WSQ Cross-Contamination Prevention 2 — Questions and Answers
Question 1: What is the correct way to prevent cross-contamination when wiping down surfaces in a kitchen?
- Use designated colour-coded or separate cloths for different surfaces, change and sanitise cloths frequently, and use disposable paper towels where possible (Correct answer)
- Use one multipurpose cloth for all surfaces to save time
- Wiping surfaces with a dry cloth is sufficient
- Use the same cloth for all surfaces but dip it in hot water between uses
Correct answer: Use designated colour-coded or separate cloths for different surfaces, change and sanitise cloths frequently, and use disposable paper towels where possible
Using the same cloth across multiple surfaces spreads contamination from one area to another. Best practice requires using separate, colour-coded cloths for different areas (e.g., food contact surfaces vs. non-food surfaces), sanitising cloths frequently, and preferring single-use paper towels for food contact surfaces.
Question 2: How should cleaning chemicals be stored in a food establishment to prevent contamination?
- In a clearly labelled, separate, locked storage area away from food, food preparation areas, and food contact equipment (Correct answer)
- Under the food preparation bench for convenient access
- In the same refrigerator as food items if the containers are sealed
- In the food storage area as long as they are clearly labelled
Correct answer: In a clearly labelled, separate, locked storage area away from food, food preparation areas, and food contact equipment
Cleaning chemicals, sanitisers, and pest control products must be stored in a separate, clearly labelled, and ideally locked area completely away from food, food preparation areas, and food contact surfaces. Chemical contamination can cause serious illness and is a major food safety hazard.
Question 3: What is the risk of using the same cooking oil repeatedly over many cycles without changing it?
- The oil degrades, producing harmful compounds such as acrylamide and polar compounds that can contaminate food and pose health risks (Correct answer)
- Old oil only affects the taste and appearance of food, not safety
- Oil can be used indefinitely if it is filtered after each use
- The only risk is increased calorie content of fried food
Correct answer: The oil degrades, producing harmful compounds such as acrylamide and polar compounds that can contaminate food and pose health risks
Repeatedly using cooking oil at high temperatures causes degradation, producing harmful polar compounds and acrylamide (a probable carcinogen). Singapore's SFA has guidelines on oil degradation limits, and food establishments should change oil regularly and monitor oil quality using test kits.
Question 4: Why must raw seafood be stored separately from other foods in a refrigerator?
- Raw seafood can harbour pathogens like Vibrio and Salmonella, and their juices can drip onto and contaminate other foods (Correct answer)
- Seafood only needs to be stored separately for odour control
- Separation is required only for shellfish, not for fish fillets
- Raw seafood can be stored on the same shelf as cooked food if individually wrapped
Correct answer: Raw seafood can harbour pathogens like Vibrio and Salmonella, and their juices can drip onto and contaminate other foods
Raw seafood commonly carries pathogens including Vibrio vulnificus, Vibrio parahaemolyticus, and Salmonella. Storing raw seafood above or near other foods risks drip contamination. It should be stored in sealed containers on the lowest shelves, separate from cooked and ready-to-eat foods.
Question 5: What is 'environmental contamination' as a source of cross-contamination in food preparation?
- Contamination originating from the kitchen environment itself — including unclean surfaces, equipment, air, pest droppings, and contaminated water — transferring to food (Correct answer)
- Contamination that only occurs outdoors
- Pollution from outside the food establishment entering through ventilation
- Contamination from packaging materials only
Correct answer: Contamination originating from the kitchen environment itself — including unclean surfaces, equipment, air, pest droppings, and contaminated water — transferring to food
The kitchen environment itself can be a source of contamination — unclean floors, walls, and surfaces harbour bacteria; pest droppings contaminate surfaces; contaminated water spreads pathogens; and dust or condensation can transfer contaminants to food. Environmental hygiene is a prerequisite for food safety.
Question 6: What is the CORRECT cleaning sequence to prevent cross-contamination on food contact surfaces?
- Remove food debris, clean with detergent and warm water, rinse with clean water, then sanitise with an approved food-safe sanitiser (Correct answer)
- Apply sanitiser directly without pre-cleaning
- Clean with hot water only, then air dry
- Apply sanitiser, then clean with detergent — sanitising first, then cleaning
Correct answer: Remove food debris, clean with detergent and warm water, rinse with clean water, then sanitise with an approved food-safe sanitiser
The correct sequence is: (1) remove food debris, (2) clean with detergent and water to remove grease and organic matter, (3) rinse to remove detergent residue, (4) sanitise with an approved food-safe sanitiser. Sanitisers cannot work effectively if organic matter is not first removed by cleaning.
WSQ Cross-Contamination Prevention 2
What is the correct way to prevent cross-contamination when wiping down surfaces in a kitchen?