Food Microbiology Exam quiz and
answers graded A+
Important things to consider in a risk assessment - ANS✅✅1. spore producers : Clostridium,
Bacillus, Fungi
2. Level of sterility : spoilage organisms can compete w/ pathogens in food.
who discovered fermentation - ANS✅✅Van Helmont
who identified the microscope - ANS✅✅Van Leeuwenhoek
Who established PCR using Thermus aquaticus enzyme - ANS✅✅Kary Mullis
Gilbert and Sanger determined what - ANS✅✅ways to recognize the specific base sequence of
DNA in 1977, called Sanger Sequencing.
HACCP - ANS✅✅Hazard Analysis Critical Control Points,
focuses on:
- knowing where problems with food safety might be and
- doing something to control/reduce likelihood of those problems.
biological hazards - ANS✅✅foodborne pathogens
- E. coli, Salmonella, L. monocytogenes, Campylobacter, Vibrio, Hep A, Norovirus, Clostridum
perfringins, C. botulinum, C. difficile. Prions, Cyclospora, Crypto, S. aureus, B. cereus, Toxoplasma,
Giardia
chemical hazards (added and natural) - ANS✅✅allergens:
- milk, eggs, fish, crustaceans, tree nuts, peanuts, wheat and soy
canada adds: mustard, shellfish
Europe adds: celery, mustard.
,added: medicines, food additives, pesticides, cleaners
natural: mycotoxin, allergens, mushrooms, heavy metals.
7 main HACCP principles - ANS✅✅1. hazard analysis
2. CCP
3. Limits for CCP
4. Monitoring limits for CCP
5. Corrective actions
6. Verification procedures to make sure HACCP is working as intended
7. record keeping procedures
BBQ chix hazard analysis (truck to processing belt) - ANS✅✅biological: salmonella, campylobacter,
l. mono, E.coli
chemical hazards: allergens (mustard, soy?)
physical: bone, metal
Examples of CCPs for biological, chemical and physical hazards - ANS✅✅bio: cooking, cooling, HPP,
formulation
chemical: labeling, cleaning
physical: metal detection, x-ray
CCP and cooling - ANS✅✅max temp limits: 130-80 no more than 1.5h, 80-40 no more than 5.
chilling: 90 mns post-cooking.
100ppm sodium nitrite increases the amount of time a product can have to cool (130-80 for 5h).
who is the food safety modernization act specific to? - ANS✅✅FDA
, static vs. cidal preservatives - ANS✅✅static: prevents microbial replication
cidal: kills microbes.
what size filtration do you need for protozoans? bacteria? viruses? chemicals? -
ANS✅✅protozoans: 0.1 um
bacteria: 0.01 um
viruses: 0.001 um
reverse osmosis: 0.0001 um
T/F organic acids can't be static and cidal - ANS✅✅F, what counts as growth and death is
ambiguous.
when the pH> pKa what is the form of the acid - ANS✅✅unprotonated conjugate base
-cannot enter cell, soluble in water
describe the action of AA decarboxylases - ANS✅✅pH buffers
- removes carboxyl group from AA, amines can now buffer.
Acid tolerance response, salmonella - ANS✅✅when pH drops, Salmonella makes acid shock
proteins to acidify its internal cellular environment.
when the pH< pKa what is the form of the acid - ANS✅✅protonated acid
- can enter cell, unsoluble in water.
parabens - ANS✅✅esterification of carboxyl group of benzoic acid
- undissociated form up to pH 8.5
- effective in pH range 3-8
- act against cytoplasmic membrane killing yeasts, molds and bact.
what preservative is found in wine and is effective below pH4 - ANS✅✅sulfites
answers graded A+
Important things to consider in a risk assessment - ANS✅✅1. spore producers : Clostridium,
Bacillus, Fungi
2. Level of sterility : spoilage organisms can compete w/ pathogens in food.
who discovered fermentation - ANS✅✅Van Helmont
who identified the microscope - ANS✅✅Van Leeuwenhoek
Who established PCR using Thermus aquaticus enzyme - ANS✅✅Kary Mullis
Gilbert and Sanger determined what - ANS✅✅ways to recognize the specific base sequence of
DNA in 1977, called Sanger Sequencing.
HACCP - ANS✅✅Hazard Analysis Critical Control Points,
focuses on:
- knowing where problems with food safety might be and
- doing something to control/reduce likelihood of those problems.
biological hazards - ANS✅✅foodborne pathogens
- E. coli, Salmonella, L. monocytogenes, Campylobacter, Vibrio, Hep A, Norovirus, Clostridum
perfringins, C. botulinum, C. difficile. Prions, Cyclospora, Crypto, S. aureus, B. cereus, Toxoplasma,
Giardia
chemical hazards (added and natural) - ANS✅✅allergens:
- milk, eggs, fish, crustaceans, tree nuts, peanuts, wheat and soy
canada adds: mustard, shellfish
Europe adds: celery, mustard.
,added: medicines, food additives, pesticides, cleaners
natural: mycotoxin, allergens, mushrooms, heavy metals.
7 main HACCP principles - ANS✅✅1. hazard analysis
2. CCP
3. Limits for CCP
4. Monitoring limits for CCP
5. Corrective actions
6. Verification procedures to make sure HACCP is working as intended
7. record keeping procedures
BBQ chix hazard analysis (truck to processing belt) - ANS✅✅biological: salmonella, campylobacter,
l. mono, E.coli
chemical hazards: allergens (mustard, soy?)
physical: bone, metal
Examples of CCPs for biological, chemical and physical hazards - ANS✅✅bio: cooking, cooling, HPP,
formulation
chemical: labeling, cleaning
physical: metal detection, x-ray
CCP and cooling - ANS✅✅max temp limits: 130-80 no more than 1.5h, 80-40 no more than 5.
chilling: 90 mns post-cooking.
100ppm sodium nitrite increases the amount of time a product can have to cool (130-80 for 5h).
who is the food safety modernization act specific to? - ANS✅✅FDA
, static vs. cidal preservatives - ANS✅✅static: prevents microbial replication
cidal: kills microbes.
what size filtration do you need for protozoans? bacteria? viruses? chemicals? -
ANS✅✅protozoans: 0.1 um
bacteria: 0.01 um
viruses: 0.001 um
reverse osmosis: 0.0001 um
T/F organic acids can't be static and cidal - ANS✅✅F, what counts as growth and death is
ambiguous.
when the pH> pKa what is the form of the acid - ANS✅✅unprotonated conjugate base
-cannot enter cell, soluble in water
describe the action of AA decarboxylases - ANS✅✅pH buffers
- removes carboxyl group from AA, amines can now buffer.
Acid tolerance response, salmonella - ANS✅✅when pH drops, Salmonella makes acid shock
proteins to acidify its internal cellular environment.
when the pH< pKa what is the form of the acid - ANS✅✅protonated acid
- can enter cell, unsoluble in water.
parabens - ANS✅✅esterification of carboxyl group of benzoic acid
- undissociated form up to pH 8.5
- effective in pH range 3-8
- act against cytoplasmic membrane killing yeasts, molds and bact.
what preservative is found in wine and is effective below pH4 - ANS✅✅sulfites
