NST 11 FINAL SP18 EXAM QUESTIONS
WITH COMPLETE ANSWERS
oxidation - ANSWER-involves highly reactive free radicals and changes the property
of food that usually leads to the breakdown of food
2 main causes of oxidation - ANSWER-exposure to oxygen and exposure to sunlight
_____ are especially vulnerable to oxidation - ANSWER-unsaturated fats
common antioxidant food additives - ANSWER-natural:
vitamin C (ascorbic acid)
vitamin E (tocopherol)
synthetic:
butylated hydroxytoulene (BHT)
butylated hydroxyanisole (BHA)
tertiary butylhydroquinone (TBHQ)
BHA - ANSWER-- free radical scavenger
- high doses: carcinogenic effect in rats and hamsters but NOT mice
- health study: no link between BHA and cancer
BHT - ANSWER-- free radical scavenger
- banned for food use in Japan, Romania, Australia
- in US, classified as GRAS (1979): allowed for use as food additive in small
amounts but barred from infant foods
- high doses: liver and lung tumors (160 pound adult taking 73 grams
per day. )
- ironically marketed as health food supplement in capsule form
- might damage viruses
- has been reported to cure some cancers, but worsen others
-more lipophilic and more absorbed than BHA
nitrates/nitrites - ANSWER-- some foods contain nitrate, which can be converted to
(active) nitrite in the body
- sausage: oldest convenience food (Sumerians 3000BC)
,- NaCl (sodium) alone does NOT inhibit bacterial growth in anaerobic (no oxygen)
conditions
- nitrites/nitrates necessary to make meat safe
- nitrite used as antimicrobial, cured flavor, preserves red color
toxicity of nitrites: nitrites can form _____, which are metabolically activated to
carcinogens - ANSWER-nitrosamines
nitrosamines in preserved food cause _____ - ANSWER-cancer
artificial sweeteners - ANSWER-1. saccharin ; bladder carcinogen; 500x sucrose
2. cyclamate ; Banned in US, not carcinogenic; 50x sucrose
3. aspartame ; 200x sucrose
4. sucralose ; 600x sucrose
5. acesulfane; 200x
6. alitam ; 2000x
aspartame - ANSWER-- main functional group: phenylalanine
- phenylalanine unsafe for people with phenylketonuria (no PAH enzyme)
- without PAH, phenylalanine cannot be metabolized -> high plasma phenylalanine
concentration increase phenylalanine entry into brain -> restrict entry of other
(neutral) amino acids -> affects brain development and function
- 40% of aspartame broken down into aspartic acid, an excitotoxin
- 10% aspartame broken down into methanol in small intestine -> most of methanol
absorbed and converted into formaldehyde (carcinogen)
- no significant link between aspartame and brain cancer
sucralose - ANSWER-- artificial sweetener: in Splenda (which is made up of
sucralose, dextrose, and maltodexrin)
- stable under heat and over broad range of pH levels (unlike aspartame)
- can be used in baking
- can be used in products that require longer shelf life
- ADI: 1500 mg/kg/day
- most ingested sucralose not absorbed by GI system(only 11-27%)
- high dose (360x ADI) -> leukemia
- affects healthy gut microbiota
, - may reduce food intake
Tetrodotoxin - ANSWER--occurs in newts (salamanders) and in about 40 species of
puffer fish.
-Puffers are found in all the warm seas of the world
-It's toxicity has been known for thousands of years and was reported in early Egypt
and China 2-3000 B.C.
-found in the ovaries, the roe and the liver—NOT in the meat, which is a delicacy in
Japan.
Tetrodotoxin contamination is seasonal - ANSWER--Tetrodotoxin in ovaries, eggs,
and liver is highest during the spawning season March-June.
-Puffers are eaten only during October-March.
-The best flavor is during Dec and Jan.
-Used in Haiti in near lethal doses to induce the zombi state.
Tetrodotoxin Toxicity, symptoms, mechanism - ANSWER-Symptoms can occur
within 10 minutes—numbness, tingling of the lips,
tongue and inside of mouth.
-After experiencing general weakness, one is paralyzed in the limbs and chest
muscles
-blood pressure drops and the pulse becomes rapid and weak
-death can occur within 30 minutes.
-LD50 of tetrodotoxin is 8 ug/kg body weight
-Mechanism: BLOCKS the voltage-gated Na+ channel
Saxitoxin - ANSWER-- can be present in shellfish in cooler latitudes (west/east coast
England, northern California to Alaska)
-Occasionally in local areas at greater than 30C north or south latitude, where
shellfish have been consumed for generations, they suddenly become poisonous
and then after 1-3 weeks, they become safe—associated with Red Tides
-produced by the plankton such as Alexandrium catenella in mussels, oysters,
cockles, scallops, and clams. The plankton are broken down or simply excreted in 1-
3 weeks
Saxitoxin effect - ANSWER--paralyzing nerve toxin
Domoic acid - ANSWER--kainic acid analog neurotoxin that causes amnesic
shellfish poisoning (ASP). It is produced by algae and accumulates in shellfish, and
small fishes.
Domoic acid mechanism - ANSWER--DA is an agonist of glutamate receptor
(AMPA/KA receptor) that can cause over-excitation of neurons
-Overstimulation of glutamate receptor causes neurodegenerative diseases and
neuronal damage.
Ergotism - ANSWER--long term ergot poisoning
- Ergot—from Claviceps purpurea—fungus grows in individual rye kernels or other
cereals.
WITH COMPLETE ANSWERS
oxidation - ANSWER-involves highly reactive free radicals and changes the property
of food that usually leads to the breakdown of food
2 main causes of oxidation - ANSWER-exposure to oxygen and exposure to sunlight
_____ are especially vulnerable to oxidation - ANSWER-unsaturated fats
common antioxidant food additives - ANSWER-natural:
vitamin C (ascorbic acid)
vitamin E (tocopherol)
synthetic:
butylated hydroxytoulene (BHT)
butylated hydroxyanisole (BHA)
tertiary butylhydroquinone (TBHQ)
BHA - ANSWER-- free radical scavenger
- high doses: carcinogenic effect in rats and hamsters but NOT mice
- health study: no link between BHA and cancer
BHT - ANSWER-- free radical scavenger
- banned for food use in Japan, Romania, Australia
- in US, classified as GRAS (1979): allowed for use as food additive in small
amounts but barred from infant foods
- high doses: liver and lung tumors (160 pound adult taking 73 grams
per day. )
- ironically marketed as health food supplement in capsule form
- might damage viruses
- has been reported to cure some cancers, but worsen others
-more lipophilic and more absorbed than BHA
nitrates/nitrites - ANSWER-- some foods contain nitrate, which can be converted to
(active) nitrite in the body
- sausage: oldest convenience food (Sumerians 3000BC)
,- NaCl (sodium) alone does NOT inhibit bacterial growth in anaerobic (no oxygen)
conditions
- nitrites/nitrates necessary to make meat safe
- nitrite used as antimicrobial, cured flavor, preserves red color
toxicity of nitrites: nitrites can form _____, which are metabolically activated to
carcinogens - ANSWER-nitrosamines
nitrosamines in preserved food cause _____ - ANSWER-cancer
artificial sweeteners - ANSWER-1. saccharin ; bladder carcinogen; 500x sucrose
2. cyclamate ; Banned in US, not carcinogenic; 50x sucrose
3. aspartame ; 200x sucrose
4. sucralose ; 600x sucrose
5. acesulfane; 200x
6. alitam ; 2000x
aspartame - ANSWER-- main functional group: phenylalanine
- phenylalanine unsafe for people with phenylketonuria (no PAH enzyme)
- without PAH, phenylalanine cannot be metabolized -> high plasma phenylalanine
concentration increase phenylalanine entry into brain -> restrict entry of other
(neutral) amino acids -> affects brain development and function
- 40% of aspartame broken down into aspartic acid, an excitotoxin
- 10% aspartame broken down into methanol in small intestine -> most of methanol
absorbed and converted into formaldehyde (carcinogen)
- no significant link between aspartame and brain cancer
sucralose - ANSWER-- artificial sweetener: in Splenda (which is made up of
sucralose, dextrose, and maltodexrin)
- stable under heat and over broad range of pH levels (unlike aspartame)
- can be used in baking
- can be used in products that require longer shelf life
- ADI: 1500 mg/kg/day
- most ingested sucralose not absorbed by GI system(only 11-27%)
- high dose (360x ADI) -> leukemia
- affects healthy gut microbiota
, - may reduce food intake
Tetrodotoxin - ANSWER--occurs in newts (salamanders) and in about 40 species of
puffer fish.
-Puffers are found in all the warm seas of the world
-It's toxicity has been known for thousands of years and was reported in early Egypt
and China 2-3000 B.C.
-found in the ovaries, the roe and the liver—NOT in the meat, which is a delicacy in
Japan.
Tetrodotoxin contamination is seasonal - ANSWER--Tetrodotoxin in ovaries, eggs,
and liver is highest during the spawning season March-June.
-Puffers are eaten only during October-March.
-The best flavor is during Dec and Jan.
-Used in Haiti in near lethal doses to induce the zombi state.
Tetrodotoxin Toxicity, symptoms, mechanism - ANSWER-Symptoms can occur
within 10 minutes—numbness, tingling of the lips,
tongue and inside of mouth.
-After experiencing general weakness, one is paralyzed in the limbs and chest
muscles
-blood pressure drops and the pulse becomes rapid and weak
-death can occur within 30 minutes.
-LD50 of tetrodotoxin is 8 ug/kg body weight
-Mechanism: BLOCKS the voltage-gated Na+ channel
Saxitoxin - ANSWER-- can be present in shellfish in cooler latitudes (west/east coast
England, northern California to Alaska)
-Occasionally in local areas at greater than 30C north or south latitude, where
shellfish have been consumed for generations, they suddenly become poisonous
and then after 1-3 weeks, they become safe—associated with Red Tides
-produced by the plankton such as Alexandrium catenella in mussels, oysters,
cockles, scallops, and clams. The plankton are broken down or simply excreted in 1-
3 weeks
Saxitoxin effect - ANSWER--paralyzing nerve toxin
Domoic acid - ANSWER--kainic acid analog neurotoxin that causes amnesic
shellfish poisoning (ASP). It is produced by algae and accumulates in shellfish, and
small fishes.
Domoic acid mechanism - ANSWER--DA is an agonist of glutamate receptor
(AMPA/KA receptor) that can cause over-excitation of neurons
-Overstimulation of glutamate receptor causes neurodegenerative diseases and
neuronal damage.
Ergotism - ANSWER--long term ergot poisoning
- Ergot—from Claviceps purpurea—fungus grows in individual rye kernels or other
cereals.
