Take the tour ×  According to the USDA cooking chicken at 145ºF
(63ºC) for 13 minutes (i.e. maintaining an internal temperature
of 145ºF for that long) will bring about a "7 log10 relative
reduction of salmonella".  A recent question made me wonder
whether this can be considered safe for sous-vide applications
where it takes 4+ hours to reach 140ºF since the FDA
recommendation (which only applies to commercial kitchens) is
that once food enters the 41-135ºF zone (5-57ºC), it should be
"cooked and served" within 4 hours. The USDA rules for home
cooks are much stricter recommending that food should not remain
in the 40-140ºF (4-60ºC) zone for more than two hours.  I always
imagined that food left in this, so called, danger-zone for too
long has given bacteria time to multiply and produce enough
toxins in the food for it to become dangerous.  Another idea
occurred to me, that after four hours the bacteria count has
risen enough that a significant number of bacteria will be
present even after a 7 log10 reduction.