Mystery solved.
Well, sort of.
According to Douglas Baldwin, the rule is gathered from information in the US Food Code but not succinctly and specifically spelled out, that's why, even after MUCH searching, I wasn't able to find it previously.
Quoting Douglas Baldwin..... "the US Food Code requires that such food can only be between 41°F (5°C) and 130°F (54.4°C) for less than 4 hours (FDA, 2009, 3-501.19)".
http://www.fda.gov/Food/FoodSafety/RetailFoodProtection/FoodCode/FoodCode2009/ucm189211.htm
So, "40 to 140 in 4" to make it easy to remember and for an added margin of safety!!!
HTH
~Martin
Well, sort of.
According to Douglas Baldwin, the rule is gathered from information in the US Food Code but not succinctly and specifically spelled out, that's why, even after MUCH searching, I wasn't able to find it previously.
Quoting Douglas Baldwin..... "the US Food Code requires that such food can only be between 41°F (5°C) and 130°F (54.4°C) for less than 4 hours (FDA, 2009, 3-501.19)".
http://www.fda.gov/Food/FoodSafety/RetailFoodProtection/FoodCode/FoodCode2009/ucm189211.htm
So, "40 to 140 in 4" to make it easy to remember and for an added margin of safety!!!
HTH
~Martin