underneath the cooking - an alternating current flows through the coil creating a magnetic field which, in turn, induces an electric current in the ferromagnetic pot. High current-low voltage. Thinks heated only where ferromagnetic material is present. You can control temperature really well unlike electric stoves.

Question 45

Untensil materials need to be chemically unreactive and conduct heat evenly, so what material obey these requirements?

Answer 45

Silver, copper fry pans (conduct heat well), iron fry pans, stainless steel (sticks a bit unless you use a lot of oil), aluminum (quick cooking), ceramic (cook much longer), Teflon (no sticking), all-clad (stainless steel/copper/aluminum so quite heavy)