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Quality assurance > Unit 3 A and B (microbiology) > Flashcards

Unit 3 A and B (microbiology) Flashcards

1
Q

¨Known hazards in foods: 3 categories

A

🞑 Biological hazards: living organisms

🞑 Chemical hazards

🞑 Physical hazards

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2
Q

Types of biological hazards in food safety

A

¨Biological hazards

🞑 Pathogenic microorganisms

🞑 Viruses

🞑 Parasites

🞑 Others: mad cow’s disease (BSE), Endotoxins

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3
Q

Endotoxins: produced by whim, in what foods are usually found and why dangerous

A

¨Endotoxins are the lipopolysaccharides from gram negative bacteria

¨Endotoxin contents are relatively higher in fermented products and processed meat

¨May compromise the intestinal integrity in vulnerable people.

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4
Q

Most commonly involve 6 pathogenic bacteria

A

🞑 Salmonella

🞑 Campylobacter jejuni

🞑 Escherichia coli O157:H7

🞑 Listeria monocytogenes

🞑 Staphylococcus aureus

🞑 Clostridium

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5
Q

Foodborne infection vs intoxication

A

Eating food contaminated with pathogens that leads to growth of pathogen and cause illness.

Eating food contaminated with the toxins (poisons) produced by bacteria

🞑 Eating food contaminated with other biological or chemical toxins (poisons)

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6
Q

Types of bacteria that usually cause intoxication

A

🞑 Clostridium botulinum, Staphylococcus aureus, Clostridium perfringens, and Bacillus cereus

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7
Q

Types of microorganisms responsible for infection

A

Virus and some bacteria such as Salmonella spp., Listeria monocytogenes, Campylobacter jejuni, Vibrio parahaemolyticus, Vibrio vulnificus, and Yersinia enterocolitica

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8
Q

What is toxin-mediated infection? examples of such organisms

A

Eating food contaminated with pathogens that grow in the body and form toxins (poisons). E.g., Shigella spp. and Shiga toxin-producing Escherichia coli

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9
Q

Can a food product that conforms to the quality requirements conform the safety requirements?

Yes or no?

A

Yes

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10
Q

¨Some people are advocating for raw milk drinking

¨One of their claims is that “raw milk contains natural antimicrobial components that make milk safe”

¨Google those natural antimicrobial components in milk

¨What are they ?

A

Lactoferrin

Lysozyme

Lactoperoxidase

Xanthine oxidase

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11
Q

What does lactoferin and lysozyme do

A

¨Lactoferrin: iron-containing globular glycoprotein

¨Lysozyme: is a glycoside hydrolase that catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D- glucosamine residues in peptidoglycan, which is the major component of gram-positive bacterial cell wall

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12
Q

What does lactoperoxidase and xanthine oxidase does

A

¨Lactoperoxidase: is a peroxidase enzyme that catalyzes the oxidation of several inorganic and organic substrates by hydrogen peroxide

¨Xanthine oxidase: is a nonspecific oxido-reductase involved in purine catabolism, catalyzing the oxidation of hypoxanthine to xanthine and of xanthine to uric acid

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13
Q

As a food scientist, how do you respond to this specific claim?

¨One of their claims is that “raw milk contains natural antimicrobial components that make milk safe”

A

¨No scientific evidence to support the claim that the indigenous antimicrobial compounds in raw milk kill pathogens and ensure raw milk safety

¨Raw milk does not contain high enough concentration of these antimicrobial compounds to exert such an effect

¨In the case of lysozyme and lactoferrin, if high concentrations of these components are observed in raw milk, it is often an indication of cow’s compromised health condition

¨The microflora in raw milk is complex and unpredictable

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14
Q

Strains of E.coli and the differences between them (6)

A

🞑 EPEC: Enteropathogenic E. coli

🞑 EIEC: Entero-invasive E. coli

🞑 STEC: Shiga toxin-producing E. coli is a bacterium that can cause severe foodborne disease. It is related to the E. coli O157:H7

🞑 VTEC: Vero toxin producing E.coli

🞑 ETEC: Enterotoxigenic E.coli

🞑 EHEC: Enterohemorrhagic E. coli

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15
Q

¨First report in 1982, outbreak linked to restaurant: what type of e.coli, to what food was linked, what caused illness

A

¨Four patients with hemorrhagic colitis (bloody diarrhea)

¨Linked to undercooked hamburgers at a fast food chain

¨E. coli O157:H7 produces Shiga toxins

Identified by molecular subtyping of E. coli O157 by pulsed-field gel electrophoresis

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16
Q

Most outbreaks of E.coli associated with what type of food

A

¨Outbreaks are mostly associated with uncooked food of bovine origin or produce contaminated with bovine fecal matters

¨Raw and undercooked ground beef, raw milk, alfalfa sprouts, unpasteurized fruit juices, dry-cured salami, lettuce, fecal contaminated water, game meat, and cheese curds.

¨Peeks in summer months

¨Emerging trends of organic manure/unpasteurized juices ??

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17
Q

Why lettuce can contaminate lettuce? Why dangerous? how can be detected and how to prevent it from going there

A

¨E. coli O157:H7 can migrate to internal locations in plant tissue (lettuce leaf) and become protected from the action of sanitizing agents by virtue of its inaccessibility

¨It may be detected by surface swabbing

¨Need to prevent E.coli in manure and water used for irrigation

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18
Q

Prevention of e.coli getting into food (5)

A

🞑 Washing fruits, pasteurizing fruit juices and addition of sodium benzoate

Washing produce with Chlorinated water

🞑 By maintaining personnel hygiene

🞑 GMP- avoiding cross contamination and fecal contamination in slaughter facility

🞑 Adequate processing of meat products

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19
Q

If a product meets the food safety requirement but not food quality requirement, eventually

a. It will be safe to consume
b. It will always be on the

consumer’s shopping list

c.It will not be on the shelves in grocery stores

A

C

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20
Q

You work for a food processing establishment and they have stricter criteria for product quality than what is set by the government regulations. As a food scientist, which set of rules you should follow?

a. The government’s
b. The employer’s

A

B

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21
Q

International trade encourages adulteration of food products. True/ False

A

False

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22
Q

Food supply chain vs food value chain

A

¨Food Supply Chain: a food supply chain is defined as the set of trading partner relationships and transactions that delivers a food product from producers to consumers.

¨Food value chains or values-based food supply chains: they are strategic alliances between farms or ranches and other supply-chain partners that deal in significant volumes of high-quality, differentiated food products and distribute rewards equitably across the chain.

¨“Consumers want to know the story behind their food and want to support businesses with a social consciousness.”

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23
Q

You and your friends are planning a hiking activity. Which food product will be more convenient for this activity?

a. Canned tuna
b. Tuna fillet

A

A

24
Q

If your friends insist on having tuna fillet every evening during this trip, it will cost

a. More money
b. Less money

A

A

25
Q

After some discussion with your friends, everyone agreed that canned tuna is the “better product” for this trip. This is an example of …… definition of quality.

a. user-based
b. judgmental
c. manufacturing-based
d. value-based

A

User-based

26
Q

Serovas of Salmonella

A

¨Serovars: S. Enteritidis, S. Typhimurium, S. Newport

27
Q

Salmonella causes what types of disease and what symptoms

A

🞑 enteric fever (typhoid), resulting from bacterial invasion of the bloodstream (S.

typhi and S. paratyphi)

🞑 acute gastroenteritis, resulting from a foodborne infection/intoxication (S. enteritidis

phage type (PT) 4

28
Q

Carriers of Salmonella and how it propagates

A

🞑 Reptiles, birds, pigs, horse, cattle

🞑 Transmission is by consumption of contaminated foods of animal origin such as meat or eggs

🞑 Salmonella can invade and survive inside macrophages

29
Q

Prevention of Salmonella

A

¨Avoid raw or undercooked eggs, poultry, meat; unpasteurized milk/dairy

¨Wash foods before eating

¨Maintain high personal hygiene standards

¨Avoid birds and bird drooping in food processing facility

¨Prevent the entry of reptiles (Turtle/snake etc.) in food processing facilities

¨Make sure employees are not asymptomatic carrier of Salmonella

¨Avoid cross-contamination of food

¨Keep uncooked and cooked food apart

30
Q

Why listeria is dangerous? susceptible population, where naturally found?

A

¨Rare but high mortality rate

¨Susceptible population include pregnant, fetus, elderly population

¨Present in soil and other environmental matrix

¨Resistant to refrigeration

31
Q

Where C.jejuni can be found

A

¨Contamination of poultry meat from colonized chickens is considered the major source

¨Unpasteurized milk is a well-documented cause of several outbreaks of campylobacteriosis

32
Q

How C. jejuni can be prevented? why it is dangerous?

A

¨They rapidly and effectively respond and adapt to environmental stresses such as antimicrobials, temperatures, dehydration, bacteriophages etc.

¨Sufficient heating of red meat products, which are relatively infrequently contaminated with low numbers of Campylobacter, will eliminate this risk of human infection

33
Q

What is dagerous is S. aureus?

A

Toxin

34
Q

Incubation period of S.aureus

A

2-6 hours

35
Q

Symptoms of S.aureus intoxication

A

¨Severe vomiting, abdominal cramping and prostration, sometimes diarrhea

36
Q

Foods implicated in S.aureus

A

¨Custard or cream-filled baked goods, ham, poultry, eggs, potato salad, cream sauces, sandwich fillings

37
Q

Keeping raw milk at 0-4°C will not protect consumers from Listeria monocytogenes

True/False

A

True

38
Q

foodborne enteric viruses of known epidemiological significance

A

hepatatis A

rotavirus

norovirus

39
Q

Most severe of the foodborne viral diseases, approx 5% of cases of foodborne illnesses. What virus?

A

Hepatitis A

40
Q

Important cause of infant diarrhea world-wide with relatively high mortality

🞑 Foodborne transmission rare

What virus?

A

Rotavirus

41
Q

🞑 Leading cause of viral foodborne disease; leading cause of foodborne disease

🞑 20-80% of cases are transmitted by contaminated foods

What virus?

A

Norovirus

42
Q

What is the role of personal hygiene in HuNoV

A

Role of personal hygiene (>56%)

43
Q

¨HuNoV persistence

A

4°C/60 days (<50% inactivation)

🞑 Complete inactivation 21°C/14-28 d (or more), 37°C/1-10 d

44
Q

¨HuNoV resistance to sanitizers

A

🞑 Hypochlorite, iodine, glutaraldehyde effective

🞑 Quats, ethanol, anionic detergents less effective

45
Q

¨HuNov resistance to processes

A

🞑 Heat

🞑 Ionizing radiation

🞑 High pressure

46
Q

What does Foodborne Diseases Active Surveillance Network do

A

¨the Foodborne Diseases Active Surveillance Network (FoodNet) of CDC’s Emerging Infections Program monitors the incidence of laboratory-diagnosed infections caused by eight pathogens transmitted commonly through food at 10 U.S. sites.

47
Q

What are those eight pathogens that FoodNet monitors

A

¨Campylobacter

¨Cyclospora

¨Listeria

¨Salmonella

¨Shiga toxin-producing Escherichia coli (STEC) O157 and non-O157

¨Shigella

¨Vibrio

¨Yersinia

48
Q

¨What are the factors that contribute to the emergence of foodborne diseases?

A

¨Rapid population growth and a demographic shift towards an ageing population.

¨An increasingly global market in vegetables, fruit, meat, ethnic foods

¨An increasingly transient human population carrying its intestinal flora worldwide.

¨Changing eating habits, such as the consumption of raw or lightly cooked food, and the demand for exotic foods, such as bushmeats.

¨The shift from low- to high-protein foods, especially in emerging economies

¨Higher proportions of immunologically compromised individuals

(aging population/HIV)

¨Changing farming practices, for example intensification to produce cheaper food or a shift to free-range/organic animal production to respond to consumer welfare concerns.

Climate change, for example bringing novel vectors into temperate regions or temperature-associated changes in contamination levels

49
Q
A
50
Q

¨Several human parasites can be transmitted by foods. Most common human parasites include:

A

Parasitic protozoan species (e.g., Entamoeba histolytica, Giardia lambia, Cryptosporidium parvum)

🞑 Parasitic worms (e.g., Ascaris lumbricoides, Taenia solium, Trichinella spiralis)

51
Q

Where cestodes (tapeworms) can be found

A

🞑 Meat and fish may contain larval tapeworms that can develop into adults in the human intestine.

🞑 The pork (Taenia solium) and beef tapeworms (T. Saginata) are the best known

🞑 Tapeworm eggs may be present on fruits or vegetables fertilized with human wastes or washed with contaminated water.

52
Q

Source of nematodes (round worms) and examples (3)

A

🞑 Trichinella, Ascaris, and Anisakis Angiostrongylus, and Gnathostoma

🞑 Source: fecally contaminated water or vegetables

53
Q

Control of parasites (3)

A

¨Agriculture practices (GAP)

¨Sanitation and Hygiene (GMP)

¨Processing parameters (HACCP)

54
Q

Examples of GAP and how they can help to cope with parasites

A

🞑 Animal husbandry practices that prevent parasites infection of animals

🞑 Proper inspection of pork, beef, and fish

🞑 Avoid using contaminated water for irrigation

55
Q

How GMP can help to cope with parasites?

A

🞑 Proper disposal of human and animal wastes

🞑 Control of flies, cockroaches, and other insects

🞑 Thorough washing of raw vegetables and fruits to remove eggs and larvae of parasites

56
Q

How HACCP can cope with parasites?

A

🞑 Adequate cooking (e.g Cooking fish for 10 min at 60°C or 7 min at 70°C will kill Anisakis)

🞑 Freezing of fish below -30 for more than 15 hours (for fish to be consumed raw)

🞑 Soaking of vegetables in a 1.5% bleach solution

Quality assurance (6 decks)

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