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BIOL 2604 > Food Microbiology > Flashcards

Food Microbiology Flashcards

(61 cards)

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1
Q

Microbial Growth and Food Spoilage

A

-Perishable food: fresh food
-Semi perishable food: potatoes and nuts
-Stable or Nonperishable food: flour and sugar

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2
Q

What is a major factor in food falling in certain categories?

A

-Water content
-more water, more perishable

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3
Q

Does microbial growth always mean spoilage?

A

-NO
-fermentation often preservers food

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4
Q

Methods of Food Preservation

A

-Growth inhibition method
-Killing of microbes

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5
Q

Growth inhibition methods

A

-Storage temperature
-Acidity
-Decreased water activity
-Chemical preservatives

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6
Q

Storage Temperature

A

-refrigerate = 4°C, psychrophilic organisms can still grow
-Freeze = -20°C, long term

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7
Q

Acidity

A

-pickling
-In some cases is a result of fermentation
-Acetic acid = vinegar

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8
Q

Decreased water activity

A

-drying
-add sugar, add salt

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9
Q

Chemical preservatives

A

-Some are not to bad
-Other are very bad for your health

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10
Q

Killing of Microbes

A

-Canning
-Irradiation
-Pasteurization

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11
Q

Canning

A

-Sterilization
-heating time requires to kill bacterial spores
-green beans, beans, peas
-some things cannot be canned because they disintegrate when heated to sterilizing temperature

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12
Q

What should a can look like?

A

-Good=indent
-Not good=no indent, gas has formed
-Swelling=lots of gas!
-dropped=gas created pressure and can exploded

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13
Q

Irradiation

A

-decreases viable counts
-may not sterilize
-Co, gamma

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14
Q

Pasteurization

A

-decreases viable count
-does not sterilize

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15
Q

Useful microbes in food

A

-fermented food
-sugars are converted to alcohol or acid
-fermentation products are inhibitory to other organisms
-In some cases, other antimicrobial compounds are produced like simple antibiotics

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16
Q

Dairy foods: cheese, yogurt, and buttermilk

A

-Lactic acid
-Lactococcus
-Lactobacillus
-Streptococcus thermophilus
-Propionibacterium = Swiss chesses

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17
Q

Alchol

A

-Zymomonas
-Saccharomyces

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18
Q

Baking

A

Saccharomyces cerevisiae

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19
Q

Meat products

A

-Pediococcus
-Lactobacillus

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20
Q

Vegetables

A

-Leuconostoc
-latic acid bacteria

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21
Q

Vinegar

A

-Acetobacter=acetic acid

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22
Q

Soy Sauce

A

-Aspergillus = fermentation of fungi

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23
Q

Common causes of foodborne illness in US

A

-Passed from animal carries or environmental
-Passed from infected food service workers

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24
Q

Illness passed from animal carries or environmental sources and cases per year

A

-Campylobacter species = 2,000,000
-Salmonella species = 1,340,000
-Clostridium perfringens = 248,000
-Staphylococcus aureus = 185,000
-E. coli O157:H7 = 63,000 (hemorrhagic)

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25
Illness passed from infected food service workers and cases per year
-Noroviruses = 9,200,000 -Real #1 virus
26
What does O mean in this E. coli O157:H7?
-O is the antigen
27
Food Infection
-ingestion of food that contains a pathogen -the pathogen grows inside the human, causing disease -MAY or MAY NOT be "self-limiting"
28
Food Poisoning = Food intoxication
-Ingestion of food that contains a toxin -Generally the microbe that produced the toxin does not grow inside the human -symptoms are result of the performed toxin -Often self -limiting
29
What does Self-limiting mean?
-means that symptoms pass in short time (days)
30
Enterotoxin
-food intoxication -diarrhea symptoms
31
Staphylococcus aureus
-heat stable enterotoxins -Nausea, vomiting, diarrhea (1-6 hours) -Egg/meat salads, salad dressing, desserts, meat, improper heating/cooling
32
Clostridium perfringens
-Spore former (can survive cooking) ->10^8 cells ingested -sporulation occurs in small intestine -produces CPE -Diarrhea and cramps (7-15 hours) -Chili, salads containing meat, improper heating/cooling
33
What is CPE
-C. perfringens enterotoxin
34
Step sin C. perfringens acute food poisoning
-Contaminated food is cooked and spores survived cooking -germination occurred when food cooled down -Cell grew rapidly in warm, anaerobic food -Person eats contaminated food -Bacteria pass from stomach to SI -pH shock induces sporulation -Sporulation and enterotoxin (CPE) synthesis in SI -bacteria breaks open releasing spore and toxin -CPE binds to epithelial cell, causes diarrhea and dispersion of spore
35
Does heating drive off O2?
-Yes
36
What type of cell does contaminated C. perfringens food contain?
vegetative bacterial calls
37
What do spores want to do?
-Spread
38
What is Clostridium botulinum: Adult botulism?
-food poisoning/intoxication -neuron toxin -Spore former (can survive cooking) -Botulinum toxin (heat labile), cosmetic application
39
Number of cases, Symptoms and Treatment for Clostridium botulinum
-Few cases, but high mortality -Paralysis (18-24 hours), can last for months -Treatment = ventilation and antitoxin
40
Is the US good at food safety?
-Yes
41
What is Clostridium botulinum: Infant botulism?
-Grows in intestines -often from honey, can be environmental -due to immature immune system and immature intestinal flora -Hypotonia
42
Hyptonia
-floppy head syndrome -decreased muscle tone
43
What is the treatment for Clostridium botulinum: Infant botulism
-Treatment = ventilation and tube feeding -Self-limiting 3-6 weeks
44
Salmonella enterica
-Typhimurium = odd -eggs, meat, dairy products -enterocolitis -live bacteria shed for several weeks -cells grow inside phagocyte and spread to other cells -self-limiting
45
What type does Salmonella enterica produce?
-produce endo, exo, and enterotoxins
46
Enteroclitis
-headache, chills, vomiting, diarrhea, and fever for 8-48 hours
47
Salmonella enterica subtype Typhi
-causes Typhoid fever -15% mortality when untreated
48
Types of Escherichia coli
-Enterohemorrhagic (EHEC)(O157:H7) -Enterotoxigenic (ETEC) -Enteropathogenic (EPEC) -Enteroinvasive (EIEC)
49
Enterohemorrhagic (EHEC)(O157:H7)
-verotoxin -Hemorrhagic/bloody diarrhea, kidney failure -Undercooked (ground) meat -Jack in the box out break 1991 -Recently, fresh fruits and vegetables contaminated with animal feces (cow) or water runoff from animal lots
50
Enterotoxigenic (ETEC)
-Enterotoxins (heat labile) -Traveler's diarrhea (watery)
51
Heat labile
-sensitive or destroyed in heat
52
Enteropathogenic (EPEC)
-children -non-invasive -no toxins
53
Enteroinvasive (EIEC)
-Invasive, survives in phagocytes -Watery to blood diarrhea
54
What is Campylobacter species caused by and what are its symptoms?
-caused by poultry, pork, shellfish, surface waters -normal intestinal flora in chickens and turkeys -Symptoms: diarrhea with watery/bloody stool, sterility, and abortions in animals -high fever, headache, malaise, nausea, cramps
55
How much bacteria is need to infect for Campylobacter species and what does it infect?
-10^4 bacteria required for infection -Self-limiting 7-10 days -invades intestinal epithelium, causes inflammation -Number one bacterial food poisoning
56
Listeria monocytogenes
-found in many water and soil samples, contamination during food processing -acid and salt tolerant, psychrotolerant -meat, diary, fresh produce -most infections are minor and not even recognized -acute rare, but deadly -infects developing fetas, 90% mortality rate
57
psychrotolerant
cold tolerant
58
What does Listeria monocytogenes do?
-intracellular pathogen -polymerizes host cell actin to drive motility, breaks from one cell into another
59
What rare diseases come from Listeria monocytogenes?
-Bactermia -Meningitis
60
Norovirus
-RNA virus -Stomach flu or viral gastroenteritis -fever, chills, headache, muscle aches -self limiting = 1-2 days -highly contagious and passed via contact with infected people or contaminated surfaces or food -cruise ships
61
What are the top five factors that contribute to foodborne disease outbreaks in the US?
-Inadequate refrigeration (47%) -Food prepared to far in advance (21% -Infected person with poor personal hygiene (21%) -Inadequate cooking (16%) -Inadequate holding temperature (16)

BIOL 2604 (17 decks)

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