Chapter 8 Flashcards
Six main causes of “unsafe” food
Presence of disease producing ( pathogenic )
Presence of natural toxins
3.
Presence of extraneous matter (e.g., stones, glass, seeds,
4.
Presence of environmental contaminants (e.g., pesticides, heavy
metals in fish)
5.
Presence of harmful additives
6.
Presence of allergens (puts only certain individuals at
two typesof pathogenic organisms
Microorganisms [includes viruses, bacteria, molds, and protozoa (parasites)]
Parasitic nematodes (e.g., trichina worm ””, occurs in rats, pigs, and humans,
responsible for the disease trichinosis)
Examples of natural toxins
(e.g., poisonous mushrooms, cyanogenic
glucosides in cassava)
Why everybody is so concerned about food safety, especially the ones producing diseases
Globalization of trade Trend toward food distribution over a broad geographic area from centralized production and storage facilities Emergence of new foodborne pathogens
What was the hamburger disease that then transferred to sprouts, lettuce, and spinach
E.g., emergence of the pathogenic strain E. coli O157:H7 in beef (“hamburger
disease”) in the 1980s; subsequent outbreaks were traced to contaminated
sprouts, lettuce, and spinach as well as beef (XL Foods in Alberta in 2012)
What is the rate of food poisoning in US, hospitalization and deaths
: 75 million
cases/year in the USA (up to 30 % of the
325,000 hospitalizations, 5000 deaths
Economic costs of food poisoning
estimates range from 20 billion to $ 45 billion/year:
Categories of losses from food borne diseases
Healthcare costs Costs of public health investigations Lost productivity Loss of market share (company responsible for an outbreak) Loss of consumer confidence (can be far reaching)
What is the leading cause of food loss/waste
In addition to being a major food safety concern, microbiological
contamination is a leading cause of food loss/waste through
spoilage
According to the FDA, mercury level in canned tuna is 0.126 ppm. In this case,
mercury is an example of ……. contaminant in food. (one word, small letters)
Environmental
Microorganisms of concern in food microbiology include
bacteria and
fungi (yeasts and molds
Bacteria and fungi can ___ in food
These microorganisms can proliferate rapidly in foods.
What type of microogranisms do not proliferate in food
Viruses
Within the context of traditional food microbiology, the term
“microorganisms” refers to bacteria and
Bacteria and fungi
The particular bacterial/fungal species responsible for foodborne
illnesses (pathogenic microorganisms) ____ those
causing food spoilage .
are not the same as
When microorganisms can bee beneficial
fermented products: yogurt, cheese, sauerkraut, wine
When milk, meat and vegetables/fruits will be exposed to microbial contamination
Milk from a cow is sterile originally but not for long
Meat can become contaminated in the slaughterhouse or by handling after
slaughter.
Bruising of fruits and vegetables during and after harvesting provides
points of entry for microorganisms.
bacteria reproduce by ___ , resulting in an
____ of growth : population can double every 20 30 min.
binary fission
exponential rate
What is a routine step in food quality control
Microbiological analysis
Microbiological analysis involves
It can involve the detection , enumeration , and/or identification of
microorganisms
What is standard plate count
: method for general enumeration of
microorganisms (total microbial load).
High total microbial loads are the effects of
poor sanitary control in the
production, transport, processing, or storage of the food.
There is a ____ in microbiological standards
Upper limit on total microbial load
Standard for grade A raw milk is
microbial load is not to exceed 100,000 per milliliter.
Why food poisoning is so difficult to define
Identification of microorganisms is generally a very slow and
complicated process
Milk should not be pasteurized before making yogurt or cheese. The
natural bacteria is needed for the fermentation process.
True/false?
False
Bacteria are ___ organisms and can be in the shape of
Bacteria are single cell organisms : they can be spherical, rod shaped, or
spiral
Dimensions of bacteria
1-4 microns
Some bacteria are able to form ___
spores (dormant, largely dehydrated
Spores are extremely resistant to
to adverse conditions (e.g., heat) and can
survive without nutrients, making them extremely difficult to destroy.
Once environmental conditions are favorable,spores can turn into
vegetative cells they once were.
Size of yeasts
20 microns
Shape of yeasts
spherical or ellipsoidal
Yeasts are employed in ___ because
Yeasts are employed in alcoholic fermentation and leavening of dough
(production of CO 2)
Molds are larger and more complex than ___
yeasts
How molds grow
multicellular filaments called hyphae
Are molds bad or good
Molds are very common spoilage organisms but are also employed in
some types of cheese production, e.g., mold ripened cheese.
How microorganisms are able to degrade food systems
Enzymatically
Microbial degradation can result in
textural changes , off flavors
(e. g., putrefaction, rancidity), and production of gases, acids, slimes
(polysaccharides) , or alcohol
Almost all microorganisms grow well in (conditions)
high moisture conditions :
their capability for growth diminishes with a reduction in moisture
levels.
Molds are generally better at growing at lower moisture levels than
bacteria or yeasts.
Mesophilic, thermophilic,psychrophilic and psychrotropic organisms- conditions
Mesophilic organisms grow best over a temperature range of 20
45 C
Thermophilic (heat loving) organisms grow best at temperatures
above 45 C ; some are able to grow at temperatures up to 82 C
Psychrophilic (cold loving) organisms grow best at low temperatures
10 C );
Psychrotrophic organisms are able to grow at refrigerator
temperature ( 4 C
Oxygen requirements for growth of microorganisms and their names
Anaerobes grow in the absence of oxygen
Aerobes grow in the presence of oxygen
Microorganisms can be obligate (require aerobic or anaerobic
conditions) or facultative (can adapt to either
Listeria monocytogenes
can grow in refrigerated foods, hence; it
is considered …… bacteria. (one word, small letters)
PSYCHROTROPHIC
Foodborne illnesses can generally be classified as ___
food infections or
food intoxications
What is food infection
: A pathogenic microorganism establishes itself in the
intestines and causes an infection.
What is food intoxication
A toxin produced by the microorganism causes
illness; the organism itself is not the cause and may even no longer be
present in the food (i.e., it may have been killed
Some microorganisms cause illness by a
combination of the two
mechanisms : i.e., the organism establishes itself in the intestines
and then produces a toxin .
Microorganisms are named according to the
genus and species to
which they belong, e.g., Escherichia coli
How to recognize genus in the name of bacteria
The genus begins with a capital letter , and this letter is used in the
abbreviated form of the name, e.g., E. coli
When additional terms follow the italicized name , they refer to a ___
subspecies or to a serotype ; e.g., E. coli O 157 :H 7 is a serotype.
Sallmonellosis is caused by
: Infection caused by bacteria belonging to the genus
Salmonella : severe gastrointestinal
Sallmonellosis:Estimated number of cases per year in the United States and main vehicle of transmission
1 million
poultry
Listeriosis is a ___
Infection caused by the bacterial species Listeria monocytogenes , often
termed refrigerator disease ” because this species grows in chilled products .
What is the 3 rd leading cause of death
from food poisoning
Listeriosis
Listeriosis has been most often associated with
Listeriosis has been most often associated with raw milk cheeses . However,
ready to eat meats have recently come to the forefront as vehicles for
transmission of L. monocytogenes
What are cold cuts
Ready-to-eat meat products
Campylobacteriosis is ___
: Infection caused by bacteria belonging to the genus
Campylobacter , primarily C. jejuni ; it has become the leading bacterial
foodborne infection worldwide.
Although campylobacteriosis is usually not serious, it can have long term
consequences in some individuals.
Prevention (CDC), ~40% of cases of Guillain Barré syndrome are triggered by
serious condition) are triggered by a bout with campylobacteriosis
C.jejuni- main vehicle of transmission
poultry, raw chicken
The main vehicle of transmission of
Salmonella is
……(one word, small letters)
Chicken
Food intoxications are often characterized by
very rapid onset compared
to food infections (e.g., minutes or hours vs. days or even weeks).
Botulism is caused by
is caused by the bacterial species Clostridium botulinum , which
produces a powerful neurotoxin
Botulism is very rare by usually __
Lethal
Clostridium botulinum is an (conditions and food)
obligate anaerobe and the key organism of
concern in canning of low acid foods
What is the set mark between low-acid and high-acid foods and why
acid foods is pH 4.6 because
spores of C. botulinum are incapable of germinating (i.e., of being
reactivated to the toxin producing vegetative state) at a pH ≤ 4.6
Staphylococcal enterotoxins are
: Toxins produced by bacteria belonging
to the genus Staphylococcus .
Main vehicle of transmission of Staphylococcal enterotoxins
: food contaminated by food handlers (skin)
Once Staphylococcal enterotoxins are produced in a food, they are not
destroyed by subsequent cooking
Enterotoxins only act on the
intestines so this form of food intoxication
is seldom serious.
Mycotoxins are, by definition, toxins produced by
Molds
For example, the mold Aspergillus flavus in moldy
grain/cereals/peanuts produces
aflatoxin (a hepatotoxin).
Acute aflatoxin toxicity resulting in
liver failure and death occurs in
animals but not in humans.
In humans , aflatoxins are potent liver carcinogens : chronic exposure
increases risk of liver cancer.
how many serotypes of e.coli are known
700
What can cause enteric infection and produce
toxins that can cause lysis of red blood cells.
When Shiga toxin producing E. coli (STEC) strains (such as O157:H7)
colonize the intestinal tract
5-10% of people infected with STEC develop
hemolytic
uremic syndrome , which can lead to kidney failure, permanent
kidney damage, or death
infection with E. coli O 157 :H 7 was originally called
Hamburger disease
What food are particularly hazardous to e.coli
Unpasteurized milk and raw milk cheeses as well as raw meat particularly hazardous but no food that is served raw is exempt.
Viruses are not ___but they can be ___
spoilage organisms
pathogenic.
Viruses are ___ than bacteria
Smaller
What are noroviruses
(such as Norwalk virus) are considered to be responsible
for ~50% of all outbreaks of foodborne illness in North America: they
are very easily transmissible through food and water, as well as
from person to person.
Infection with noroviruses is extremely common but seldom a serious
health problem.
What other viruses can be transmitted via food and water
Hepatitis A and polio
The second leading cause of death from foodborne illness (between
salmonellosis and listeriosis) is
toxoplasmosis , a disease associated
with the protozoan parasite Toxoplasma gondii
Describe T.gondii
is a single celled eukaryotic organism that can survive outside
a host in a dormant form ( cysts ) or as eggs (oocysts) for lengthy
periods.
T. gondii can be transmitted as cysts in contaminated food and water
(as well as by other routes) and infects all warm blooded animals,*
including a large proportion of humans.
Who are special hosts for T.gondii
Cats
Protozoan parasited mainly occurs by
undercooked meat
(particularly, pork, lamb, and
Toxoplasmosis is (severity)
Most infected people are never aware that they are playing host to T.
gondii
However, toxoplasmosis can be a very serious disease for those having
weakened immune systems and infants (parasite may be
transmitted during pregnancy).
Amoebic dysentery is caused by
food contaminated with the cysts of a protozoan parasite ( Entamoeba
histolytica
Trichinosis nematodes are worms of the genus
Macroorganisms
are worms of the genus Trichinella that cause the
disease trichinosis
How can you get Trichinella nematodes and their specificity , and severity and transmission
. Their larvae may be ingested in undercooked
meat , primarily pork, and develop into worms 3 mm long) in the
intestines.
The female worms then produce more larvae that can end up in the
bloodstream.
The severity of trichinosis depends on the number of larvae initially
ingested.
Trichinosis can be prevented by proper cooking , which destroys the
larvae.
Trichinosis is mainly a problem in parts of the world where pigs are
fed garbage or raw meat.
Anisakis are
is another genus of parasitic nematodes (i.e., worms) that can cause
a foodborne illness ( anisakiasis ), specifically in foods of marine origin .
How anisakis are transmitted and how can be avoided
Their larvae may be ingested in raw (or lightly pickled/salted) saltwater
fish as well as raw shellfish and can cause very severe intestinal
symptoms.
Anisakiasis is very effectively prevented by freezing of marine products
that are to be consumed raw,* which destroys the larvae.
* Blast frozen to 35 C or below for 15 hours or regularly frozen to 20 C
or below for 7 days
However, even when larvae of anisakis are destroyed by freezing they can trigger ___
allergic response in some individuals.
Food stability of milk at room temperature
1 day
Food stability of meat/fish at room temperature
1-2 days
Food stability of leafy vegetables at room temperature
1-2 days
Food stability of fruits at room temperature
1-7 days
Food stability of root crops at room temperature
7-20 days
Food stability of dried seeds,real smoked meat and dried fruits at room temperature
more than a year
The basic job of food scientists and the food industry is to ___
protect food
from spoilage and the public from related health hazards
Food processing/preservation is effectively a means of buying time,
Food processing/preservation is effectively a means of buying time,
thereby minimizing food losses and ensuring food security
With time what happens even to processed foods
very slow chemical reactions will manifest themselves as changes in
color, flavor and/or texture as well as loss of nutrients
means by
which foods can be preserved:
Cold treatment : Growth of microorganisms and deteriorative chemical reactions
are slowed down (refrigeration) or halted (freezing).
Drying/concentration : These processes preserve food by reducing water activity
to prevent microbial growth
Heat treatment : Various types of thermal processes are employed to destroy
microorganisms (canning, pasteurization) or inactivate enzymes (
Newer processes include ohmic heating , microwave processing , and high
pressure processing .
Supplemental or Ancillary Means of Preservation
pH reduction
Sugar/salt
Sugar and salt decrease water activity and draw water out of microbial
cells via osmotic pressure
Food additives
Sodium benzoate is one of a few permitted antimicrobial additives.
Antioxidants protect food components that are susceptible to oxidation.
Smoke (rarely used
Food is preserved by formaldehyde/pyrolysis products in wood smoke as
well as heat and dehydration
How modification of atmospheres work
Controlled atmosphere storage (CAS) and modified atmosphere packaging
(MAP) replace air by N 2 /CO 2 mixtures
Molds can’t grow on jams due to high concentration of sugar
and to the presence of acid in the fruit.
False
