For many years I had a typical electric kettle. Whenever I wanted a 75 Celsius / 167 Fahrenheit water to make a green tea, I had to boil it up to 100 Celsius / 212 Fahrenheit (because, that was the temperature, where each my kettle was stopping to heat) and wait.
Now, I've got an electric kettle with a thermometer. Can I boil the water only to 75 Celsius and stop? What is the typical temperature, in which all (most of) germs in water are killed and water becomes drinkable?
I've heard, that this is 70 Celsius / 158 Fahrenheit, so my idea would have a ground. Am I right?
Best Answer
Technically, your idea seems sound. But I wouldn't do it.
What you are proposing to do in your electric kettle is very close to the standards for flash pasteurization. According to wikipedia, the standard procedure for flash pasteurization is to heat and circulate the liquid at 71.5 °C (160 °F) to 74 °C (165 °F), for about 15 to 30 seconds, which results in a five log (99.999%) or greater reduction in bacteria. Other journal articles seem to indicate that some protozoa like cryptosporidium are killed by flash pasteurization, but others, like giardia, might survive in small numbers.
I suspect the guideline for boiling water in issues of safety and in recipes is used because steam and bubbles are such convenient guarantors of temperature.
Psychologically, though, this makes me a little nervous. Personally, I would boil the water- if you have time for tea, you have time to boil water. It is possible, though, that you are a more adventurous tea drinker than I am.