Food Microbiology Exam queries and
answers graded A+
Microbiological Criteria - ANS✅✅-used to assess the safety, quality, adherence to good
manufacturing practices (GMPs), and suitability of a food or ingredient for a particular purpose or
target population
Standard - ANS✅✅A microbiological criterion that is part of law, ordinance or regulation
Example of a Standard - ANS✅✅USDA performance standards for salmonella in poultry
Suitability - ANS✅✅Pass or fail of food quality
Guideline - ANS✅✅A microbiological criterion used by the food industry and regulatory agency to
monitor a manufacturing process (looking at environmental processes)
You should treat a guideline like a standard though
Guideline example - ANS✅✅Control of LM and other post-process contaminants
Specification - ANS✅✅A microbial criterion that is used as a purchase requirement between a
buyer and a vendor
(this is more of a contract, so what levels can the pathogens be at and what pathogens are
important to test for)
Why sample at all? - ANS✅✅-Things will go incorrectly
-Can pick up those mistakes
-Verification checks
A microbiological criterion should include.... - ANS✅✅-Idenity of food or ingredient
-Identity of contaminant of concern
-Analytical method for detection or quantification of each contaminant
-Sampling plan
,-Microbiological limits considered appropriate to the food
Index organisms - ANS✅✅-Organisms that signal the possible presence of pathogenic or toxigenic
organisms within a sample (more specific)
-Listeria genus, Coagulase positive Staph, generic E coli
Indicator organisms - ANS✅✅Organisms that reflect general bacteriological quality or safety of a
sample
-Examples include total aerobic plate count, coliform, yeasts, molds, indicator organisms
Ideal Indicator or product safety - ANS✅✅-Easily and rapidly detectable
-Easily distinguishable from other food flora
-Consistent association with the pathogen whose presence it is to indicate
-Growth and survival should equal those of pathogen
-Present when pathogen of concern is present
-Absent in food free of pathogen
-Specificity to intestinal tract may be desired (where does the pathogen reside)
-May occur in high numbers in feces
Coliform example - ANS✅✅-Common in quality testing for dairy
-Gram negative, non spore forming rods that ferment lactose to acid within 48 hours
-E coli fits that description
-Coliforms comprised primarily by 5 genera of the family of Enterobacteriaceae
-This includes so many organisms it would be an indicator organism
Is coliform testing an adequate indicator of product safety? - ANS✅✅-Different numbers of
coliform allowed in a product to still be considered quality and safe
What is not included in coliform testing? - ANS✅✅Need to account for where the organisms
reservoirs are and others
-For example, mushrooms are grown in the soil and will have a much higher number of coliform
, Fecal Coliform example (Product Safety) - ANS✅✅-These are coliform that produce acid and gas in
EC growth at 45C (super specific)
-Primarily found in E coli but some others fit this definition
-Viruses can also be in fecal coliform
Indicators of Product Quality - ANS✅✅-Usually specific
-Growth of a specific organisms results in spoilage of product (yeast, mold, lactic acid, total plate
count, osmophilic yeast)
-Total microbial counts are used but they have greater value as indicators of the existing state of a
given product that as predictors of shelf life (this is looking at time zero)
3 Organisms associated with product quality and their food - ANS✅✅-Acetobacter and Cider
-Bacillus and Bread Dough
-Yeast and fruit juice
What determines the microorganisms of concern and testing required? - ANS✅✅-Experience of
manufacturer and supplier
-Supplier expectations (Whats been done before, R and D)
-Unfortunate circumstances (what pathogens have been present before)
-Government suggestions
-Microbiological consultants
Microbiological Sampling of Foods - ANS✅✅Purpose is to identify production lots within a level of
confidence. That are inferior or unsafe
Production lot - ANS✅✅Quantity of food produced, handled, and stored within a limited time
period under uniform conditions
-If there is no established break in production then you do not know when the actual issues started
Sampling Plans and Risks - ANS✅✅-Plan is designed by balancing the level of risk the vendor is
willing to accept relative to himself or the consumer
-Balance safety and economic factors (true pathogens should not be influenced by money)
-Balance between quality and economic factors
answers graded A+
Microbiological Criteria - ANS✅✅-used to assess the safety, quality, adherence to good
manufacturing practices (GMPs), and suitability of a food or ingredient for a particular purpose or
target population
Standard - ANS✅✅A microbiological criterion that is part of law, ordinance or regulation
Example of a Standard - ANS✅✅USDA performance standards for salmonella in poultry
Suitability - ANS✅✅Pass or fail of food quality
Guideline - ANS✅✅A microbiological criterion used by the food industry and regulatory agency to
monitor a manufacturing process (looking at environmental processes)
You should treat a guideline like a standard though
Guideline example - ANS✅✅Control of LM and other post-process contaminants
Specification - ANS✅✅A microbial criterion that is used as a purchase requirement between a
buyer and a vendor
(this is more of a contract, so what levels can the pathogens be at and what pathogens are
important to test for)
Why sample at all? - ANS✅✅-Things will go incorrectly
-Can pick up those mistakes
-Verification checks
A microbiological criterion should include.... - ANS✅✅-Idenity of food or ingredient
-Identity of contaminant of concern
-Analytical method for detection or quantification of each contaminant
-Sampling plan
,-Microbiological limits considered appropriate to the food
Index organisms - ANS✅✅-Organisms that signal the possible presence of pathogenic or toxigenic
organisms within a sample (more specific)
-Listeria genus, Coagulase positive Staph, generic E coli
Indicator organisms - ANS✅✅Organisms that reflect general bacteriological quality or safety of a
sample
-Examples include total aerobic plate count, coliform, yeasts, molds, indicator organisms
Ideal Indicator or product safety - ANS✅✅-Easily and rapidly detectable
-Easily distinguishable from other food flora
-Consistent association with the pathogen whose presence it is to indicate
-Growth and survival should equal those of pathogen
-Present when pathogen of concern is present
-Absent in food free of pathogen
-Specificity to intestinal tract may be desired (where does the pathogen reside)
-May occur in high numbers in feces
Coliform example - ANS✅✅-Common in quality testing for dairy
-Gram negative, non spore forming rods that ferment lactose to acid within 48 hours
-E coli fits that description
-Coliforms comprised primarily by 5 genera of the family of Enterobacteriaceae
-This includes so many organisms it would be an indicator organism
Is coliform testing an adequate indicator of product safety? - ANS✅✅-Different numbers of
coliform allowed in a product to still be considered quality and safe
What is not included in coliform testing? - ANS✅✅Need to account for where the organisms
reservoirs are and others
-For example, mushrooms are grown in the soil and will have a much higher number of coliform
, Fecal Coliform example (Product Safety) - ANS✅✅-These are coliform that produce acid and gas in
EC growth at 45C (super specific)
-Primarily found in E coli but some others fit this definition
-Viruses can also be in fecal coliform
Indicators of Product Quality - ANS✅✅-Usually specific
-Growth of a specific organisms results in spoilage of product (yeast, mold, lactic acid, total plate
count, osmophilic yeast)
-Total microbial counts are used but they have greater value as indicators of the existing state of a
given product that as predictors of shelf life (this is looking at time zero)
3 Organisms associated with product quality and their food - ANS✅✅-Acetobacter and Cider
-Bacillus and Bread Dough
-Yeast and fruit juice
What determines the microorganisms of concern and testing required? - ANS✅✅-Experience of
manufacturer and supplier
-Supplier expectations (Whats been done before, R and D)
-Unfortunate circumstances (what pathogens have been present before)
-Government suggestions
-Microbiological consultants
Microbiological Sampling of Foods - ANS✅✅Purpose is to identify production lots within a level of
confidence. That are inferior or unsafe
Production lot - ANS✅✅Quantity of food produced, handled, and stored within a limited time
period under uniform conditions
-If there is no established break in production then you do not know when the actual issues started
Sampling Plans and Risks - ANS✅✅-Plan is designed by balancing the level of risk the vendor is
willing to accept relative to himself or the consumer
-Balance safety and economic factors (true pathogens should not be influenced by money)
-Balance between quality and economic factors
