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
