NCA's recommendation applies to a wholly different context and ignores relevant considerations of the instant situation. You're trying to apply a single-criterion optimization function to a problem that calls for multi-criterion optimization function. Here, we are not merely talking about brewing coffee. We are talking about a business model based on brewing coffee and then serving it to customers in "easily crushed" containers who are driving in their cars. Whatever the appropriate brewing temperature happens to be in that context, it is not given by NCA's recommendation.
Whatever the appropriate brewing temperature happens to be in that context, it is not given by NCA's recommendation.
The temperature at which the flavors and oils that make up coffee are optimally extracted from ground beans does not change based on the business model of the people selling it.
That's true, but the fact that there is an approximate ideal water temperature for coffee brewing has no bearing on what appropriate storage and serving temperatures might be.
Assume for a minute that they were holding at 170F (chosen because it's a middle ground between 160 and 180, common hot beverage holding temps from [1]).
Even at that lower temperature, Stella would still have sustained third degree burns in under one second [2]. Even if you're generous and take 20 degrees off to account for cooling between the time of pouring and the time of spilling, that's only one extra second's difference to get second/third degree burned. Given that her burns were exacerbated by her clothing trapping the hot liquid next to her skin, that isn't enough to have made a difference in the outcome.
The conclusion is clear. Any reasonable hot holding temperature will result in serious burns if you get the liquid on you soon after purchase.
That's presumably why the jury found her partially at fault. However, increasing the temperature above that greatly increases the severity of the burns, which is why McDonald's was also partially at fault because they served the coffee at a higher temperature so her burns were more severe than they would have been if it had been served at a normal temperature.
...did you just miss where I explained that any reasonable hot holding temperature would result in second or third degree burns in one or two seconds? If you've got clothing trapping burning liquid next to your skin, the extra 20 degrees temperature ceases to be a factor - you're getting third degree burns either way.
