Lesson 12 & 13 Flashcards
toxicants in food and foodborne disease; functional foods and natural health products
Is it possible for foods to be completely safe?
i.e. zero risk of harm, free of harmful chemicals
- all foods consists consist of chemicals
- all substances (chemicals) are toxic at some level and potentially harmful
- zero risk is unattainable in food safety (and in life)!
Toxicant
from Latin “toxicum” (poison)
substance that can produce a whole spectrum of effects (minor to death)
Toxicity
ability of a chemical to damage a biological system
* substances vary in toxicity and individuals vary in sensitivity
* measures short-term poisoning (acute toxicity) by LD50 (mg/kg b.w. or ppm)
the lower the LD, the stronger the toxicity! any substance with LD50= 50 ppm/kg or lower is considered poison
Hazard
probability that injury will result from the use of a chemical at a given exposure
2 criteria in assessing a hazard
- toxicity or inherent capacity to cause harm
- probability of contact between substance and target object
Strychnine
plant from SE Asia
hazard example
- extremely toxic chemical with LD50= 1.2 mg/kg (small amount causes a severe effect)
- no hazard when sealed in an un-openable vial, preventing contact and allowing it to be freely handled with no chance of poisoning
BUT its toxicity remains unchanged
Boric acid (borax)
hazard example
- mild acid used as an antiseptic, insecticide, flame retardant
- or additive in some cultures (e.g. firming agent, preservative, tenderizer)
not highly toxic (LD50= 1240 mg/kg) but very hazardous when used in a manner that makes it easily available for accidental ingestion
Dose-response curve in terms of toxicity vs hazard
every substance is toxic at some dose but not every substance is hazardous at commonly used doses
Constituents
naturally occuring toxicant
part of the normal composition of food
Contaminants
naturally occurring toxicant
- not originally part of food
- due to bacterial or mould growth on plants and animals within an environment that allow them to become part of food
may lead to foodborne and waterborne diseases
Environmental toxicants
- not originally part of food
- introduced in the environment as a result of human activities
Solanine
naturally occurring constituent
- cholinesterase inhibitor, which inhibits the enzyme cholinesterase through nerve transmission/impulses
- can cause neurological and GI disorders
Solanine in potatoes
naturally occurring constituent
- present in low levels (e.g. 2-13 mg/100g fresh weight in potato skin)
- increases with sunlight exposure, as signalled by green color (80-100 mg/100g f.w.)
Toxicity and hazard of solanine in potatoes
and symptoms
- toxic (LD50= 42 mg/kg) but relatively low hazard/risk (unless green)
- experience drowsiness, difficult breathing, increased sensory sensitivity at 2-8 mg/kg b.w.
How can you reduce solanine levels in potatoes?
- insoluble in water but can reduce concentration by peeling
- not destroyed by heat/cooking
Cyanogenic glycosides
naturally occurring constituents
compounds that yield HCN (hydrogen cyanide) upon enzymatic action (beta-glucocidase) or acidic conditions
e.g. amygdalin in bitter almonds and fruit pits, linmarin in cassava, lima beans
Toxicity and hazard of cyanogenic glycosides
- toxic (LD50= 0.81 mg/kg) but low hazard from accidental consumption of fruit seeds
- fatal in humans at 0.5-3.5 mg/kg (e.g 100g bitter almonds or dried bitter cassava root) but non-fatal at lower doses
increase in hazard if bitter almonds, cassava, lima beans, etc. are part of staple diet
2 most common mycotoxins
naturally ocurring contaminant
produced by moulds
* Ergotism alkaloid (St. Anthony’s Fire) produced by Claviceps purpurea
* Aflatoxins produced by Aspergillus flavus
Ergotism alkaloid (Claviceps purpurea)
mycotoxin
a grain of ryegrass infected with ergot (Claviceps purpurea)
* vaso-constricting (constricts blood flow to brain) and precursor for LSD 25, causing hallucinations
linked to salem witch hunt “hysteria”
Aflatoxins (Aspergillus flavus)
highly toxic and potently carcinogenic (liver cancer)
found in peanuts, corn, wheat, rice, cottonseed, nuts, milk, eggs, cheese
Examples of seafood toxins
naturally occurring contaminants
- Histamine
- Saxitoxin
- Domoic acid
- Tetrodoxin
Histamine
seafood toxins
from histidine, a naturally occurring amino acid, produced in high levels by bacteria action on fish flesh (e.g. scombroid fish like tuna, bonito, mackerel, skipjack)
bacteria converts histidine > histamine
Symptoms of scromboid poisoning
histamine in scombroid fish
eating scombroid fish = nausea, vomiting, facial flushing, thirst, skin itchiness
must ensure it’s completely cooked or from a reputable source
effects subside ~12 hrs
Saxitoxin
seafood toxin
- produced by dinoflagellates, found in plankton responsible for red tides
- prevalent in shellfish (e.g. mussels, clams, oysters), which are “filtering organisms” that absorb saxitoxin and concentrate it in their tissues
Red tide
i.e. bloom
source of saxitoxin
* when microscopic plankton (containing dinoflagellates) bloom, forming a red tide
Paralytic shellfish poisoning (PSP)
saxitoxin in shellfish
- lethal at a certain dose (toxic) but hazard depends on your love for shellfish and its source (when/where its harvested)
- can cause muscular and nerve paralysis
e.g. ignoring red tide warning signs
Amnesic shellfish poisoning
domoic acid in blue mussels
domoic acid, a neurotoxin produced by plankton, can cause lesions in the CNS, resulting in permanent memory loss
hazard depends on consumption of shellfish (e.g. ignoring signs indicating closure of areas to shellfish harvesting)
Fugu poisoning
tetrodotoxin in puffer fish
- produced by a bacteria associated with the ovaries, liver, intestine, skin of puffer fish
- toxic at low dose and hazard depends on passion for puffer fish, its proper cleaning and gutting
its meat is considered a delicacy!
5 kinds of environmental toxicants
- food packaging residues (e.g. monomers of plastic resins)
- pesticide (e.g. herbicides, insecticides, fungicides) residues (e.g. malathion on fruit)
- heavy metals (e.g. lead, mercury, cadmium)
- animal drugs (e.g. antibiotics, hormones, penicillin in milk)
- radioisotopes (e.g. from soil or radioactive fallout)
Symptoms of fugu poisoning
tetratodoxin in puffer fish
- tingling sensations (fingers, toes, lips, tongue) minutes after eating
- reflexes of pupil and cornea are lost
- paralysis, respiratory distress, death
3 kinds of processing-induced toxicants
- acrylamide (heated starch)
- benzene (irradiated food)
- ACBs (irradiated food)
acrylamide can be produced from maillard reaction
Main causes of foodborne illnesses
general public vs regulatory agency
- food additives according to general public
- microorganisms according to regulatory agency
MOs like salmonella, shigella, e. coli, vibrio, cyclospora, hepatitis A, listeria
Incident
simple occurrence of foodborne illness
an isolated case
Outbreak
foodborne illness in 2 or more people after ingestion of the same food with epidemiological evidence
outbreak of unknown etiology has no epidemiological evidence
3 reasons why foodborne diseases are emerging
- globalization of food supply (pathogens introduced to new areas)
- travel
- change in lifestyle
3 reasons why only some FBD outbreaks are documented
- lack of reporting (only 1-4% reported)
- mistaken diagnosis (e.g. mild cases of FBD wrongly attributed to 24hr flu, virus, eating too much)
- physicians fail to report the case to local health units (not enough evidence/research available)
Who is at highest risk of FBD?
- very old
- very young
- those with weakened immune systems
- expectant (pregnant) mothers
Food intoxication
kind of FBD
due to toxins/toxicants, produced in foods as by-products of MOs, plants plants, or animals, which cause disease upon ingestion
Food infection
kind of FBD
- due to multiplication of pathogenic MOs
- viable MOs in the food at the time of consumption cause growth in the host, which leads to illness
Which foods is Clostridium botulinum commonly in?
food intoxication
low acid foods and anaerobic conditions, potatoes, carrots
found in soil, where carrots and potatoes can harbor C. botulinum
Symptoms of Clostridium botulinum
double vision, dry mouth, paralysis
a neurotoxin!
LD for humans= 1 ng/kg b.w.
Prevention of Clostridium botulinum
- its spores are heat resistant and must undergo botulinum cook (12D process)
- Keep pasteurized (refrigerated)
pasteurization not enough to destroy!
What foods is Escherichia coli 0157:H7 commonly in?
food intoxication
undercooked ground beef, unpasteurized milk and fruit juice, alfalfa sprouts, spinach, drinking water
acid-tolerant (often survive in acidic foods like apple juice)
Symtoms of Escherichia coli 0157:H7
bloody diarrhea > kidney failure (if not treated), hemolytic uremic syndrome (especially in children)
used to be “hamburger disease”
Prevention of Escherichia coli 0157:H7
not spore-forming so easily inactivated by heat (pasteurization) and irradiation
* ensure ground beef is cooked well
* refrigerate (doesn’t grow well at temperatures < 8-10C)
* sanitary food handling
Meat glue
- an enzyme called transglutaminase used to bind small meat scraps into a whole new piece
- produced by cultivating bacteria from the blood plasma of pigs and cattle (coagulant that causes blood to clot)
- used in powdered form in the food industry and can be dangerous to inhale
a permitted food additive (e.g. in meat products, bread, white flour) but poses risk of poisoning, especially when cooked rare
Mechanical tenderization
why is it hazardous?
a process used to soften meat texture by running through a machine that punctures it with blades or needles
- bacteria, deadly pathogens can be pushed deep inside, making them difficult to kill if meat is not cooked thoroughly
- not labelled and cannot be visually identified
What foods is Staphylococcus aureus common in?
food intoxication
contaminated and undercooked food exposed to open wounds and nasal fluid
produce heat-resistant enterotoxin
Symptoms of Staphylococcus aureus
rapid onset of nausea, vomiting, abdominal pain, cramps, and diarrhea
20 ng can cause illness (very potent)
Prevention of Staphylococcus aureus
easily inactivated by heat (pasteurization)
* must cook food well
* refrigerate (doesn’t grow well < 4C)
* sanitary food handling
Which foods is Salmonella common in?
food infection
raw or undercooked poultry, eggs, hogs, ground beef, milk, dairy products
Symptoms of Salmonella
cramps, chills, vomiting, diarrhea, fever
symptoms typically start within 6-72 hrs after exposure and most end within 4-7 days
Prevention of Salmonella
- killed by heat (cooking, pasteurization) and irradiation
- ensure sanitary food handling
Which foods is Listeria common in?
food infection
refrigerated smoked fish, raw or unpasteurized milk, soft and unpasteurized cheeses, ready-to-eat meats
can grow at refrigerated temp!
Symptoms of Listeria
fever, nausea, cramps, diarrhea, vomiting, miscarriage and stillbirth (in pregnant women)
symptoms of severe listeriosis may appear up to 70 days after exposure
Prevention of Listeria
- killed by heat (cooking, pasteurization) and irradiation
- ensure sanitary food handling
control measures in place in ready-to-eat foods
Viruses
do not multiply in food, instead usually oral-fecal route of contamination that infects upon ingestion (e.g. shellfish from contaminated water)
e.g. hepatitis A, norovirus (prev. norwalk-like viruses)
Prevention of viruses
- inactivated by thermal processing
- hygiene (sanitary food handling)
Which foods is Norovirus commonly in?
raw shellfish, any food prepared or touched by an infected person
easily spread from the infected person up to at least 3 days after recovery
Symptoms of norovirus
diarrhea, vomiting (usually more in children), nausea, stomach cramps, low-grade fever, headache, chills, muscle aches, fatigue
gastroenteritis within 24-48 hrs but symptoms can start as early as 12 hrs after exposure (illness often begins suddenly)
5 factors in FBD
- inadequate cooling of foods
- preparation of food several hours in advance
- poor personal hygiene and cross-contamination
- insufficient cooking or reheating of food
- improper hot storage
most pathogenic MOs don’t alter the color, aroma, flavor, texture of food (unlike spoilage) so no visual cues to rely on
Top 4 places where food can be mishandled and lead to FBD
- food service establishments
- food processing establishments
- retail food establishments
- homes
4 safe food handling practices
preparing, cooking, serving, storage
- clean hands, utensils, cooking surfaces with soap and hot water, or sanitize with a mild bleach solution
- separate raw and cooked food to avoid cross-contamination
- cook thoroughly, prepare quickly, serve immediately
- chill, refrigerate (< 4C) or freeze (-18C) within 2 hrs
avoid temperature danger zone (TDZ) between 4-60C
Hazard analysis and critical control points (HACCP) system
processing flow diagram designed to anticipate and control problems before they happen
7 HACCP steps
- identify hazard (FATTOM)
- determine CCP
- institute control measures
- monitor CCP
- take corrrective action
- keep records
- verify procedures
FATTOM= food, acidity, time, temperature, oxygen, moisture
most crucial step is preservation (e.g. receiving > clarification > homogenization > pasteurization > packaging)
3 conditions of FOSHU (Japan)
leading country in functional foods
- derived from naturally occurring ingredient
- consumed as part of the daily diet
- has health-enhancing function
Natural health products
prev. nutraceuticals
- isolated or purified from foods
- sold in medicinal forms not usually associated with foods
- have proven physiological benefits
require a natural product number (NPN) or homeopathic medicine number (DIN-HM)
Funtional food
a food consumed as part of the daily diet and is demonstrated to have physiological benefits and/or reduces risk of chronic disease beyond basic nutritional functions
e.g. omega-3 eggs
fortified with 3 essential antioxidants (vitamin C, E, selenium) to promote a healthy immune system, protect cells and tissues
4 classifications of functional foods
according to source
- traditional raw (non-processed) foods (e.g. oat bran, flax seed, garlic, fish with omega-3s)
- processed food w/ no added ingredients (e.g. high fiber cereal, soy products, flaxseed oil)
- processed foods with added ingredients (e.g. Ca-fortified OJ, omega-3s in yogurt)
- genetically-engineered foods (e.g. tomatoes with lycopene)
Claim about soy
soy protein decreases cholesterol and are anticarcinogens
Claim about flaxseed
has high amount of omega-3 FAs and lignan, which reduces cholesterol (substantiated) and breast cancer (not)
Claim about tomatoes
lycopene in tomatoes is an anticarcinogen
Claim about garlic
alicin and sulfur containing compound = antibiotic, anticarcinogen, antihypertensive (lower cholesterol)
Claim about beef and whole milk
conjugated linoleic acid (CLA) is an anticarcinogenic and facilitates weight reduction
Probiotics
- products containing health-promoting microorganisms (improve intestinal microflora balance)
- high # viable organisms required for benefits: reduced risk of colon cancer and GI disorders, stimulate immune system
e.g. Lactobacillus and Bifidobacterium in yogurt, fermented milk (also available as natural health products)
Novel food
Health Canada
a substance, including a MO, that doesn’t have a history of safe use as a food yet
