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BIOL 2604 > Food Microbiology > Flashcards

Food Microbiology Flashcards

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
Q

Illness passed from infected food service workers and cases per year

A

-Noroviruses = 9,200,000
-Real #1 virus

26
Q

What does O mean in this E. coli O157:H7?

A

-O is the antigen

27
Q

Food Infection

A

-ingestion of food that contains a pathogen
-the pathogen grows inside the human, causing disease
-MAY or MAY NOT be “self-limiting”

28
Q

Food Poisoning = Food intoxication

A

-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
Q

What does Self-limiting mean?

A

-means that symptoms pass in short time (days)

30
Q

Enterotoxin

A

-food intoxication
-diarrhea symptoms

31
Q

Staphylococcus aureus

A

-heat stable enterotoxins
-Nausea, vomiting, diarrhea (1-6 hours)
-Egg/meat salads, salad dressing, desserts, meat, improper heating/cooling

32
Q

Clostridium perfringens

A

-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
Q

What is CPE

A

-C. perfringens enterotoxin

34
Q

Step sin C. perfringens acute food poisoning

A

-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
Q

Does heating drive off O2?

A

-Yes

36
Q

What type of cell does contaminated C. perfringens food contain?

A

vegetative bacterial calls

37
Q

What do spores want to do?

A

-Spread

38
Q

What is Clostridium botulinum: Adult botulism?

A

-food poisoning/intoxication
-neuron toxin
-Spore former (can survive cooking)
-Botulinum toxin (heat labile), cosmetic application

39
Q

Number of cases, Symptoms and Treatment for Clostridium botulinum

A

-Few cases, but high mortality
-Paralysis (18-24 hours), can last for months
-Treatment = ventilation and antitoxin

40
Q

Is the US good at food safety?

A

-Yes

41
Q

What is Clostridium botulinum: Infant botulism?

A

-Grows in intestines
-often from honey, can be environmental
-due to immature immune system and immature intestinal flora
-Hypotonia

42
Q

Hyptonia

A

-floppy head syndrome
-decreased muscle tone

43
Q

What is the treatment for Clostridium botulinum: Infant botulism

A

-Treatment = ventilation and tube feeding
-Self-limiting 3-6 weeks

44
Q

Salmonella enterica

A

-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
Q

What type does Salmonella enterica produce?

A

-produce endo, exo, and enterotoxins

46
Q

Enteroclitis

A

-headache, chills, vomiting, diarrhea, and fever for 8-48 hours

47
Q

Salmonella enterica subtype Typhi

A

-causes Typhoid fever
-15% mortality when untreated

48
Q

Types of Escherichia coli

A

-Enterohemorrhagic (EHEC)(O157:H7)
-Enterotoxigenic (ETEC)
-Enteropathogenic (EPEC)
-Enteroinvasive (EIEC)

49
Q

Enterohemorrhagic (EHEC)(O157:H7)

A

-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
Q

Enterotoxigenic (ETEC)

A

-Enterotoxins (heat labile)
-Traveler’s diarrhea (watery)

51
Q

Heat labile

A

-sensitive or destroyed in heat

52
Q

Enteropathogenic (EPEC)

A

-children
-non-invasive
-no toxins

53
Q

Enteroinvasive (EIEC)

A

-Invasive, survives in phagocytes
-Watery to blood diarrhea

54
Q

What is Campylobacter species caused by and what are its symptoms?

A

-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
Q

How much bacteria is need to infect for Campylobacter species and what does it infect?

A

-10^4 bacteria required for infection
-Self-limiting 7-10 days
-invades intestinal epithelium, causes inflammation
-Number one bacterial food poisoning

56
Q

Listeria monocytogenes

A

-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
Q

psychrotolerant

A

cold tolerant

58
Q

What does Listeria monocytogenes do?

A

-intracellular pathogen
-polymerizes host cell actin to drive motility, breaks from one cell into another

59
Q

What rare diseases come from Listeria monocytogenes?

A

-Bactermia
-Meningitis

60
Q

Norovirus

A

-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
Q

What are the top five factors that contribute to foodborne disease outbreaks in the US?

A

-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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