Food Toxicology

Question 1

what are contaminants?

Answer 1

• included unintentionally in food (by accident)
• some are harmless, others are hazardous
• occur at every step from raw materials to consumer
  
  • raw material –> processing –> packaging –> storage –> consumption
• 3 types of contaminants
  
  • biological –> bacteria, mold, fungus, parasites, virus
  • chemical –> accidental contamination with chemical; heavy metal, pesticides
  • physical –> accidental contamination with object –> fingernail touch

Question 2

what are additives?

Answer 2

• anything added intentionally to food
• purpose
  
  • maintain/ improve safety and freshness
  • improve or maintain the nutritional value
  • improve taste, texture and appearance
• examples: colorant, stabilizer, emulsifier, etc.

Question 3

what are nitrogenous compounds

nitrates and nitrites

Answer 3

• sodium and potassium nitrite and nitrate –> as food additives in meat, fish, and cheese –> help hinder microbila growthm keep meat red and enhance flavor
• nitrates/ nitrites + amines/ amides/ guanidines/ ureas –> N-nitroso compounds (NOC)
• nitrosamine or nitrosamide –> are carcinogenic

Question 4

what are mycotoxins?

Answer 4

• toxic secondary metabolites
• in cereal grains, coffee, nuts, spices and milk from contaminated animals
• organic food more susceptible to mycotoxin contamination –> organic food no use pesticides (that’s why)

Question 5

what are aflatoxins?

Answer 5

• cause hepatotoxicity and carcinogenicity
• undergo complex hepatic metabolism to form large numbers of metabolites
• aflatoxin B1 is metabolized by CYP 3A5/1A2 into aflatoxin B1-8,9-epoxide
• will undergo DNA adduction and become a mutagenic adduct

Question 6

what are trichothecenes?

Answer 6

• produce by fusarium and myrothericum
• cause intestinal irritation in mammals, vomiting, skin inflammation, diarrhea, multiple hemorrhages
• are protein synthesis inhibitors –> bind to ribosomes (peptidyl transferase)

Question 7

substances that are produced by cooking? (pt.1)

Answer 7

heterocyclic amine:
* the result from high temperature of cooking proteins and carbohydrates
* usually found inn broiled beef, chicken, mutton, and grilled fish

Question 8

substances that are produced by cooking? (pt.2)

Answer 8

acrylamide:
* formed in food that are high in carbs, and is cooked at >120o
* examples:
* toast bread, cakes, fries, potato chips

Question 9

mechanism toxicity of acrylamide

Answer 9

• repeated exposure/ dose of acrylamide –> produce morphological changes in brain areas (learning, memory cognitive function)
• acrylamide exposure –> increase risk of cancer (metabolized in glycidamide DNA damage)

Question 10

what is MSG

Answer 10

• sodium salt of glutamic salt
• can be found in nature and man-made
• enhance natural flavour and palatability in foods

Question 11

how MSG cause toxicity?

Answer 11

• MSG can cause chinese restaurant syndrome
• large dose of MSG IM can degenerate nerve cells in brain
• neonatal MSG consumption –> development of obesity later

Question 12

mehanism toxicity of MSG?

part 1

Answer 12

1. disrupt the stroma cells and basement membrane
2. cause oxidative stress and DNA damage
3. cause cellular hypertrophy of the thecafolliculi in ovaries
4. all will lead to reproductive abnormalities