Lecture 4: Food Microbiology Flashcards
What are Microbes?
Microscopic organisms
What are the most important microbes associated with food?
- Virus
- Bacteria
- Yeasts
- Molds
- Parasites
Where are Parasites found in food?
Found in raw and under-cooked foods.
What is Trichinella?
It is a parasite that is found in wild and some domestic pigs within their muscles
True or false:
Parasites can be passed on from person - to - person contact
True
How are viruses transported?
Through food between hosts.
Do viruses multiply in food before reaching the host
No they do not, although they can remain on food if it is insufficiently cooked.
What is Norovirus?
-Leading cause of Gastroenteritis, ie the stomach flu.
What is Hepatitis A Virus?
- Causes liver disease
- Spread primarily through food or water contamination by stool from a infected person
- can be prevented by vaccination.
Molds grow in a tangled mass of _____
Mycelium
Molds replicate by spores called ____, visable at the top of the _______
Conidia
Hyphae
How do Molds reproduce?
They release spores into the air.
What food is made with mold?
Cheeses such as blue cheese.
Soy sause
Are molds known to cause gastrointestinal distress?
No they are not, although they can cause allergic reactions and respiratory problems.
What is Yeast?
A type of Fungi that is predominantly a spoilage organism.
What is a cool fact about Yeast?
Largest, still single cell organism.
What is the primary organism implicated in food-borne disease?
Bacteria, either on their own or through their toxins
What are the three most common bacteria found in food that are BAD BAD.
- Salmonella spp.
- Colstridium botulinum
- Staphylococcus aureus
Are all bacteria bad?
No, probiotics are great!
with many being involved in the fermentation reactions within the lactic acid cycle.
Bacteria Exist as ________ cells or spores
Vegetative
When do Bacterial spores germinate?
Under favorable conditions
True or false:
Bacterial spores are highly resistant formations that are thermoduric and acid resistant
True
What is the focus of Food sterilization?
To kill thermoduric spores
What environmental factors determine which microbs grow?
- Nutrient availability
- pH/acidity
- Temp
- [Oxygen]
- Water activity
- Time
True or false:
Both plant and animal foods support the growth of pathogens
True
True or false:
there is a microorganism to utilize every type of food component
True.
Almost all foods fall below __ pH
7
Most pathogens can grow within the range of __ pH to __pH
4.6 to 9.0
What is a High acid food?
pH less than or equal to 4.6
What is a low acid food?
pH greater than 4.6
Very acidic or sour foods discourage the _____ of many microorganisums
growth
Foods that support the growth of bacteria in the temperature danger zone are called what?
Potentially hazardous foods
What is the temperature danger zone?
between 5c to 60c
this zone experiences rapid bacterial growth.
What temperature will Psychrophiles grow best at?
<10C
What temp will Mesophies grow best at?
26-35C
What temp will Thermophiles grow best at?
> 40C
What are Psychrotrophic microbes?
microbes that can tolerate low T, can grow under refrigeration
What are Thermophic microbes?
Microbes that can tolerate high T, can grow (55-60C)
Bacteria will replicate rapildly within their ideal temp, how fast do they replicate?
they double roughly every 20min
What are Obligate aerobes?
Are usually associated with surface growth
What is an example of a Obligate aerobe?
Bacillus spp.
What are Microaerophilic microbes?
bacteria that prefer limited oxygen conditios
What is an example of Microaerophilic microbes?
Campylobacter sp.
What is a indifferent microbe?
bacteria grow in or without presence of oxygen
What is an example of a indifferent microbe?
lactobacillus sp.
What are Faculative anaerobes?
Bacteria that grows well in oxygen but can live in anaerobic conditiosn
What is an example of a Faculative anaerobes?
Escherichia
What are obligate anaerobes?
Bacteria grow where oxygen is absent
What is an example of a obligate anaerobes?
Clostridium sp.
What is the minimum a(w) for microbial growth?
Bacteria: 0.85
Yeasts: 0.65/0.80
Molds: 0.65
How can you tell if microbial growth has occurred?
- Signs of gas or acid production; off odors.
- Mold
- Yeast colonies
What is the general rule around food spoilage?
When in doubt, throw it out.
What is a Physical Hazard within food-borne illnesses?
Unwanted objects or matter in a food item which may cause illness or injury to the consumer.
What is a Chemical Hazard within food-borne illnesses?
Chemical materials (sanitizes, pesticides, cleaners) contaminate food
What is a Biological Hazard within food-borne illnesses?
Pathogens or toxins in food causing illness.
What are Disease-causing microorganisms called?
Pathogens
What is “Food Intoxication?”
Bacterial toxin or chemical compound toxic to humans is ingested
- short onset illness
What is an example of Food intoxication?
Staphylococcus
What are “Food infections”?
High numbers of pathogens in the food are ingested
- longer onset illness
What is an example of a food infection?
Bacillus Cereus
What is a “toxin-mediated infection”?
Pathogen from food produces toxin after ingestion
What is an example of a “Toxin-mediated infection?
Escherichia Coli
How is the Norovirus transmitted?
Transmitted either by drinking contaminated food or water.
or
By passing from person to person often through food handling.
What are the common food carriers of the Norovirus?
Sandwiches
Salads
RTE foods
What are the symptoms of the Norovirus?
Stomach flu
Vomiting and diarrhea.
What are the high risk foods of “Listeria monocytogenes”
- refrigerated smoked fish
- Raw or unpasteurized milk
- soft or unpasteurized cheese
- Ready to eat meals
What makes getting rid of Listeria monocytogenes difficult?
It resits heat, salt, nitrate, low T, and acidity
How is Salmonella sp transmitted?
Through the consumption of contaminated food or beverages, mainly animal products.
What are the high risk foods of Salmonella sp?
Raw or under-cooked poultry,ground beef, and eggs.
- unpasteurized dairy
- raw fruits and vegetables
What are the symptoms of Salmonella sp?
Causes Salmonellosis (fever, diarrhea, and cramps)
What is the common source of Campylobacter jejuni?
- Raw or undercooked meat (poultry, beef, pork, and lamb)
- Raw milk, dairy products and vegetables
- Shellfish
- untreated drinking water
What are the symptoms of Campylobacter jejuni?
Fever
Diarrhea
Cramps
Where is “Escherichia coli O157:H7 found?
E.coli live naturally in the intestine of cattle, poultry, and other animals.
Do all varieties of Escherichia coli O157:H7 cause disease?
No
How do you contract Escherichia coli O157:H7?
Through the exposure or consumption of:
- raw and under-cooked meat (handling or eating)
- contaminated raw fruits and vegetables
- untreated water
- unpasteurized milk, milk products and apple juice/apple cider.
What are the symptoms of Staphylococcus aureus?
Nausea, diarrgea, vomiting, cramps
How do you contract Staphylococcus aureus?
Contact through food handlers, milk and cheese along with unsafe kitchen habits.
(licking the spoon and putting it back in)
What is one of the worst complications caused by E. coli O157:H7?
Hemolytic Uremic Syndrome (HUS).
What is Hemolytic Uremic Syndrome (HUS)?
• E coli in the digestive tract produce toxins that enter the
bloodstream.
• Ultimately may end in kidney failure.
Why and how will new challenge to food safety continue to emerge?
- New and emerging bacteria, toxins, and antibiotic resistances
- Changes in consumer preference
- changes in environment
- Microbes are globally spread
Why should you never thaw food at room temperature?
The outside of the food will reach the danger-zone of microbial growth far before the inner core of the food is thawed.
True or false:
More than 50% of all food borne illness outbreak result from food that was eaten at home.
False:
it is only 20%
Of the following, what was found to have the highest concentration of Microbes?
- Knife block
- Food storage container with rubber seal
- Rubber spatula
- Blender
- Refrigerator ice dispenser
- Can opener
- Refrigerator meat compartment
- Refrigerator vegetable compartment
- Microwave keypad
- Refrigerator water dispenser
It was the Refrigerator water dispenser.
What are the four main causes of food borne ilness associated with the food industry?
- Contaminated raw foods
- Insufficient processed foods
- processed foods are exposed to bacteria
- Inappropriate personal hygiene among food handlers, along with inappropriate cleaning and sanitizing of equipment
What are some of the controls the food industry has to ensure safety against biological hazards.
- Temperature management
- Avoidance of corss-contamination
- Enforcement of personal hygiene among food handlers
- Inspection and enforcement (in-house and government)
What is the most important thing possible within food safety?
Wash all equipment that touches food, no matter the food.
What is the main focus of the food industry around food safety.
The Focus in on Prevention.
What are the standard food production procedures to produce safe, and high quality food.
GMP’s (Good Manufacturing practices)
and
SOP’s
What are Good Manufacturing Practices?
- Good Hygiene
- Prevent cross-contamination
- Identification and control processes
(Standard Operating Procedures) - Ensure that operators are trained to follow SOP’s and GMP’s
- System available to recall from sale.
What is a HACCP?
Hazard Analysis Critical Control Points
- Prevention approach of the food industry to enhance food safety.
What is the flow chart of a HACCP process?
- Steps of food production are identified
- Critical points and potential hazards at each points are identified
- Preventative measures, limits and monitoring procedures are developed
- Record-keeping and plans of corrective action are established.
What is the purpose of intentional food fermentation?
- For preservation and for the creation of new products.
What dose intentional fermentation generate?
distinctive:
- Flavors
- textures
- Featured attributes
What is the most well known fermented food? and most common form of intentional fermentation?
Lactic acid fermentation of milk
What is the flow chart for generating fermented food?
- Nutrients in food
1. 5: Metabolism by fermenting microorganism - Fermentation products added
2. 5: Interaction of fermentation product with food - Change in good characteristics
What are some examples of Lactic acid bacteria based fermentation?
Pickles
Olives
Cheese
How do you make swiss cheese?
With propionic acid bacteria
What are some examples of yeast based fermentation?
Beer
wine
whiskey
How do you make coffee and chocolate
With the addition of acetic acid bacteria and lactic acid bacteria
What are some examples of mold based fermentation?
Blue cheese
What are some examples of Acetic acid bacteria based fermentation?
Vinegar, cider
What is Controlled Fermentation?
Controlled microbial growth by using starter cultures (Specific strains of microbes)
What is the process of actually conducting controlled fermentation?
- Introduce and encourage the growth of microbes under controlled conditions
What is the result of controlled fermentation?
Results in consistent quality of the final product
Who supplies the microbes needed for controlled fermentation?
They are supplied by industrial companies
What is one of the main methods of controlled fermentation?
pH control
- inhibits other undesired microbes through the addition of acid, or the production of acids by the microbes.
What is the purpose of salt within controlled fermentation?
It is added in pickled and meat products.
This is due to the fact that brine with greater than 10% salt inhibits spoilage microbes, allowing lactic acid microbes to thrive.
What role dose Temperature play in Controlled fermentation?
- Depending on T, different microbes dominate fermentation
true or false:
There is a benefit to your gut biome when you ingest live bacteria.
True.
True or false:
Genetically modified bacteria could secrete appetite
suppressing metabolites
True
Foods can be described bu their degree of processing
- minimally processed
- basic processed
- Moderately processed
- Highly processed
Food processing adds value to food.
What is a value added commodity?
Food to which
value has been added through special growing,
processing or packaging techniques
What are the three principle preservation techniques? and what is the goal of these techniques?
Alteration of environment to prevent mirobe growth:
- freezing
- drying
Destroy microbial viability
- Canning
What is the preservation principle of drying?
Water removal
What is the preservation principle of freezing?
Water is unavailable (used up as ice, and microbs cannot grow at that temp)
What is the preservation principle of refrigeration?
Lower the temperature to limit microb growth
below optimum of growth
What is the preservation principle of Heat sterilization?
Viable microbes are inactivated
they are destroyed, and then packaged the product in a container to prevent re-contamination.
What is the preservation principle of Smoking/baking/pasteurization?
Inactivation of some microbes, and the activation of others.
What is the preservation principle of fermentation
Acid producing microbes will lower the pH and limit spoilage microbes
What is the preservation principle of pickling/salting/sugaring
Add acid, salt or sugar to tie up the water and limit microbe growth.
What dose it mean to reduce Microbial Load?
the removal of microbes from food prior to processing?
What is an example of (GMP) Good Manufacturing Practices?
keep microbes and gross contaminants out of food.
How do industries control the atmosphere around food to prevent spoilage?
They remove oxygen and add +/- nitrogen and/or carbon dioxide.
What is the some of the chemical additives used to limit spoilage?
- Butylated hydroxy anisole (BHA)
* Sodium benzoate (NaC6H5CO2)
