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Hong KongCleaning and sanitizing: two different jobs, nine questions
Nine of the eighty questions, split across writing cleaning procedures, storing the chemicals and tools, and carrying the procedures out. Cleaning removes soil; sanitizing reduces pathogens on an already-clean surface.
Cleaning and sanitizing are two operations, and half the wrong answers in this area depend on you treating them as one.
Cleaning removes visible soil. Sanitizing reduces pathogens to a safe level on a surface that is already clean. Sanitizer applied to a dirty surface does very little, which is the point behind the sequence rather than a piece of trivia about it.
The three-compartment sink
Scrape, wash, rinse, sanitize, air dry. Five steps, three sinks, and the last one is the step people drop.
Air dry. Not towel dry. A cloth reintroduces exactly what the sanitizer just removed, and the exam asks about it because kitchens do it constantly.
Wash water starts at 43°C (110°F) minimum. If the sanitizing step uses hot water immersion instead of a chemical, that is 77°C (171°F) for 30 seconds.
Sanitizer concentrations
| Sanitizer | Concentration | Contact time |
|---|---|---|
| Chlorine | 50 to 100 ppm | 7 seconds at 100 ppm and 24°C (75°F) |
| Quaternary ammonium | 200 to 400 ppm, per the label | 30 seconds |
| Iodine | 12.5 to 25 ppm, pH 5.0 or less | 30 seconds |
Three numbers to hold, and they are worth holding precisely. Stronger is not better: chlorine above the range is a chemical hazard and can leave residue, which the Code treats as contamination.
A sanitizer you cannot measure is not a control. The strips have to match the sanitizer - chlorine strips do not read quats - and questions about a manager who has strips for the wrong chemical do appear.
Temperature, concentration, contact time, pH, water hardness
Five factors affect whether a chemical sanitizer works. Too cold and it under-performs; too hot and chlorine evaporates. Hard water interferes with quats. Iodine needs an acidic pH.
The exam rarely asks you to recite the five. It asks a scenario in which one of them has gone wrong and expects you to spot which.
Dishmachines
A high-temperature machine has to reach 71°C (160°F) measured at the utensil surface, which is not the same as the gauge reading on the front and is why an irreversible temperature indicator exists. A chemical machine dispenses sanitizer at the concentration on the label.
How often
Food-contact surfaces in continuous use with TCS food at room temperature get cleaned and sanitized every 4 hours. Between raw and ready-to-eat use, always. When the task changes, always. At the end of the shift, always.
Wiping cloths for food-contact surfaces are stored in sanitizer solution between uses, not on the edge of the counter and not in a pocket.
Storing the chemicals
Three of the nine questions are about storage and maintenance of cleaning materials, which is more than the sub-area sounds worth. Chemicals sit below and away from food, equipment and single-use items. Working containers carry the common name of the contents. Cleaning tools have their own storage, and mop water goes down the service sink.
Common questions
What is the difference between cleaning and sanitizing?
Cleaning removes visible soil. Sanitizing reduces pathogens on a surface that is already clean. Sanitizer on a dirty surface does very little, which is why the order matters rather than being arbitrary.
What are the steps in a three-compartment sink?
Scrape, wash, rinse, sanitize, air dry. Air drying is the step most often dropped, and towel drying undoes the sanitizing step by reintroducing what it just removed.
What concentration should chlorine sanitizer be?
50 to 100 ppm, with 7 seconds of contact at 100 ppm and 24°C (75°F). Higher is not better - above the range it becomes a chemical hazard and can leave residue on the surface.
How often must food-contact surfaces be sanitized?
Every 4 hours when in continuous use with TCS food at room temperature, and always between raw and ready-to-eat use, when the task changes, and at the end of the shift.
Do you need sanitizer test strips?
Yes. A sanitizer with no way to measure it is not a control. The strips must match the chemical - chlorine strips will not read quaternary ammonium, and that mismatch appears in exam questions.