Quiz of the Day
Food Safety & Science
Sunday, 7 June 2026
World Food Safety Day — food science, bacteria facts, kitchen myths busted
1. World Food Safety Day is observed on 7 June. Which UN agencies jointly lead the campaign?
- WHO and FAO
- FAO and UNESCO
- WHO and UNICEF
- WHO and WFP
The World Health Organization and Food and Agriculture Organization estimate that unsafe food causes 600 million illnesses and 420,000 deaths per year. That means roughly 1 in 10 people worldwide fall ill from contaminated food annually.
2. What is the 'danger zone' temperature range where bacteria multiply fastest in food?
- 50-80 degrees C
- 20-40 degrees C
- 0-10 degrees C
- 8-63 degrees C
In ideal conditions, a single bacterium can divide every 20 minutes. That means one bacterium could theoretically become over 2 million in just 7 hours at room temperature. This is why the 'two-hour rule' for leaving food out exists.
3. Is the 'five-second rule' for dropped food scientifically valid?
- Yes, bacteria need at least 5 seconds to transfer
- Yes, but only on dry surfaces
- No, bacteria can transfer to food almost instantly
- It depends on the type of food
Rutgers University research showed that bacteria transfer to food within less than one second of contact. Moist foods on smooth surfaces pick up the most bacteria. However, the type and amount depends on how contaminated the floor is in the first place.
4. Which foodborne bacterium is most commonly associated with raw chicken?
- E. coli
- Salmonella
- Staphylococcus
- Listeria
Up to 65% of raw chicken in supermarkets may carry Salmonella. This is why you should never wash raw chicken — splashing can spread bacteria up to 1 metre around your sink. Cooking to 74 degrees C kills it reliably.
5. What is pasteurisation named after?
- A French city
- A Latin word for 'clean'
- Scientist Louis Pasteur
- A type of bacteria
Pasteur developed the process in 1864 originally to prevent wine and beer from spoiling. It was later applied to milk, saving countless lives. Before pasteurisation, contaminated milk was one of the leading causes of infant mortality in cities.
6. What is the most important single thing you can do to prevent foodborne illness?
- Cook food well done
- Wash your hands properly
- Buy organic food
- Refrigerate everything
Proper handwashing with soap for 20 seconds can reduce foodborne illness by up to 47%. Yet studies using hidden cameras have shown that only about 5% of people wash their hands correctly after using the toilet.
7. What does 'use by' on a food label mean compared to 'best before'?
- 'Use by' is about safety; 'best before' is about quality
- They mean the same thing
- 'Best before' is stricter than 'use by'
- 'Use by' is a suggestion; 'best before' is a legal requirement
Confusion between these dates causes enormous food waste — an estimated 10% of the EU's 88 million tonnes of annual food waste is linked to date labelling misunderstandings. Many perfectly safe foods are thrown away because people treat 'best before' as an expiry date.
8. What common kitchen item harbours more bacteria than a toilet seat?
- Fridge handle
- Kitchen sponge
- Chopping board
- Oven knob
A kitchen sponge can harbour up to 54 billion bacteria per cubic centimetre — making it the single dirtiest item in most households. Microwaving a wet sponge for 2 minutes kills 99% of bacteria, but replacing sponges weekly is even better.
9. Which preserving method works by removing water from food to prevent bacterial growth?
- Smoking
- Fermentation
- Dehydration
- Pickling
Humans have been drying food for at least 12,000 years. Bacteria need a water activity of at least 0.85 to grow. Properly dehydrated food can last years — NASA uses freeze-dried food for space missions, and some dried foods found in Egyptian tombs were still edible.
10. What is Clostridium botulinum, and why is it dangerous?
- A virus that causes stomach flu
- A mould that grows on bread
- A parasite found in undercooked pork
- A bacterium that produces one of the most potent toxins known
Botulinum toxin is so powerful that a single gram could theoretically kill 1 million people. Ironically, in tiny doses it is Botox — the cosmetic treatment. Improperly canned food is the main risk; the bacterium thrives in low-oxygen environments.
11. Is it safe to refreeze food that has been thawed?
- Only for vegetables
- Never — it is always dangerous
- Only if you cook it first
- Yes, if it was thawed in the fridge and has not been left at room temperature
This is one of the most persistent kitchen myths. If food was thawed safely in the fridge (below 5 degrees C), bacteria will not have multiplied to dangerous levels, so refreezing is safe. Texture may suffer, but it will not make you ill.
12. What food safety innovation did Napoleon's army inspire?
- Canning
- Refrigeration
- Vacuum packing
- Pasteurisation
In 1795, Napoleon offered a 12,000 franc prize for a food preservation method for his armies. Nicolas Appert won it in 1810 by sealing food in glass jars and heating them. He did not understand why it worked — Pasteur's germ theory came 50 years later.
13. Which common food can be dangerous if reheated improperly?
- Rice
- Potatoes
- Bread
- Pasta
Uncooked rice contains spores of Bacillus cereus that survive cooking. If cooked rice is left at room temperature, these spores germinate and produce toxins that reheating cannot destroy. It causes 'fried rice syndrome' — up to 63,000 cases per year in the UK alone.
14. What colour chopping board system is used in professional kitchens for raw meat?
- White
- Blue
- Green
- Red
The colour-coding system prevents cross-contamination: red for raw meat, blue for raw fish, green for salad and fruit, yellow for cooked meat, brown for vegetables, and white for bakery/dairy. This simple system has dramatically reduced foodborne illness in commercial kitchens.
15. Approximately how much food is wasted globally each year?
- About 2 billion tonnes
- About 1 billion tonnes
- About 1.3 billion tonnes
- About 500 million tonnes
That is roughly one-third of all food produced for human consumption. If food waste were a country, it would be the third-largest emitter of greenhouse gases after China and the USA. Meanwhile, 828 million people go to bed hungry every night.