NU FS 363 Midterm 1
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. What would you like to do?
What does TOTE stand for
Take out to eat foods
Why is the consumer important in the food supply
Demands new foods and convenience foods
Market is often driven by consumer opinions, whether they are correct or not (assumptions of health benefits and negatives - food irradiation greatly reduces risk of foodborne disease, but consumers oppose it because they assume food will be radioactive)
genetically modified organisms
What are the hazards in the food supply (6)
- Nutritional concerns
- Environmental contamination
- Natural toxins
- Pesticide residues
- food additives
What are three government agencies that regulate the food supply? USA?
- Health Canada
- -Food and Drug Act Regulations
- Canadian Food Inspection Agency (CFIA)
- -Food inspection
- Agriculture and Agri-Food Canada
- -Standards for agricultural products
- -FDA, FSIS, USDA
Sum the history of food preservation (product and year)
- Beer production
- -7000 BC
- Wine fermentation
- -3500 BC
- Salting and drying
- -3000 BC
- -1000 BC
Who invented canning? What year?
Nicholas Appert in 1810
What was Pasteurs contribution
He found that bacteria sours milk (1857)
Heat destroys bacteria in wine and beer (1860)
What was Koch's contribution to food microbiology?
- Links bacteria and disease (1876)
- -Koch's postulates
What was Lister's contribution to food microbiology?
- Lactic acid bacteria ferment milk and the concept of aseptic technique/antiseptic
Who discovered E. Coli? What year?
Theodor Escherich in 1885
When was the first commercial facility for irradiation of food around
In what year were foodborne pathogens recognized
1975 to present
Correctly write salmonella
Salmonella enterica serovar Typhimurium
Genera species subspecies then type or serovar
Correctly write e coli
Escherichia coli 0157:H7
What are microorganisms found in foods (5)
What are sources of contamination of food (7)
- Animal Feed
- Intestinal tract of humans and animals
- -meat, vegetable or water contamination
- Human human
- utensils (cross contamination)
- Air, dust
What is a bacteria that can be found in vacuum packaged hot dogs
What is the term for bacteria associated with food
What is a Chemoheterotroph?
- A bacteria associated with food
- Use organic compounds as a source of energy
What do bacteria need for growth (9)
- Carbohydrates (glucose)
- Nitrogen source (amino acids, ammonia, nitrite)
- Trace elements
What is likely to limit growth of bacteria
pH, available water.
Growth is unlikely to be limited by nutrient composition of food.
Why is packaging important in extending storage life?
It has a modified atmosphere.
What are the four phases of the microbial growth curve, and what are the two axis?
- Lag phase
- Exponential growth phase
- Stationary phase
What does growth rate help microbiologists determine?
- How fast a food might spoil
- how fast a food ferments
What are a couple of important parameters that food microbiologists use for bacteria to determine food spoilage
- Generation time
- Growth rate
What is the generation time
- It is the time required for a population bacteria to double
- It is a reflection of how fast a culture will grow useful for comparative purposes
What is the equation for generation time
- GT = (T x 0.301)/(log Nt - log N0)
- 0.301 = log of 2 for doublings
What is the equation to find the number of generations in a bacterial population
n=T/GT (time over generation time)
What is the first thing someone should do when culturing bacteria
- Call your mum
- tell her about the yeast infection
- Gram stain
What are the possible results of a gram stain? Explain why there are differences and what it means?
- A gram positive bacteria will stain purple. They have no outer wall but a thick layer of peptidoglycan.
- Gran negative bacteria stain pink. They have an outer cell wall and a thin layer of peptidoglycan
What are the 5 steps of the gram stain procedure
- 1. Gently heat fix culture smear by passing slide through flame
- 2. Flood slide with crystal violet for 1 min. Wash slide gently. (all cells purple)
- 3.Flood slides with iodine solution for 3 mins (all cells still purple)
- 4. Decolorize slide with alcohol for 30 seconds (gram neg cells will lose purple colour)
- 5. Counterstain with safranin for 1-2 mins (gram positive will be purple)
Describe a yeast
Nonfilamentous, unicellular fungi
How do yeast reproduce
- Sexual through binary fision
- asexual reproduction through budding
- Grow over a range of temperature and moisture.
- Exhibit septate hyphae
- Sporulating and spread by air currents
What type of yeast is important for food spoilage? What else is it important in
- key for brewing and baking
What are molds most likely to cause disease in
Cheese and other fermented products
How do molds cause disease in humans
What foods to viruses grow in
They do not grow in food
What viruses can be transmitted through foods
Hepatitis A and norovirus
What foods to parasites grow in
They do not grow in foods
What do parasites need to grow
Name a common parasite from flesh-eating animals
How are parasites controlled
- Cook meat to above 65 degrees celcius.
- -Internal temp of 70 gives safety margin
Some cysts destroyed by freezing
How do protozoa survive outside of a host
Cysys and oocysts
Name an example of protozoa
- Entamoeba histolytica
- Giardia lamblia
- Cryptosporidium parvum
What does food spoilage relate to?
Describe the food spoilage of different food compositions.
- Lipids = rancidity
- * oxidative (peroxides etc.) chemical
- * Hydrolytic (free fatty acids) microbial
- Proteins = proteolysis (microbial)
- *putrefaction = ammonia, H2S amines
- Carbohydrates = fermentation (microbial)
- *organic acids = souring
How does raw meat spoil?
Protein degradation if stored in oxygen
how does bread spoil?
How does oil spoil?
- Rancidity due to oxidation
- NOT MICROBIAL
How does yogurt spoil?
Production of too much acid; mold growth
What is the term for a food with a shelf life
what is the storage life of perishable foods
What has to be on the packaging of packaged foods? retail foods?
- a.) BBD
- b.) Packaged on date
What does a best before date indicate
How long the product will maintain its quality for.
What percentage of foodborne disease incidents are reported?
Less than 10%
What are two mechanisms of foodborne illness. Describe the mechanisms
- -toxin produced in the food is ingested and causes illness
- -organism is consumed and colonizes GI tract and subsequently causes illness.
Name four organisms involved in intoxication and foodborne illness. (one is a mold)
- Bacillus cereus
- Clostridium botulinum
- Staphylococcus aureus
- Aspergillus flavus (mold)
Name five types of microbes that cause foodborne illness through infection
- Campylobacter jejuni
- Enteropathogenic Escherichia coliEnterohemorrhagic Escherichia coli
- Listeria monocytogenes
- Salmonella species
What percentage of the food market is composed of fermented foods. Provide examples
- Lactic fermentations (cheese, meat, pickles, wine, yogurt)
- Yeast fermentations (beer, bread, wine)
- Mold fermentations (cheese, meat, soy)
What the term used to describe production of gas in a vacuum pack.
Blown pack spoilage
What could cause blown pack spoilage in fresh meat
- Gas producer
- *Carb content very low
- *Not usually metabolized to produce gas
- Strict anaerobe
- Psychrophile (optimum growth temperature under 20 because of refrigeration)
- Doesn't grow well in presence of other organisms (other organisms very low according to plate count)
- Survives antimicrobial treatments used in meat processing
What class of bacteria will grow in a sandwich product and cause blown pack spoilage? why?
(assuming no odor)
- Lactic acid bacteria
- Cheese, meat in sandwich. Not protein because no odor.
- Environment is low oxygen and high carbs.
- Some LAB will produce gas from carbs
What does total cell count tell us about a product? What doesn't it show?
- It directly counts cells and is viable
- It can indicate spoilage, by sheer number but does not indicate food safety.
- Gives cell numbers but not diversity.
- Changes in number in the processing plant can indicate something has gone wrong.
What do we grow cells in for a plate count
Plate count agar (PCA)
What class of bacteria can grow in a high 02 environment
- Gram positive bacteria
- Gram negative bacteria cant grow
What do lactic acid bacteria like to use for food?
Sucrose because it is very fermentable
What is the standard incubation temperature of total plate count agar?
Describe Pour plating
Take one ml of sample into bottom of petri dish. Add sterile medium and mix gently but well.
Describe spread plate
0.1 ml of sample on surface of prepoured agar plate. Spread sample evenly over surface.
What do you need to do with a solid sample to plate it?
Blend it with a diluent
Describe the two diluent types
- Blender: need to sterilize bag and reuse,
- Stomacher: can dispose of the bag after
What are advantages and disadvantages of the pour plate
- Advantage: Don't have to have media pre-prepared
- Disadvantage: Have to have molten media (45 degrees). Refrigerated organisms have a low yield.
What are advantages and disadvantages of spread plates?
- Advantage: can buy them. Cool enough so they do not kill organisms.
- Disadvantage: expensive
Describe serial dilutions
always done in 1:10 intervals. Take 1ml of sample and 9ml of diluent.
What is the minimum number of cells required for accuracy
What is selective media
Selects for one type of bacteria.
Describe the difference between plating and enrichment
- Plating=estimate number of cells/g or mL of food.
- Enrichment = selective broth
- *allows growth of specific organism
- *presence or absence only (does not give number)
- *often used for detection of pathogens
What type of plating is commonly used for detection of pathogens
What does the epidemiology of foodborne disease attempt to do
- Identify cause
- Determine mode of transmission
- Evaluate method of control
What is the sequence of events for foodborne disease
- Organism must contaminate food
- One of the following must happen:
- - Organism or toxin must survive storage and processing
- -Organism allowed to multiply (maybe)
- Sufficient quantities contaminated food eaten
Which foodborne pathogens have decreased since 1989? Which one has increased? Why?
- Salmonella spp.
- Staphylococcus aureus
- Clostridium perfringens
In 2006 Campylobacter jejuni
was starting to be regulated and appeared to increase because it was being reported.
What are important causes of foodborne illness in Canada (11)
- Staphylococcus aureus
- Clostridium perfringens
- Campylobacter jejuniNorovirus
- Bacillus cereus
- Escherichia coli
- Yersinia enterocolitica
- Clostridium botulinum
- Listeria monocytogenes
- Vibrio parahaemolyticus
What is the food category that is the most responsible for foodborne disease
What is HACCP
Hazard Analysis Critical Control Point
What is CFIA
Canadian Food Inspection Agency
What is FSEP
Food Safety Enhancement Program
What is CCP
Critical Control Point
What is GMP
Good Manufacturing Practices
What is SOP
Standard Operating Practices
What is FDA
- Food and Drugs Act (Canada)
- Food and Drug Administration (US)
What are the benefits of implementing HACCP
- Maximize product safety
- *Identifies hazards - eliminate or control to an acceptable level
- Improve product quality
- *by-product of improved controls and consistency
- Improve operational efficiency, profitability
- *Standard procedure, record keeping control over product
- Increased customer confidence/demand
- *Increased awareness of food recalls.
- Market access/international trade and equivalence
- *same 7 principles apply to differing systems
- Legal liability
- *useful in defense of due diligence
At what government level is HACCP granted at? By who?
Federal level by CFIA
What is the ISO 9000 quality system
A quality management system aimed primarily at preventing any non conforming product during production and distribution
- Write what you do
- Do what you write
- prove it
- (improve it if necessary)
Identifies specific hazards and installs preventative measures
A science based systematic, preventative approach to controlling food safety that targets resources to critical areas of the process.
What is the purpose of FSEP
The Food Safety Enhancement Program was developed to assist processing plants with the development and implementation of the HACCP System.
What are the prerequisite programs for HACCP (7)
- All of the following 7 practices/procedures are carried to favor the production of safe food but focus on environment
- Transportation, purchasing, receiving, shipping and storage
- Sanitation and pest control
- Allergen control
What is the difference between a prerequisite program and HACCP
Prerequisite program focuses on the environment while HACCP is about the food product.
What are samples placed in for dilutions
0.1% sterile peptone water
Describe the premises prerequisite program
- Building exterior
- *Outside property and building maintained
- Building interior
- *Design, construction and maintenance
- *Lighting, ventilation, waste disposal, inedible areas
- Sanitary facilities
- *Employee facilities
- *Equipment cleaning and sanitizing facilities
- Water quality and supply
- *Water re-circulation
- *back-flow control
- *must be potable
Describe the transportation, purchasing/receiving/shipping and storage prerequisite system
- Purchasing/Receiving/Shipping and Storage
Describe the equipment prerequisite program
- General equipment
- *Design and installation
- *Maintenance and calibration
Describe the personnel prerequisite program
- General food hygiene program
Describe the sanitation and pest control prerequisite program
- Sanitation program
- *water temperature requirements, chemical concentrations to be used, verification program, procedures and frequencies for cleaning and sanitizing
- Pest control
- *written program, pesticide usage log, service reports, corrective actions, verifications
Describe the Recall system of the perquisite program
- Recall Plan
- Product coding and labeling
Describe the allergen control of the prerequisite program
Allergen control program
What must occur with prerequisite programs
- They must be monitored
- *Who, what are they doing, how often, how do they do it, standard to be met and records must be kept.
- Deviation procedures must be outlined.
What are the three questions HACCP answers
- What are the hazards associated with my product?
- Where do these hazards occur?
- How can I control or eliminate these to an acceptable level?
What are the 7 principles of HACCP
- Conduct a hazard analysis
- Determine critical control points
- Establish critical limits
- Establish monitoring procedures
- Establish deviation procedures
- Establish verification procedures
- Establish record keeping (for points 1-6)
What are the 12 steps to developing a HACCP plan
- 1. Assemble your HACCP team
- 2. Describe your product and identify its intended use (Form 1)
- 3. List product ingredients and incoming material.
- 4. Construct a process flow diagram and a plant schematic (Forms 3 and 4)
- 5. Verify, on site, your process flow diagram and plan schematic
- 6. List the hazards associated with each step and incoming material in your plant's process (principle 1)
- 7. Apply the HACCP decision tree to determine CCPs (Principle 2)
- 8. Establish critical limits (Principle 3)
- 9. Establish monitoring procedures (Principle 4)
- 10. Establish deviation procedures (Principle 5)
- 11. Establish verification procedures (Principle 6)
- 12. Establish record keeping and documentation procedures for principles 1 through 6 (Principle 7)
Describe form 1
- Step 2 of the HACCP plan
- Describes product and identifies its intended use
- Product name, important characteristics, how the product will be used, packaging, shelf life, where it will be sold, labeling instructions, special distribution control
Describe form 2
Lists product ingredients
Describe form 3
- Process flow diagram
- - Includes steps from receiving to final shipping
- - Product specific
Describe form 4
- Plant schematic
- Shows product flow and employee traffic flow
What is hazard analysis?
- It is an essential part of HACCP
- Every ingredient and step of a process is analyzed to determine what hazards are present
- The hazards are controlled, reduced or eliminated
What are the classes of food safety hazards (3)
- *bacterial pathogen
- *Natural toxins
- *Foreign Object
Describe form 8
- Associated with principle 2 of HACCP (step 7).
- Determines critical control points
What are the three most common critical control points?
Cooking, chilling or refrigeration and formulation control
What are the differences between prerequisite and CCP. What about process control?
- Prerequisite: Indirectly deal with food safety issues, More general - not product specific and non-compliance rarely results in action against the product
- CCP: Directly deals with food safety issues, product specific and non-compliance results in action against product
- Process control: An activity that enhances the ability of a CCP to be effective, must be linked to a specific hazard and CCP, often used in slaughter.
What is a critical limit
- It is one or more prescribed tolerances that must be met to ensure that a CCP effectively controls a hazard.
- The limits may meet government regulations or company standards.
Describe Form 10
establishes critical limits and is associated with principle 3 and step 8 of the HACCP protocol.
What is monitoring
A planned sequence of observations or measurements of critical limits designed to produce and accurate record and is intended to ensure that the critical limit maintains product safety.
Describe Form 10
establishes monitoring procedures, deviation procedures, verification procedures and record keeping. It is associated with principles 4-7 and steps 9-12 of HACCP
What is deviation
Failure to meet the required critical limits defined for a CCP
What is verification
Methods, procedures and tests used to determine if the HACCP system is valid and operating properly
Describe records of HACCP
in-plant documentation that is kept for each CCP required to ensure that the HACCP plan is followed.
Describe form 11
- It is the new step for FSEP program - process controls
- Multiple steps help reduce the single hazard Always linked to subsequent CCP
- Must be validated by processor to demonstrate that PC is effective in reducing hazards
- Monitoring, deviation procedures and verification procedures must be in place for PC
What are extrinsic factors
- Factors that can be controlled
- Factors in the environment external to the food, which affect both the microorganisms and the food itself during processing and storage
- 1. Temperature
- 2. Gaseous environment
What is the single most important factor to control the rate of growth of microorganisms
What are important concepts to consider regarding temperature as an extrinsic factor
- Minimum growth temperature
- Optimum growth temperature
- Maximum growth temperature
What is the chemistry kinetics rule of thumb
The reaction rate doubles with every 10 degree temperature increase (until it reaches a limit when protein degradation occurs)
What type of testing should not be used for food and why
Microbial testing because it takes too long
Why is minimum growth temperature important
Because it is important in determining growth location
What is the danger zone and why is it important
- It is a key concept in food spoilage and safety.
- It is from 4.4 degrees to 60 degrees. Growth of pathogens have been selected to grow at body temperature. Any food exposed to the danger zone for two hours it at risk.
- Spoilage of food will occur if exposed to the danger zone
What is a Psychrophile
An organism that grows at temperatures of 20 degrees or less. Not common in food except in some fish.
Provide an example of a Psychrophile that may be common in food
What is a Psychrotroph
An organism with its optimum at around 30 degrees. Grows at refrigeration temperatures, optimum growth of 20 degrees.
What is a mesophile
An organism with an optimum temperature of 35 degrees or higher. Minimum growth of 7 to 10, and max growth of 40-60.
What is a psychrotroph that is common in food
what is a mesophile that is common in food
Escherichia Coli and Staphylococcus aureus
What is a thermodurics
An endospore forming bacteria that survive but do not grow at temperatures over 60. Pretty much the same as Mesophiles, but have endospores.
What is a thermoduric that is common in food
Bacillus spp. and Clostridium spp.
What is a thermophile
An organism that grows at temperatures above 45 (optimum). Not common in foods, but some organisms grow and high temperatures.
What is a thermophile that is common in food.
Thermophiles are not common in food. Streptococcus thermophilus may be apparent because of boiling of soup.
Describe the temperature chart of bacteria
- 121 degrees - destruction of bacterial endospores
- above 100- all cells killed, only achieved with pressure/temp combinations
- above 80 - vegetative cells killed
- 60-4.4 danger zone (active growth)
- Below -20 destruction of some parasites
At what temperature does death of viable cells occur
Death of viable cells starts to occur after 60 degrees
What temperature should hot foods be stored at
Above 60 degrees
What temperature should cold foods be stored at
Below 4 degrees
Name three pathogens that grow under 4
- Clostridium botulinum
- Yersinia enterocolitica
What is a difference between bacterial spores and fungal spores
ndospores are resistant to heat, drying and disinfecting chemicals
Fungal spores are not heat resistant
Why is the gaseous environment important in terms of extrinsic factor for microbial growth
Primarily comparing difference between aerobic and anaerobic storage
Describe aerobic storage and types of bacteria that grow
- Primarily gram-negative, non-sporeforming, rods (pseudomonads)
- Oxidative and breakdown fats and proteins = odors
At what concentration of CFU are odors detectable in aerobic storage in meat. Why is there an odor?
Oxidative and breakdown fats and proteins. Odors are detectable at 10^6 to 10^7 CFU/g of meat.
Describe anaerobic storage in terms of extrinsic factors.
- Usually with carbon dioxide
- Modified atmosphere or vacuum packed
- Usual bacteria are gram-positive lactic acid bacteria. Fermentative and convert sugars to lactic and acetic acid
What is a key difference between the detection of spoilage in aerobic and anaerobic bacteria?
- Aerobic bacteria produce odors because of oxidation and breakdown of fats and proteins. This signifies spoilage
- Anaerobic bacteria ferment sugars to lactic and acetic acid. Spoilage is only detected after max population is reached.
What takes longer to spoil, anaerobic or aerobic bacteria?
Anaerobic bacteria because they do not produce an odour.
How can you preserve microbes
Freeze them to -80 and use glycogen stocks for preservation
What is the relationship between pressure and boiling point?
When pressure increases, the boiling point increases
What is Josh
A Whitneyphile <3
What determines the dominant population of a colony
It is related to the ideal population of bacteria and environmental conditions
What are the five intrinsic factors
- Physical structure
- Nutrients and natural inhibitor
- Water Activity
- Redox Potential
Describe the physical structure of intrinsic factors
- Idea that microbes reflect structure
- Physical barriers can prevent contamination of bacteria. (outside of meat and fruits)
- parasites can dig through the structure
Describe the nutrient and natural inhibitor of intrinsic factors
- Does the food have everything necessary for growth
- Are nutrients available microbially?
- Primary concept - how rich is the growth environment in terms of the nutrients
Enzymes produced by a microorganism influence its ability to utilize different energy sources.
What does fastidious mean
Bacteria require amino acids and or vitamins and growth factors
Name two types of natural inhibitors and how they work
- Lysozyme, found in egg whites, hydrolyses peptidoglycan
- Hops in beer produces humulones which is a strong antimicrobial preventing lactic acid bacteria from doing anything to the yeasr
Describe pH in terms of intrinsic factors
- Using pH as a control mechanism
- Usually acidic range
Recopy the intrinsic factor pH table
Go to lecture 8 notes
Why isn't food used stored at alkaline pH?
Breaks down food and effects food quality
Describe the succession of species in regards to pH
- Starts off neutral pH
- Streptococcus lactis uses nutrients early on and reaches stationairy phase. When it starts to die because of decreasing pH because of fermentation, Lactobacilli spp. begins to grow because they are not in competition. They drive the pH down, and then film yeasts oxidize the lactic acid and return pH to normal.
What is an indicator of osmotic strain
Describe water activity of intrinsic factors
Water activity is simply the ratio of the water vapor pressure in any kind of food system to the water vapor pressure of pure water
Why is water activity important
Water activity is used for compliance of government regulations, CFR, HACCP and other food safety programs.
Upper and lower level water activity measurements establish qualities for food products including: texture, microbial, flavor, appearance, aroma, cooking.
Know water activity chart
What is inhibited at water activity of 0.85
At what water activity can most pathogenic bacteria been inhibited at?
At what water activity are yeasts and molds stopped at?
What are three activities decrease water activity
What is osmotic dehydration
The moisture transfer process which occurs during the salting of fish or cheese etc. The food is surrounded by a solution with lower water activity.
high salt concentrations
High concentration of organ compounds (sugars)
Growth on dry foods
What is redox potential of intrinsic factors
- Oxidation - reductions basis for almost all biological reactions
- Growth reduces redox potential
What is the relationship between redox potential and growth
Growth reduces redox potential
What is an oxidizing agent? Reducing agent?
- Oxidizing agent accepts electrons
- Reducing agent donates electrons
What is Lestner's Hurdle concept
a bacteria might be able to overcome different challenges. if it can not overcome the challenge then it dies. Multiple challenges at the same time is more difficult to overcome.
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