Tom: Is that true if you refrigerate the garlic infused oil after it is strained? I have been doing this for decades and never got ill. Thanks. Walter
C. Botulinum bacteria is virtually everywhere, and it produces the most deadly toxin known on earth. Heat will kill the bacteria, but it will not eradicate the toxins in the spores produced by the bacteria.
It requires an environment with minimal oxygen to produce the deadly spores/toxin.
Both Garlic & Potatoes are very high risk items if kept in a low/no oxygen environment such as oil, or wrapped in something to limit oxygen contact. It does not produce any unusual scent or flavor characteristics in tainted foods.
I am unsure about the strained oil posing a risk, I go by the safety rule “If in doubt, toss it out”
A decade or so ago, there was a chocolate sauce recipe floating around in Northern WI, many people were sickened by this chocolate sauce due to C. Botulinum contamination because people were storing it in canning jars that were not properly heat processed. Many thought the sugar content would negate any danger, I read the article and I was actually quite surprised. Then there was another incident with a restauranteur who used leftover baked potatoes to make a potato salad, she left them wrapped in foil, and on the counter overnight to cool, they sickened a bunch of people, luckily none had died.
Honey is allegedly loaded with C. Botulinum, but it typically only affects newborns and real young kids without fully developed immune systems.
Maybe it is possible to heat your strained oil to 400 degrees, and do not seal the container to negate any issues, but I personally would not chance it.