There is good reason to think that the Torah Sages knew the principle of pasteurization and the use of heat to destroy bacteria.
The Talmud emphasizes the importance of drinking liquids that have been heated to boiling. The Sages go so far as to say (Baba Metziah 29b):
“R. Yochanan said: [Drink] a cupful of witchcraft, but not a cupful of tepid water.”
In other words: It is preferable to drink even a witch’s brew than a cup of unboiled water, because the latter can be so damaging to human health.
Along these lines, the Sages made another point – as yet to be confirmed by modern science:
“[R. Yochanan's statement quoted above] applies only to a metal utensil, whereas there is no problem with an earthenware one. And even of a metal utensil, it holds true only if [the water] is unboiled; but if it was boiled [and subsequently cooled down], there is no problem. Moreover, this is only if one does not put herbs or spices in it, whereas if he does, there is no objection.”
(Despite this explanation, we should note Maimonides’ comments in his Guide for the Perplexed (Part 3, chap. 14), that the Sages’ statements about human health must be reexamined in each generation, to verify that the human physiology or the nature of the plants or medicines mentioned have not subsequently changed.)
Herein lays a challenge for contemporary scientists – to use the tools at their disposal to verify the information presented in the Sages’ comments quoted above.