Deck 40: Microbiology of Food

Question 1

The first person to use heating processes to preserve foods was

A) Louis Pasteur.
B) Jacque Monod.
C) Robert Koch.
D) Nicholas Appert.

Answer 1

D

Question 2

Growth of yeasts and molds will be favored in more acidic foods.

Answer 2

True

Question 3

Microorganisms that grow in media with low water availability are called _____________.

Answer 3

xerophilic

Question 4

Which of the following helps preserve foods by controlling microbial access to water?

A) drying
B) addition of salt
C) addition of sugar
D) all of the choices

Question 5

Which of the following represents ways in which canned foods may undergo spoilage?

A) spoilage before canning
B) as a result of underprocessing during canning
C) leakage of contaminated water through can seams during cooling
D) all of the choices

Question 6

To control pathogenic and disease-causing organisms, spices can be fumigated using __________.

A) ammonium gas
B) heavy metals
C) ethylene oxide
D) chlorine gas

Question 7

Ergotism involves microorganism production of

A) thermostable enzymes.
B) hallucinogenic alkaloids.
C) sweeteners.
D) flavoring compounds.

Question 8

Temperature and relative humidity are important intrinsic factors in determining the rate of food spoilage.

Question 9

Nisin

A) is a small amphiphilic peptide that disrupts membrane integrity and function.
B) is a food additive that blocks the growth of some gram positive bacteria.
C) is a bacteriocin produced by some strains of Lactococcus lactis.
D) all of the choices

Question 10

Gamma irradiation has been used to sterilize certain types of foods. There are however, certain limitations on its effectiveness. One of these is that it will only work on

A) moist foods.
B) dry foods.
C) foods that are not in metal cans.
D) It is effective with all foods.

Question 11

Filtration is sometimes used to remove organisms from beer because it has less effect on the flavor than pasteurization.

Question 12

Atmosphere is important in food spoilage; high H₂S tends to reduce spoilage, while high CO₂ tends to increase spoilage.

Question 13

A chemical that is effective in preserving foods with a low pH such as bread is

A) sodium propionate.
B) sodium nitrate.
C) sodium citrate.
D) sodium sulfite.

Question 14

A food spoilage process called __________ results in the release of foul-smelling amine compounds.

Question 15

Which of the following can function better at lower pH?

A) yeasts and molds
B) bacteria
C) viruses
D) protozoa

Question 16

Lysozyme is an important antimicrobial substance found at high levels in which food?

A) fish
B) eggs
C) vegetables
D) fruits

Question 17

A major chemical used to preserve meat products is

A) ethylene oxide.
B) propionate.
C) nitrite.
D) refrigeration.

Question 18

A major organism involved in the production of ergot is

A) Pseudomonas fluorescens.
B) Escherichia coli.
C) Claviceps purpura.
D) Aspergillus niger.

Question 19

The use of plastic film to wrap meat products can result in increased surface growth of microorganisms in part because of exposure to

A) oxygen.
B) N₂ which comprises approximately 78 % of gas in the atmosphere.
C) carbon dioxide.
D) water.

Question 20

Pasteurization of milk

A) is no longer used for food processing in the USA.
B) usually eliminates all disease-causing organisms.
C) is a method for sterilization of food items.
D) reduces microbial growth by decreasing availability of water.

Question 21

Clostridium botulinum and Bacillus cereus are important disease-causing microorganisms of food which cause

A) infections.
B) intoxications.
C) cancers.
D) birth defects.

Question 22

The production of natural carbon dioxide by yeasts after a wine is bottled results in

A) sweet wine.
B) dry wine.
C) champagne.
D) brandy.

Question 23

The polymerase chain reaction (PCR) can detect as few as 10 toxin-producing Escherichia coli in a population of 100,000 microorganisms isolated from soft cheese samples.

Question 24

Sometimes __________ beams are used to irradiate foods in place of gamma radiation because the process does not generate radioactive waste.

A) microwave
B) electron
C) magnetic
D) none of the choices

Question 25

The swelling of a food-containing can is frequently due to the production of ___________ by spoilage microbes.

A) oxygen gas
B) nitrogen gas
C) carbon dioxide gas
D) all of the choices

Question 26

Food-borne pathogens are most commonly identified by

A) polymerase chain reaction (PCR).
B) standard culture techniques.
C) pulsed-field gel electrophoresis.
D) none of the choices

Question 27

To control microbial growth in a food, one can decrease water availability by the addition of

A) sugar or salt.
B) gelatin.
C) agar.
D) formaldehyde.

Question 28

Which of the following represents a different principle for food preservation?

A) freeze-drying
B) addition of salt
C) smoking
D) heating

Question 29

If food-borne disease transmission requires ingestion of the pathogen, followed by growth of the organism, and release of toxins in the intestine it is referred to as a food-borne __________.

Question 30

Which of the following is true about molecular methods of microorganism detection in foods?

A) They can be used to detect the presence of a single specific pathogen.
B) They can be used to detect viruses that are not easily cultured.
C) They can be used to detect slow growing pathogens.
D) All of the choices are correct.

Question 31

If food-borne disease transmission does not require growth of the microorganism after ingestion because the toxic substances are already present in the food as a result of previous growth then it is referred to as a food-borne __________.

Question 32

The term radappertization is used to describe food preservation by

A) heat.
B) chemicals.
C) UV irradiation.
D) gamma irradiation.

Question 33

The largest meat recall in U.S. history was prompted by the discovery of contamination by

A) Listeria monocytogenes.
B) Clostridium botulinum.
C) Escherichia coli.
D) Pseudomonas aeruginosa.

Question 34

Aflatoxins are planar, ringed compounds that interact with DNA by ___________ and cause frameshift mutations.

A) substitution
B) rearrangement
C) deletion
D) intercalation

Question 35

Pulsed-field gel electrophoresis can be used to link a particular pathogen associated with disease outbreaks in a specific food source.

Question 36

The process of racking, used in the production of wines, involves

A) depressurizing bottles.
B) addition of sulfites.
C) addition of carbon dioxide.
D) removal of sediments.

Question 37

The conventional low-temperature holding procedure used in the pasteurization of milk involves holding the milk at 62.8^o C for __________ minutes.

A) 5
B) 15
C) 30
D) 60

Question 38

A major organism considered to cause food-borne infection is

A) Salmonella.
B) Staphylococcus.
C) Pseudomonas.
D) Bacillus.

Question 39

A major fungal genus that produces aflatoxin is

A) Rhizopus.
B) Aspergillus.
C) Claviceps.
D) Penicillium.

Question 40

Staphylococcus aureus, once it grows in a food, produces toxins that are not usually inactivated by heating.

Question 41

The process of beer lagering involves

A) carbonation.
B) aging.
C) distillation.
D) none of the choices

Question 42

In breadmaking, yeast growth is usually carried out under ____________ conditions which results in more carbon dioxide production and less alcohol accumulation.

Question 43

Which of the following determines whether or not a wine is considered to be dry?

A) the percentage of alcohol after fermentation
B) the amount of free sugar after fermentation
C) the amount of carbon dioxide after fermentation
D) the type of grape used as a starting material

Question 44

Some fermented dairy products have been suggested to have beneficial effects, including a reduction in the incidence of colon cancer and the minimization of lactose intolerance.

Question 45

Streptococcus thermophilus and Lactobacillus bulgaricus contribute to the flavor of yogurt by producing diacetyl during the fermentation of lactose.

Question 46

Bread products can be spoiled by the growth of Bacillus species that produce

A) gassy doughs.
B) nonrising breads.
C) ropiness.
D) sourdough bread.

Question 47

In all cases, it is necessary for disease-causing microorganisms to grow in a food to result in disease transmission to humans.

Question 48

The holes in Swiss cheese are produced by the metabolic activities of which bacterial genus?

A) Streptococcus
B) Propionibacterium
C) Leuconostoc
D) Lactobacillus

Question 49

Mold-lactic fermentation results in a unique fermented milk consumed in Finland and called ________________.

Question 50

The science of wine production is called

A) enology.
B) rheology.
C) horology.
D) eurology.

Question 51

Sequential growth of microorganisms in which the growth of one organism produces environmental conditions suitable for the subsequent growth of another organism is called ____________.

Question 52

Which of the following microbial genera is used in the production of fermented dairy products?

A) Streptococcus
B) Lactobacillus
C) Leuconostoc
D) all of the choices

Question 53

A microorganism that has been used in the production of sour mash whiskey is

A) Leuconostoc mesenteroides.
B) Lactobacillus delbrueckii.
C) Lactococcus lactis.
D) Saccharomyces cerevisiae.

Question 54

Mashing is a process involving

A) carbonation.
B) protein putrefaction.
C) inoculation.
D) carbohydrate hydrolysis.

Question 55

A major cyanobacterial food source used in many parts of the world is

A) Spirulina.
B) Anabaena.
C) Rhizobium.
D) Gymnodinium.

Question 56

When Lactobacillus acidophilus are sprayed on feed, the cattle that eat it appear to have markedly lower carriage of the pathogenic
E. coli strain O157:H7.