Deck 41: Microbiology of Food

Question 1

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.

Answer 1

B

Question 2

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

Answer 2

D

Question 3

Ergotism involves microorganism production of

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

Answer 3

B

Question 4

A major chemical used to preserve meat products is

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

Question 5

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

Question 6

Which of the following can function better at lower pH?

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

Question 7

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

Question 8

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 9

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 10

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

Question 11

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 12

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

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

Question 13

A major organism involved in the production of ergot is

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

Question 14

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 15

The first person to use heating processes to preserve foods was

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

Question 16

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

Question 17

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 18

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 19

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

Question 20

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

Question 21

A major fungal genus that produces aflatoxin is

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

Question 22

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

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

Question 23

A major organism considered to cause food-borne infection is

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

Question 24

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 25

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 26

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 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

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

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

Question 29

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 30

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 31

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

Question 32

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 33

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

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

Question 34

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 35

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 36

The term radappertization is used to describe food preservation by

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

Question 37

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 38

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 39

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 40

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

Question 41

The process of beer lagering involves

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

Question 42

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.

Question 43

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 44

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

Question 45

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 46

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 47

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 48

The science of wine production is called

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

Question 49

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

Question 50

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

Question 51

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

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

Question 52

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 53

Mashing is a process involving

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

Question 54

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

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

Question 55

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 56

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