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Food contamination has no five-second boundary

A laboratory study tested several contact times, foods, and surfaces, finding that time was only one part of bacterial transfer. How many bacteria move onto food and whether someone subsequently becomes ill are different questions; this experiment measured the former.

3–7 min

Questions you could explore

  • Why might a wet piece of fruit and a dry food pick up different amounts from the same surface?
  • How could an experiment compare contact time while controlling the food and surface?

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Food

Why bread dough rises

The holes in a slice of bread are a record of what happened inside the dough. In ordinary yeast-raised wheat bread, making gas is only part of the story: the dough also has to hold it.

3–5 min

Why bread dough rises

Food3–5 minThe holes in a slice of bread are a record of what happened inside the dough. In ordinary yeast-raised wheat bread, making gas is only part of the story: the dough also has to hold it.

Food

How does milk become yogurt?

Yogurt begins with milk, but its tang and texture develop as starter bacteria change the mixture. Their use of milk sugar and the resulting acidity connect the microbial activity with what ends up on the spoon.

3–5 min

How does milk become yogurt?

Food3–5 minYogurt begins with milk, but its tang and texture develop as starter bacteria change the mixture. Their use of milk sugar and the resulting acidity connect the microbial activity with what ends up on the spoon.

Food

Keeping oil and water together in mayonnaise

Pour oil and water into a jar, shake them hard, and they will quickly separate back into two layers. Yet mayonnaise stays a thick, stable sauce because vigorous whisking breaks the oil into microscopic droplets, while emulsifiers in the egg yolk coat those droplets and stop them from recombining.

3–5 min

Keeping oil and water together in mayonnaise

Food3–5 minPour oil and water into a jar, shake them hard, and they will quickly separate back into two layers. Yet mayonnaise stays a thick, stable sauce because vigorous whisking breaks the oil into microscopic droplets, while emulsifiers in the egg yolk coat those droplets and stop them from recombining.

Food contamination has no five-second boundary | Speech Topic | speaking.app