Microbial Monitoring and Spoilage.

Question 1

1. How could microbial contamination be introduced in production chain?
2. What do microbes play a role in?

Answer 1

1. From raw product, equipment, environment, personnel.
2. Quality (shelf-life) safety of foods.

Question 2

1. Who enforce food legislation in the UK and who must follow it?
2. What does this legislation include in terms of microbes? – who developed this?

Answer 2

1. Food Standards Agency (FSA). – Followed by all those involved in meat production.
2. Microbiological Criteria for each particular type of food (e.g. meat). – developed by WHO, EU, International Commission on the Microbiological Specification for Foods (ICMSF), Codex Alimentarius Commission.

Question 3

How can microbiological criteria be put into practice?

Answer 3

Microbiological indicators used to determine whether a specific food lot is acceptable (safe) or not.
Used to indicate the required microbiological status of raw materials, ingredients and end-products at any stage of the food chain.
Criteria can be either mandatory or advisory and they fall into 2 categories:
- Standards: based on legal requirements and may result in reprocessing, rejection or destruction of a food lot.
- Specifications: Criteria used for contractual purposes by food businesses.

Question 4

1. Who introduced the Appropriate Level of Protection (ALOP) parameter?
2. What is the Food Safety Objective (FSO)?
3. What is the Performance Objective?

Answer 4

1. World Trade Organisation (WTO).
2. Maximum frequency and/or concentration of a microbiological hazard in a food AT THE TIME OF CONSUMPTION, designed to meet ALOP.
3. Maximum frequency and/or concentration of a hazard in a food at a specific step in the food chain before the time of consumption that provides or contributes to an FSO or ALOP.

Question 5

1. What is the Performance Criteria?

Answer 5

1. Effect on the frequency and/or conc. of a hazard in a food that must be achieved by the application of one or more control measures to provide or contribute to a PO or an FSO. E.g. refrigeration, addition of acid or other ingredients.

Question 6

1. Types of microbiological criteria in the meat industry.
2. For what meat stages do these criteria exist?

Answer 6

1. Food Safety Criteria – assess the safety of a product or a batch of foodstuffs.
   Process Hygiene Criteria – assess the hygiene of the production process.
2. Carcasses, minced meat, meat preparations and mechanically separated meat.

Question 7

1. Who sets the microbiological criteria for red met abattoirs?
2. What does the criteria detail and what is no longer a requirement?
3. What is also described by FSA?

Answer 7

1. Food Standards Agency (FSA).
2. Details the sampling of red meat carcasses.
   Surface sampling no longer a requirement.
3. Sampling frequency, sampling sites, method and target organisms.
   - Sampling frequency based on throughput and reduced with time if results satisfactory (check guidance). – Good for business as money saving.
   - Salmonella, APC, Enterobacteriacae.

Question 8

Methods of sampling red meat.

Answer 8

– Excision method.
Sterile cork borer (5cm squared) scores the surface tissue, removed using a sterile scalpel.
Only for determination of APC and Enterobacteriaceae.

– Sponge swap.

Question 9

1. Sampling frequency?
2. Sample method?
3. When to sample.

Answer 9

1. Based on throughput.
   Reduced with time if results satisfactory.
2. Excision of neck skin. 5 samples per session. 1 sample = 3 skins.
3. After 1.5hours chilling.

Question 10

1. Sampling requirements for processed meat.
2. Establishment sampling frequency?

Answer 10

1. 5 samples for testing from a single batch each week.
   No statutory testing required for establishments that generate <2 tonnes of product intended to be eaten cooked per week.
   Ready-to-eat products, i.e. steak tartare, required to be tested every week for Salmonella – for any amount produced.
2. No establishment sampling frequency for meat products – Food Business Owner to decide based on perception of risks involved.

Question 11

1. Food Safety Criteria for processed meats.
2. Process Hygiene Criteria for processed meats.

Answer 11

1. Absence of Salmonella in a designated mass of product – dept on the type of processed meat. – Have to reject the whole lot if Salmonella present.
2. Quantity of APC and/or E. coli dept on type of processed meat.

Question 12

1. What happens as a result of failure to meet Food Safety Criteria?
2. What happens as a result of failure to meet Process Hygiene Criteria?

Answer 12

1. Food Business Owner should not place the food on the market.
   Product may need to be recalled.
2. Product can be placed on the market but production process needs to be reviewed e.g. HACCP.

Question 13

What are rapid methods of testing food premises?

Answer 13

Swabbing methods in food production areas to monitor cleanliness of food-contact surfaces may be used in abattoir.
– Protein detection:
- Colour reactions for protein levels in 1-10 mins.
- Pro-tect, Flash.
– ATP bioluminescence.
- Examines total ATP levels using a luminometer (10 mins).
– VerifEYE system being screened for use on red meat carcasses in the UK. - Used in US.
- Detects chlophyll products found in faeces of ruminants and shows as a fluorescence on monitor - Could be used for some surfaces.
- Provides real-time info and is easy to use.

Question 14

1. Types of microorganisms found in foods.
2. What are the 2 categories of food-borne disease caused by these microorganisms?
3. What microorganism types dominate to cause food spoilage?
4. Main factors affecting spoilage rates of foods?

Answer 14

1. Bacteria, moulds, yeasts, viruses, parasites, prions.
2. Infections
   Intoxications.
3. Bacteria, yeasts, moulds.
4. Initial level of contamination and storage conditions.

Question 15

1. Meat contamination source?
2. Dairy contamination source?
3. How can rodents and birds act as sources of contamination?
4. How can food handlers act as sources of contamination?
5. How can equipment and utensils act as sources contamination?

Answer 15

1. Bacteria carried in the guts of animals can contaminate outside of the animal by transfer to the carcass during dressing. Cleanest are pigs then sheep then cattle.
2. Contamination during milking, pasteurisation problems, contamination post-pasteurisation.
3. Carrying bacteria in faeces; shedding into food areas.
4. Organisms carried naturally on the skin, in the nose, poor personal hygiene, handling of foods.
5. Cross-contamination between foods and surfaces; proper cleaning not carried out.

Question 16

1. Processing as a food contamination source.
2. Soils as a contamination source.
3. Water as a contamination source.
4. Environment as contamination source.

Answer 16

1. • Extra ingredients added to foods.
     - Airborne contamination.
2. Contamination from the vegetables.
3. Non-potable water used for washing.
4. Bacteria EVERYWHERE!

Question 17

Basics needed for microbial growth?

Answer 17

Appropriate nutrients available.
Available water.
Environment optimum to growth:
- Temperature.
- pH.
- Oxygen levels.
No competition from other organisms.
Time.

Question 18

1. Intrinsic factors affecting microbial growth in foods.
2. Extrinsic factors affecting microbial growth in foods.

Answer 18

1. Concerning the physical, chemical and biological properties of food.
   Food structure, types/levels of nutrients, antimicrobials, water activity, pH, buffering capacity, redox potential.
2. Resulting from the physical and chemical properties of the environment in which the food is kept.
   Temperature and humidity of storage, atmosphere e.g. removal of O2 from storage.

Question 19

1. Processing factors affecting microbial growth in foods.

Answer 19

1. • Effects as a result of processes applied during manufacture of the food.
     - Physical treatment e.g. heat.
     - Chemical treatment e.g. addition of acids.
     - Increase in microbes – e.g. introduction of microbes from the equipment.

Question 20

1.Result of the growth of microorganisms in the food.
2. What is spoilage determined by?

Answer 20

1. Chemical changes in the food.
   - These are detected before microbes are detected.
   - Yeasts produce chemicals quicker than bacteria due to the cell volume = quicker spoilage.
   Presentation is offensively evident to the senses.
2. Organisms present and numbers, food type, intrinsic, extrinsic, implicit and processing factors.

Question 21

1. What compounds can result from spoilage process of proteinaceous foods e.g. meat?
2. What compounds can result from spoilage process of fish?
3. What is observed in terms of pH during spoilage?

Answer 21

1. Ammonia, ethanol, acetate, indole, acetoin, amines, esters, sulphides, mercaptans.
2. As for meat but + histamine.
3. Increase in pH.

Question 22

1. What is observed in carbohydrate foods in spoilage?
2. What is observed in fatty foods in spoilage?

Answer 22

1. Ferment rather than putrefy; acid production (lactic and acetic mainly) and gas production.
   pH decrease due to acid production.
2. Release of fatty acids by hydrolysis; only offensive when butyric, capric and caproic acids produced.
   Off flavours result from ketone production.

Question 23

Indications. Give the causes.
1. Ammonia or sulphur smell, chalky taste.
2. Tainting, souring, putrefaction.
3. Slime formation, bad odour, rancid flavour, colour change (grey, brown, green).
4. Sticky surface.
5. Whiskers.
6. Surface colourations (cream, black, green).

Answer 23

1. Degradation of protein, fats and carbohydrates.
2. Anaerobic bacterial spoilage.
3. Bacterial and yeast spoilage.
4. Mould spoilage.
5. Mould spoilage.
6. Mould spoilage.

Question 24

1. Give examples of naturally occurring substances in foods that naturally inhibit microorganisms.

Answer 24

1. Lysozyme in milk and egg white.
   Lactoperoxidase system consisting of 3 components in cows milk.
   Essential oils such as eugenol (cloves), allicin (garlic), allyl isothiocyanante (mustard), thymol (sage and oregano).

Question 25

1. Examples of antimicrobials produced by bacteria.

Answer 25

1. Lactic acid produced by lactic acid bacteria.
   Bacteriocins produced by Lactococcus lactis (Nisin).
   Antibiotics produced by non-lactic acid bacteria.
   Hydrogen peroxide produced by lactic acid bacteria when oxygen present.

Question 26

1. What is water activity?
2. What is the goal water activity to inhibit microorganism survival and growth?
3. Water activity of: - pure water
   - 22% NaCl solution.
4. What does lowering water activity do?
5. What affects water activity?

Answer 26

1. Water available for microorganism NOT water content of the food.
2. <0.5.
3. Pure water = 1.00
   22% NaCl solution = 0.86.
4. Increases lag phase, decreases growth rate, size of final population and spore germination.
5. Environmental e.g. temperature and additives.

Question 27

How can pH be used to preserve food?

Answer 27

Lower pH of food to a level that will not support microbial growth by the addition or production of acids.
- Fermentation by addition of LAB in milk, yoghurt, cheese, meats.
- Pickling by addition of acids such as acetic acid to vegetables such as onion and cabbage etc.

Question 28

How can low temperature be used to preserve foods?

Answer 28

Refrigeration
Growth rates are reduced or growth does not occur at lower temperatures.
But is not a sterilisation.
Only effective for certain amount of time.
Some bacteria can grow very well in this environment.

Freezing
Moulds and yeasts cannot grow on frozen food stored below -12C.
Some survival – trapped water pockets that do not freeze.
– Bacterial spores and toxins.
– Trichinella spiralis cysts in meat (up to 15.2cm diameter.
–> Must be stored at -15C for 15 days, -23.3C for 10 days, or -28.9C for 6 days.
Slow spoilage of frozen foods such as meat is due to enzyme systems remaining active e.g. lipases.

Question 29

How can high temperature be used to preserve foods?

Answer 29

Pasteurisation.
– Destruction of all disease-producing organisms (e.g. milk).
– Destruction/reduction of spoilage organisms (e.g. vinegar).

Sterilisation (e.g. canned food)
– Destruction of all viable organisms as may be detected by the usual cultural methods employed.

Question 30

Hurdle effect.

Answer 30

Likely to be combo of different factors occurring within the food.
Combo of factors will have more of an effect on bacterial growth.
So more than one factor must be employed to limit or eliminate bacterial growth.