Kitchen Hygiene: Washing Up and Cleaning Routines

1What makes cleaning work: Sinner's circle

In 1959 a German chemist, Herbert Sinner, described four factors that together decide how well anything is cleaned. They are shown as four parts of a circle, often called Sinner's circle:

1. Chemistry: the soap or detergent, which loosens grease so water can carry it away.
2. Temperature: hot water melts fat and speeds up the action of the detergent.
3. Mechanical action: scrubbing, rubbing and scraping, which knock the dirt loose.
4. Time: how long the detergent is in contact with the dirt, for example soaking a burnt pot.

Water, the fifth element, carries all four. The key idea: if one factor is small, make another one bigger. If there is no hot water, scrub harder or soak longer. If a pot has soaked overnight, it needs less scrubbing.

2Washing up by hand, step by step

1. Scrape leftover food into the compost or bin. Food left on plates makes the water dirty at once.
2. Soak pots with dried or burnt food in warm water while you wash the rest (time does the work).
3. Wash in hot water with detergent, in this order: glasses and cups first, then cutlery, then plates and bowls, then serving dishes, and the greasy saucepans and frying pans last. Cleanest items go first, so they are not washed in greasy water. Change the water when it becomes greasy or cool.
4. Rinse in a second basin of clean water to remove the soap and loosened dirt.
5. Sanitise where many people share the dishes, as in a school or restaurant: dip the rinsed items in very hot water or in a sanitiser at the strength shown on its label.
6. Air-dry on a clean rack, in the sun if possible. A tea towel that has already been used spreads germs back onto clean plates.
7. Store dry items upside down or covered, away from dust and flies.

Restaurants follow the same idea with a three-basin method (or three-compartment sink): wash, rinse, sanitise. Water that your hands can bear is only about 40 °C, which is too cool to kill germs on its own; this is why the separate sanitising step, or a machine that rinses with very hot water, is used where many people eat.

3Cloths, sponges and brushes

• Bacteria multiply quickly in a warm, damp cloth or sponge full of food bits.
• Use separate cloths for dishes, for work surfaces and for the floor; colour-coding makes this easy.
• Wash cloths every day in hot soapy water, rinse, and dry them in the sun. Boiling a cloth for a few minutes kills most germs.
• Replace sponges and scourers often, and never leave them lying in a wet sink.

4A kitchen cleaning schedule

A cleaning schedule is a plan that says what is cleaned, how often, and by whom. It makes sure no job is forgotten.

5Keeping pests out

Kitchen pests are animals that spoil food and spread germs: flies, cockroaches, ants, rats and mice. Signs of pests are droppings, gnawed sacks, smear marks along walls and egg cases in corners. Every pest needs three things, so take all three away:

• Food: keep food covered or in sealed containers; sweep up crumbs; keep bins closed.
• Water: fix dripping taps; do not leave water standing in the sink or in old containers.
• Shelter: seal cracks and holes; clear clutter and empty sacks; keep store rooms tidy.

Do not spray insecticide near food or dishes, because that adds a chemical hazard. If rats keep returning, ask a trained pest-control worker.

Worked example: washing up with cold water

Task: Keza has fried sambaza for supper. She has only cold water from the jerrycan, bar soap and a scouring pad. Use Sinner's circle to explain how she can still get the greasy frying pan clean, and put her washing-up in order: frying pan, cups, spoons and forks, plates.

Solution: The temperature factor is low, so she must increase the others. Time: soak the pan with soapy water while she washes the other items. Mechanical action: scrub it hard with the scouring pad. Chemistry: use enough soap, and wipe out the loose oil with a piece of paper first so the soap is not used up by the grease. If she can spare fuel, warming a little water in the pan itself also helps.

Order: cups → spoons and forks → plates → frying pan (least greasy first, greasiest last).

Practice