Preventing Cross Contamination and Temperature Control
Preventing Cross Contamination & Temperature Control
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Preventing Cross Contamination & Temperature Control
Learning Objectives
Safe Food Practices
Describe safe handling techniques, personal hygiene rules, and colour-coded equipment systems.
Temperature Rules
Explain the critical role temperature control plays in preventing bacterial multiplication.
The Danger Zone
Identify the UK Temperature Danger Zone (5°C to 63°C) and restrict food exposure duration.
Thermal Controls
Apply UK legal standards for safe cooking, chilling, hot holding, reheating, and temperature logging.
What is the definition of Cross-Contamination?
What is Cross Contamination?
Definition:
The transfer of harmful bacteria, viruses, or hazardous substances from contaminated sources (raw food, surfaces, pests, handlers) to ready-to-eat food.
CONTAMINATION ROUTE FLOW:
Microbiological
Bacteria (Salmonella, E. coli), viruses, moulds.
Chemical
Cleaning products, pest chemicals, grease.
Physical
Glass, plastic, hair, metal fragments, pests.
Allergen
Unintended transfer of 14 major allergens.
Raw Chicken
Unwashed Hands
Ready-to-Eat Salad
The 4 Key Food Safety Hazards:
Safe Food Handling Practices
Essential Handling Controls
Hygiene & Cleanliness Standards
Minimise Physical Contact: Handle food as little as possible, only using tongs, scoops, or ladles. Gloves worn if with hands
Dedicated Preparation Areas: Physically separate raw meat butchery from cooked food slicing zones.
Keep Food Covered: Store all ingredients in food-grade container lids or wrap when not in active prep.
Clean Utensils Only
Clean As You Go Routine
Single-Use Paper Towels
Immediate Spillage Response
Correct vs Incorrect Practices
Storage of Raw Chicken in comparison to Cooked Meats or Salads
Correct vs Incorrect Practices
Usage of Knives & Boards for Raw Meat and Cooked Meat in same area at the same time
Correct vs Incorrect Practices
Use of towels for wiping down surfaces and drying hands
Raw vs Ready-to-Eat Separation
INCORRECT PRACTICE (High Risk)
CORRECT PRACTICE (Food Safe)
Storing raw chicken on top shelf above cooked meats/salads.
Using the same knife and board for raw beef and then slicing sandwich cheese.
Reusing tea towels to wipe down surfaces and then dry hands.
Store raw meat strictly on bottom fridge shelves in covered containers.
Use designated colour-coded boards (Red for raw meat, White for dairy/bakery).
Clean and sanitise worktops with 2-stage cleaning between tasks.
Colour Coding & Personal Hygiene
Industry standard HACCP chopping board system & food handler standards
RED
Raw Meat
BLUE
Raw Fish
YELLOW
Cooked Meat
GREEN
Salad/Fruit
BROWN
Vegetables
WHITE
Dairy/Bread
PURPLE
Allergens
Personal Hygiene Mandates
Hand Washing: 20-second wash with warm water & anti-bacterial soap.
Protective Clothing: Clean apron/uniform; change if dirty.
Hair Controls: Hairnets/hats worn; long hair tied back completely.
Jewellery Policy: Plain wedding band only; no watches, rings, or stone settings.
Other Safe Working Practices
Washing Fruit & Produce
Wash all salad ingredients, fruits, and vegetables thoroughly under running drinking-quality water before prep to eliminate soil, pesticides, and surface pathogens (e.g. E. coli).
Dual-Use Equipment Warning
Complex equipment (e.g., slicers, vacuum packers, mincers) should NOT be dual-used for raw and ready-to-eat foods unless completely dismantled, cleaned, and thermal-sanitized.
Chemical Safety & Sanitising
Store cleaning chemicals strictly away from food in locked cupboards. Use food-safe sanitisers.
Allergen Cross-Contamination
Prevent allergen cross-contamination by using clean purple utensils/boards. Even tiny traces of allergens (e.g., peanut dust, sesame oil) can trigger severe anaphylactic reactions.
Which practice best helps prevent cross-contamination in a kitchen?
Shared utensils
Colour-coded boards
Open storage
Warm holding
Which item is the best way to stop loose hair contaminating food during preparation?
Apron
Hairnet
Gloves
Tea towel
Bacteria - Good Vs Bad
Why Temperature Control Matters - Bacteria
Bacterial Multiplication
Spores & Bacterial Toxins
BACTERIAL EXPONENTIAL GROWTH TIMELINE: Binary FIssion
Bacterial Spores: Defensive protective shells formed by bacteria (e.g. Bacillus cereus in rice) that survive normal cooking heat.
Bacterial Toxins: Poisons produced by bacteria (e.g. Staphylococcus aureus) that may not be destroyed by reheating.
Chilling Effect: Cold temperatures (below 5°C) do not kill bacteria but stop or dramatically slow down their multiplication.
Start 1 cell
20 Mins 2 cells
40 Mins 4 cells
7 Hours 2 Million+
The Temperature Danger Zone
UK Standard Danger Zone: 5°C to 63°C – Restrict exposure time
100°C - Boiling Point
75°C - Safe Cooking
63°C - Hot Holding Threshold
DANGER ZONE (5°C - 63°C)
5°C - Max Fridge Temp
-18°C - Safe Commercial Freezer
Why 5°C - 63°C is Critical
Bacteria thrive and multiply rapidly in this band. Most food poisoning organisms multiply fastest at human body temperature (~37°C).
The 2-Hour / 4-Hour Rules
Keep ambient prep time under 20 mins. If high-risk food remains in the Danger Zone for over 4 hours, it MUST be discarded under UK law.
Safe Food Temperatures Guide
Recommended UK target temperatures across food operational stages
Probe Calibration
Monitoring Temperature
Probe thermometer procedures, calibration & temperature record logs
Probe Cleaning: Disinfect probe with anti-bacterial probe wipes before and after every single use.
Recording Temperature: Insert probe into thickest part of food (avoiding bones or container sides).
2-Point Calibration:
• Ice Test: 0°C (±1°C) in melting ice water slurry. • Boiling Test: 100°C (±1°C) in boiling water.
Record Keeping: Log fridge/freezer temps twice daily; log cooking/hot-holding temps every batch.
Sample Log Sheet Entry:
Time: 12:15 Item: Beef Stew Temp: 78.4°C Action: Passed / Served
Temperature Control in Transit - (Hot food > 63°C, Cold food ≤ 8°C).
Mandatory Delivery Rejection
Safe Serving Practices Active temperature monitoring and recording must continue seamlessly from transport unit to serving stations.
Transporting & Receiving Food
Regular Monitoring
Record fridge unit temperatures at scheduled intervals daily. Operating targets should remain strictly between 1°C and 5°C.
Threshold Exceeded (>8°C)
If fridge temperatures rise above 8°C, high-risk foods stored within must be immediately discarded for consumer safety.
Maintenance Issues
Letting Supervisors know if there is any issue with Fridges, for Maintenance teams to fix
Fridge Monitoring & Thresholds
Practical Workplace Scenarios
Real-world decision making: What should you do in these situations?
Scenario 1
Raw Chicken above Salad
During morning checks, you notice raw chicken breast packs placed on the top shelf directly above prepared salad bowls in the walk-in fridge.
What should you do?
Scenario 2
Soup Reheating Test
You probe a batch of reheated tomato soup intended for lunch service. The probe thermometer displays a core temperature of 32°C.
What should you do?
Scenario 3
High Delivery Temp
A refrigerated delivery van arrives with fresh vacuum-packed salmon fillets. Your probe checks the core fish temperature at 11.2°C.
What should you do?
Key Takeaways Summary
Cross Contamination Controls
Temperature Control Rules
Separate: Raw meat at the bottom; ready-to-eat food on upper shelves.
Clean & Sanitise: Follow 2-stage cleaning with approved chemicals.
Colour Code: Strictly use designated boards and knives for each food category.
Hygiene First: Thorough 20-second hand washing and zero bare-hand contact with Ready-to-eat food.
Avoid Danger Zone: Keep high-risk food outside 5°C to 63°C.
Cook Thoroughly: Ensure core temperature reaches 75°C (or equivalent).
Chill Rapidly: Cool hot dishes to under 8°C within 90 minutes.
Monitor & Log: Probe core temps with clean wipes and record on log sheets.
In food safety, what temperature range is known as the danger zone for bacterial growth?
5°C to 63°C
0°C to 5°C
63°C to 75°C
-18°C to 0°C
During a morning check, a fridge is recorded at 15°C. What should you do immediately?
Keep using it
Adjust the shelves
Report and discard food
Record it later
Any Questions?
Thank you for participating in Level 2 Food Hygiene & Safety Training!
