lecture 8-saftey and adverse effects

Question 1

what makes a substance toxic?

Answer 1

if it is consumed in a quanity/[]/under conditions that have or may have immediate or long term harmful effects to the body

Question 2

what is LD50

Answer 2

it is the dose that will kill 50% of animals in the test series

Question 3

what are the three levels of toxicity?

Answer 3

1. acute toxicity: eat something→ symtpoms within 1 hour to day
2. subacuate toxicity: symptoms develop within 2-4 weeks after consumption
3. chronic toxicity: this results in long term health consequences

Question 4

what is ADI

Answer 4

the acceptable daily intake, is the maximum level of daily intake of a toxic substance.

Question 5

define natural toxins

Answer 5

these are toxins that are produced by living organisms that are not harmful to themselves. but other toxic to others when eaten. The chemicals have a diverse function, structure and level of toxicity.

Question 6

gram positive and gram negative bacteria produce different toxins, what are they?

Answer 6

gram positive: produce exotoxins which are mainly protiens. They are heat stable

gram negative: produces endotoxins which include protiens and other components in their structre. They are bound to cell wall and are released upon disrubtion

Question 7

give an example of a gram negative and positive bacteria which produces toxins

Answer 7

1. positive: clostridium botulinum (neurotoxin)
2. negative: e. coli

Question 8

what are methods to prevent bacterial intoxication?

Answer 8

1. thermal treatments: inactive cells, and spores, denature toxins (remember exotoxins are resistant)
2. adicification
3. low water activity
4. antimicrobial additives

Question 9

plant toxins a form of natural toxins are called?

Answer 9

secondary metabolites which are compounds made by organisms that are not essential to their growth or reproduction

Question 10

what are endogenous toxins?

Answer 10

toxic substances which are naturally present in a food item

Question 11

what are lectins?

Answer 11

They are a substance contained in many pulses, it only takes a few raw beans to cause serve gastrointestinal issues. They bind to red blood cells. Not to fear tho lectins can be destroyed when soaked and boiled

Question 12

what are protease inhibitors

Answer 12

Released by plants in response to damage or infection. They block active site of protease and form a very stable complex which results in reduced protien digestion rate and reduces the quality of protien

Question 13

describe kuntiz soybean trypsin inhibitor

Answer 13

KTI forms a highly stable non covalent complex with active site of trypsin making the enzyme inactive. The binding that happens is irreversible

Question 14

Describe bowman brik soybean proteinase inhibitor

Answer 14

Binding sites for both trypsin and chymotrypsin forming tight binds, it is reversable though, so it basically delays digestion. The big problemw with this inhibitor is that is is very heat, and acid and base stable

Question 15

what are the physical processes to inactivate inhibtors

Answer 15

1. thermal
2. extrusion
3. ultrasound: sound waves with a high frequency cause unstable blubbles in liquid which disrupt peptide structure
4. ultra filtration: removes small molecular weight peptides
5. soaking: increase moisture→ smaller molecular weight and more water soluble

Question 16

what are the chemical processes to inactivate inhibitors

Answer 16

1. reducing agents: break dislfide bonds and stable 3 structure
2. acids and bases: destabilize intramolecular electrostatic bonds and stabilize 3 structure

Question 17

what are the biological processes to inactive inhibitors

Answer 17

1. germination: through germination the enzymes in the seeds come out and hydrolyze protiens
2. fermentation

Question 18

what is avidin?

Answer 18

a glycoprotien present in egg which binds biotin

Question 19

what is a food allergy and how is it caused?

Answer 19

an unsual immune response to food protiens. This happens because immunoglobulin E binds to specific amino acid sequence in protien (epitopes)

Question 20

what are the two types of epitopes?

Answer 20

1. continous (sequential-from sequence)
2. discontinous (conformational-from structure)

Question 21

in simple words what is the development process of allergic reactions?

Answer 21

1. sensitization: allergen is recognixed by cells like dendrtitic cells which activates T-cells -> which stimulates B cells and they will differantiate and produce IgE antibodies these will bind to receptors on mass cells and basophils and now they are primed and ready to react at subsequent exposures
2. re-exposure: at a later exposure the allergan will bind to the antibodies on the mast cell, which will cross link and activate the mast cells which will release inflamtory things like histamine, from here a cascade of reactions will result in the allergic symptoms

Question 22

what are the identification tests for allergens?

Answer 22

1. skin prick tests or oral food challangen: this is where the patient is exposed to the known allergen epitopes and observe if they have a reaction
2. ELISA assay: uses antibodies to bind the allergen in a sample, followed by an enzyme-linked reaction that produces a measurable color change. The intensity of the color indicates the allergen concentration. Normally done in for food but can be done in people, by taking a blood sample and seeing if it binds.

Question 23

whats the difference between contains and may containg warnings?

Answer 23

1. contains: list of common allergans known in the product
2. may contain: is a list of allergans which may have enterted the product

Question 24

which method can get rid of allergens

Answer 24

None literally none, the only real solution is to complete exlude it

Question 25

what are methods that can reduce allergencity

Answer 25

1. thermal treatment 2. ultrasound 3. high pressure treatments 4. gamm irradation the principle behind all these methods is that it induces structural changes in protiens which disrupts or destroys the IgE epitopes

Question 26

what is the difference between celiac disease and gluten sensitivity (intolerance) and gluten allergy

Answer 26

Celiac disease is an autoimmune disease not an allergy, the body is trying to fight against gluten like its a virus. Celiac disease is a result of an abnormal gene. Gluten intolerance is when people experience symtpoms after having gluten but have no marker of autoimmune marker of celiac disease or IgE mediated reaction of a food allergy. And gluten allergy is IgE mediated and results in the overreaction of the immune system after you eat gluten.

Question 27

explain what is believed to cause gluten intolerance?

Answer 27

not exactly known but some research says its not gluten itself but certain carbs in food that arent absorbed and stay in the gut and ferments causing sickness

Question 28

what is the challange in producing gluten free products especially related to oats

Answer 28

Oats are 100% contaminated from wheat and therefore still pose a risk, they must recieve documentation and be tested for segreation. Gluten has a large air holding capacity so it must be done with something else like guar gum or xanthan gum. Pulse flours are frequently used as a sub

Question 29

what are gluten sources

Answer 29

1. wheat 2. barley 3. rye 4. triicale 5. oats (no gluten but contaiminated)

Question 30

explain the formation of the processing induced toxin: acrylamide

Answer 30

Acrylamide is formed during the malliard reaction. It happens because of a reaction between asparagine and reducing sugars in starchy foods. It is carcinogenic, but there is no universally agreed safe level in food

Question 31

what are other malliard reaction products that are bad

Answer 31

1. carboxymethyl lysine (CML) 2. heterocylcic amines (HCA) 3. Advanced glycation end products (AGE): carsinogenic and with adverse affects

Question 32

what are indicators used to monitor malliard reactions progression

Answer 32

1. Hydroxymethylfurfural (HMF) : indicator of reaction progession 2. furosine: indicator of heat damage

Question 33

explain the formation of the processing induced toxin: nitrosamines

Answer 33

nitrate is reduced into nitrite, which can be absorbed into blood stream where it will react with myoglobin and make nitroasamine. This occurs in high heat and acic enviroments. they are commonly folund in cured meats and are carcinogenic.

Question 34

why are nitrates and nitrite added to cured meats?

Answer 34

for color, flavor and preservation. The perservation is especially important to work agaisnt C. botulinum which is aneorbic this is especially important for vaccum packaged meats as that is the best condition for that bacteria.

Question 35

what are the strategies to decrease nitroasamine fromation

Answer 35

1. temperature control: avoiding high heat 2. incorporating inhibitors: prevent reduction 3. limiting nitrites and nitrates: have a balance between beneifts and negatives