Food Micro Flashcards
What is the “F” value?
Minutes required to destory a given number of microbes at a given temperature
Sauerkraut results from what kind of fermentation process?
Lactic Acid
What is kefir?
Milk fermentation by yeast and lactic acid bacteria
What is the name for the phenomenon which draws water into materials?
Capillary action (surface tension)
What does MPN stand for?
Most probable number
What are the microorganisms that prefer to live without oxygen?
anaerobic
What is the circular, single stranded exonuclear DNA known as?
Plasmid
A polypeptide bacteriocin produced by some Streptococcus lactis strains is called what?
Nisin
The D value of green peas is 0.2 minutes. What is the F value at 250 F?
12D so 2.4 minutes
What is the perigo factor?
Substance formed in heated foods containing nitrite and it has antibacterial activity
Which of the following types of organism is not defined by temperature ? A. Psycrophiles B.Thermophiles C.Mesophiles D. Thermoduric
Thermoduric
What are halophiles?
Microorganisms that can survive high concentrations of salt
What yeast is in soy sauce production?
Zygosaccharomyces rouxii and Torulopsis spp
Which bacteria is added to Swiss cheese for eye formation?
Propionibacterium shermanii
What is the term for a complete set of genetic material in an organism?
Genome
What term describes plants that can grow in high-salt environments?
Halophytes
What is the scientific term for a n increase in the size of the cells in an organism?
Hypertrophy
What two lactic acid thermophilic bacteria are inoculated into pasteurized milk in the fermentation process that yields yogurt?
Streptococcus Thermophilus and Lactobacilus Bulgaricus
Name and describe the component of pineapple that will make your mouth sore and give you a stomach ache if you eat too much of it.
Bromellin- a proteolytic enzyme
For what foods has irradiation been approved as a preservation method?
Poultry, Pork, and Spices
What is the white colony growth of molds called?
Mycelium
What are the four main stages in the life cycle of the Drosophila fruit fly?
Egg, Larva, Pupa, Adult Fly
Which of the following molds has a foot cell: Aspergillus Penicillium, or Alternaria?
Aspergillus
Molds grow in an oxidation-reduction potential of?
Positive Values
What do aerogenic bacteria produce?
Gas
What do microaerophiles require for growth?
Some oxygen
Why are plates for total plate count incubated upside down?
To prevent condensation from dripping on the surface of the agar.
Sporeforming aerobic rods occur as what?
Psychrotrophs, Mesophiles, and Thermophiles
What are Xerophilic molds?
grow in low water activity environments
In what types of foods are thermophilic sporeformers of primary concern?
Aseptically processed low acid foods.
What is the form of aflatoxin excreted in milk?
M1 and M2
What is the order of heat resistance for microorganisms?
Bacterial spores are more heat resistant than bacterial vegetative cells, yeast cells, and molds.
Why was Schwan’s ice cream recalled from the marketplace in October of 1994?
For presence of Salmonella Enteriditis
What does obligate mean for microorganisms?
Absolute Requirements
For what pathogen(s) is/are there a zero tolerance in ready to eat processed foods?
Salmonella species and Listeria monocytogenes
What does HACCP stand for?
Hazard Analysis and Critical Control Points
Which of the following is not a microbial preservative? (1) Nisin (2) Sodium Propionate, (3) Sodium Alginate, or (4) Nitrite
Sodium Alginate
Name two mycotoxins produced by Fusarium species.
Zearalonone, Trichothecenes, Fumonisins, and Fusarin
What are coliforms?
Coliforms are gram-negative, aerobic to facultatively anerobic, nonsporeforming rods that ferment lactose to gas within 48 hours at 35⁰C.
Which microorganisms produce endospores?
Bacillus and Salmonella
What are the dominant spoilage microflora of fish?
Pseudomonas, Flavobacterium, and Moraxella
What does high total counts in dehydrated foods indicate?
Poor raw materials, Improper processing techniques, and poor sanitation.
What bacteria can cause flat sour in foods?
Bacillus stearothermophilus
What are the five steps used in the traditional isolation of Salmonella species?
- Preenrichment 2.Selective Broth Isolation
3. Selective Plate Isolation 4.Biochemical Test 5.Serology
What food-borne parasite can be found in hogs eating uncooked food waste?
Trichinella Spiralis
When is a microorganism considered dead?
When it fails to grow or reproduce in or on media.
What are flagella?
Appendages that allow microbes to be motile.
what are the four most important spoilage microorganisms associated with refrigerated meats?
Pseudomonas spp., Flavobacterium spp., Acinetobacter spp., and Moraxella spp.
What causes greening of luncheon type meats?
Lactobacillus Viridescens
What is the minimum pH of growth for most Gram-negative aerobic bacteria?
pH 5.3
How is the relative humidity related to water activity?
Water activity= relative humidity/100
What is a facultative anaerobe?
A microbe that can grow with or without oxygen
What is a psychrotroph?
A microorganism that grows at 7 degrees Celsius or below (in the refrigerator)
What property does Aspergillus glaucus have that allows it to grow on dried fruit??
It is xerophillic.
What color are Staphylococcus aureus colonies on Baird Parker agar?
black
Why is egg yolk used in the media for the isolation of Bacillus cereus?
To check for the lecithinase reaction
What is the selective agent in the following medium: proteose peptone yeast extract, sodium chloride, sodium glycerolphosphate, maltose, lactose, sodium azide, bromcresol purple, agar, and water?
Sodium Azide
What does LAL stand for?
Limulus ameobocyte lysate
Which way does DNA replicate?
5’ to 3’
Most common pathogen found in outbreaks of cheese?
L. monocytogenes
Green bean canning pathogen ?
C. botulinum
What is the light absorbing pigment in plants?
Chlorophyll
Difference between fungi, algae, and other higher plant?
Photosynthesis
Difference between eukaryotic and prokaryotic?
Defined nucleus (eukaryotic), circular DNA (procariotic), mitocondria (eukariotic).
Time in minutes for one log reduction?
D-value
Name 5 organelles of cells:
Mitochondria, nucleus, vacuola, ribosome, golgi aparatus.
What is the difference between prebiotic and probiotic?
Probiotic is living microbials which promotes health; prebiotic is some indegestible food which promotes growth of microbials to promote health
Name two homofermenters?
Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus helviticus, Lactococcus fascum, Streptococcus thermophilus
Name two heterofermenters?
Lb. casei, Bifidobacterium breve. Lb. fermentum ,Bacillus infantis, Lb. fermentum , Lb. plantarum ,Bacillus longum
Vitamin C is sometimes added to frankfurters, why?
To enhance the rate of cured color formation in the frankfurter It sounds good to have Vitamin C on the label
Why is summer sausage shelf-stable?
pH is near the isoelectric point of myosin and actin
what is the maximum % of fat that you can legally have in a cooked sausage product?
30%
what is proteose peptone?
is an enzymatic digestion of animal tissues. commonly used in the prep of culture media for the production of toxins, and in the fermentation industry for starter cultures. It is a highly nutritious source for the growth of a wide range of microorganisms
if the total plate count is 500 CFU/ml, with the generation time of 30 min., what will the total plate count be after 3 hours?
32,000 CFU/ml
what is the color of typical Salmonella colony on EMB agar?
colorless
in the US, what is the maximum amount of fat allowed in frankfurters?
30%
in the US, what is the maximum amount of combination of fat and water allowed in frankfurters?
40%
According to the federal regulations, what food product open dating terms is required for frankfurter packages? A.sell by, B.use by, C.best if used by, or D.none of the above
none is required. product dating is voluntary and not required by federal regulations
Arrange these foodborne pathogens in the increasing order of their approximate onset time of symptoms due to infection or intoxication: Listeria monocytogenes, Staphylococcus aureus, Clostridium perfringens, and Vibrio cholerae
Staphylococcus aureus (2-4hr) Clostridium perfringens (6-12hrs) Vibrio cholerae (18-36hrs) Listeria monocytogenes (1-30 days or more)
in predictive food micro, growth rate is calculated by linear or non-linear regression on “log of counts vs. time plot”. which model cannot be used for calculating growth rate: A.logistic model, B. Arrhenius model, C.Gompertz model, D.baranyi model?
Arrhenius model
A food sample was analyzed for aerobic plate count by diluting 100 and 1,000 times separately. the # of colonies on plate w/1:100 dilution was 240 with 1:1,000 was 35. What is the exact aerobic plate count of the food sample?
(240+35) X 100/(1X1 + 0.1X1)= 25,000 CFU/ml
pathogens that are responsible for more than 75% of human deaths caused by known pathogens in the US
Salmonella, Listeria, and Toxoplasma. Followed by norwalk-like viruses, campylobacter, and E. coli O157:H7
Name the foodborne pathogen that has the highest mortality rate
Vibrio vulnificus (50% fatality rate)
of the following pathogens, which one was recognized even 30 years ago: campylobacter jejuni, Listeria monocytogenes, Bacillus cereus, Cyclospora cayetanensis?
Bacillus cereus
What do the Grashof number, Nusselt number, Prandtl number, Biot number, and Fourier number all have in common?
they are all dimensionless
prior to refrigeration, what was the primary method used for food preservation?
Fermentation
name 4 of the 6 primary classes of pathogenic E. coli that cause diarrhea
Diffuse-adhering (DAEC), enteropathogenic (EPEC),enterotoxigenic (ETEC),Enteroinvasive (EIEC),Enterohemorrhagic (EHEC),Enteroaggregative (EAEC)
what is the genus and species of the Thompson seedless grape?
Vitus vinifera
which fungus is responsible for producting the etiologic agents of aflatoxicosis?
Aspergillus flavus
what is the difference between the envelopes (everything outside the plasma membrane) of gram positive and gram negative cells?
Gram positive cells have a single thick peptidoglycan or murein layer, while gram negative cells have a thin peptidoglycan layer surrounded by an outer membrane
many fungi are dimorphic. what does dimorphic mean?
they can change from a yeast form to a mold form
aflatoxin can be detected by placing material under: A.fluorescent light, B.a light bulb, C.UV light, or D. infared light?
C. UV light
the fungus Claviceps purpurea produces a group of toxins that cause: A. turkey X disease, B. ATA, C. diarrhea and vomiting, or D. ergotism
D. ergotism
aflatoxins are NOT produced by: A.Aspergillus flavus, B. Aspergillus parasiticus, or C.Aspergillus chraceus
C.Aspergillus chraceus
the consumption of rotten apples may lead to intoxication by the presence of: A.yeast, B.spoilage bacteria, C.aflatoxins,or D.patulin
D. patulin
the critical events of infection by ingested virus appear to occur in: A.esophagus, B.stomach, C.small intestine, or D. large intestine
C.small intestine
what is the process of adding sugar to wine making?
Chaptalization
what is the difference between regular beer and light beer?
light beer averages 33% less calories than regular beer
in the brewing industry, what is “pitching”?
addition of yeast to the cooled wort
the presence of mold Botrytis cinerea in wine can create a problem in: A.fermentation, B.crushing, C.filtration, or D.aging
C. filtration: it produces B-glucans, which are large polymers that clog filters
What is the cause of the haze in beer?
incomplete protein hydrolysis during mashing or insufficient protease activity
what does the acronym NARMS stand for?
National Antimicrobial Resistance Monitoring System
define a fortified wine and give an example
When distilled alcohol is added to wine to increase the alcohol content; port, sherry, madeira, marsala, Commandaria wine and vermouth.
what variety of grape is used for fume blanc wine?
Sauvignon Blanc
what is a terrior in the winemaking industry?
the soil
How did cheese-makers overcome the kosher problem of rennet?
its produced from a microbiological source as chymosin
How is CO2 produced in traditional champagne manufacture?
additional sugar (24g/L) is added prior to bottling, whereafter yeast participate in a 2nd fermentation to produce CO2
what is the main difference in the manufacturing steps between red and white wine production?
red wine is fermented w/ the grape skins on
which media may be used to selectively enumerate coliforms?
Violet Red Bile Agar (VRBA)
what are the selective agents of VRBA?
bile salts and crystal violet
what do Z-values represent for a microbial population?
The temp required to change a D-value by one log (D is a decimal reduction time at a specific temperature)
in a recent outbreak of foodborne illness in RTE meats by Bil Mar Foods resulted in a recall of 76 million pounds of product. Name the causitive agent and rare strain that was found in these products.
Listeria monocytogenes type E
list 5 genera of bacteria and molds that produce antimicrobial agents
Penicillium ,L. lactis, Lactobacillus, Pediococcus,Streptomyces
name 4 bacteriocins produced by lactic acid bacteria and state the most thoroughly studied
Nicin, pediocin, diplocoxin, helveticin, and lactacin (nicin most thoroughly studied)
give the genus and species of one microorganism for each of the following categories: gram negative, strict anaerobe, foodborne pathogen, sulfide spoiler
gram negative= Salmonella typhimerium or E. coli;strict anaerobe= C. botulinum;foodborne pathogen= S. aureus, Listeria monocytogenes Sulfide spoiler= Desulfotomaculum nigrificans
give the genus and species for which the following media are selective:TSC, MacConkey, McBride, Hektoen enteric
TSC= C. perfringens;MacConkey= E. coli;McBride= Listeria monocytogenes;Hektoen enteric=Salmonella enteriditis
Name the microorganism associated w/ the following: Ergot poisoning, Zearalenones in corn, Patulin, Aflatoxin
Ergot poisoning= Claviceps purpurea; Zearalenones in corn= Fusarium graminarium; Patulin= Penicillium eseparsum; Aflatoxin= Aspergillus flavus
what cheese is associated w/ the following major microorganisms: lactococcus, propionibacterium shermanii, penicillium roqueforti, Lactic streptococci
Lactococcus= cheddar (or mozzarella);propionibacterium shermanii= Swiss;penicillium roqueforti= Blue;Lactic streptococci= Edam, Gouda
name 5 microorganisms that have been associated w/food poisoning outbreaks
C. botulinum, C. perfringens, B. cereus, S. aureus, Salmonella, Shigella, Vibrio parahaemolyticus, E. coli, Listeria monocytogenes
what agency regulates the production, labeling, and sale of the following products: wine coolers, Emu, Turkey, Lite Beer
wine coolers= FDA; Emu= FDA; Turkey= USDA Lite Beer= Alcohol and Tobacco Tax and Trade Bureau (TTB)
what 2 microorganisms are the principal acid producers in the manufacture of sour cream?
Lactococcus lactis spp cremoris and Lactococcus lactis ssp lactis
name 4 water-soluble vitamins
B1 (thiamin), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), B12, B5(pantothenic acid), Folic Acid, vitamin C
what microorganism is used in the fermentation of both bread and beer?
Saccharomyces cerevisiae
a microbial population of 3,000 CFU/ml that is exposed to a 2D process will theoretically have a final population of what?
30 CFU/ml
