Reheating question: temperature gradient figures?

In the Sous Vide Recipes Forum
Are there any data about how long it takes food from the fridge to heat to a percentage of the applied temperature in the bath?

So far as I have seen, to reheat sous vice food sous vide, you set the bath temp to what you cooked at, so as to not overcook, and then use the original time, sans tenderising and pasteurisation, for a simple warming.

It occurred to me that nearly all meat is acceptable to eat at a temperature quite a bit lower than the actual cook temp: it just needs to be warm to bring out the juices and wake up the meat. It would save a bit of time (possibly quite a bit, because the temp delta speed is anti-log or like that...asymptotic) if you used the original temp to heat the food, but were happy to settle for a lower serving temp.

So it seems to me of use if you could know a time at which the food reaches some percentage of the bath temp, because it seems that the time to _reach_ bath temp is not much affected by the bath temp, just by thickness....that makes sense to me; higher "temperature pressure", faster temp climb. But I can't find anything about this, graph or figures.

So. I cook at 57 C, for however long I need to get the desired effect. I then refrigerate. Later I want to heat for eating. Say I am happy to eat at 40 C. In a 57 C bath, given a thickness, how long would it take?

Any info greatly appreciated.

Nick


5 Replies So Far

OK. Nobody.

I have worked on this. Douglas Baldwin does provide a graph of 27 mm fish in a 55 Deg bath and its heating curve. I realise that meat and fish are different, but I feel that the _curve_ from fridge to bath will be very similar. Based on that I have set up some figures.
I haven't seen much about this. I don't think the temperature affects the heating all that much and the real small range we are talking about, i.e. it'll heat to 55C about as fast as 50C/45C/etc. I also think that anything below about 51C is going to taste pretty cold to you. I think the time saving would be in the range of a few minutes and would result in a significantly cooler and less flavorful meal.
Thanks for the reply Jason.

I want to taste food at different temps when reheating, but I take your point that there is a minimum acceptable food temperature.

If you see the curve in Douglas Baldwin's Practical Guide, if you use a a 55C bath to heat food, there is a significant time saving if you heat to a temp below the bath temp. As you would know, to take it to 1 Deg C below bath rather than 0.5 Deg C below saves 13% of the time and it falls away faster and faster the further you go down from bath temperature.

From my looking at it so far, just off the graph, it seems that if I have say, a 58 Deg bath and want 45 deg reheat, it could take only 40% of the time that it takes to get up to full bath temp. In fact I have applied that to frozen food and found my food was considerably hotter than I expected after partial reheating for the time I had calculated.
Sorry to bang on.
My pressure here for me is to get over the sous vide time barrier for common acceptance: people are "time poor" and the times for sous vide are are longish. If we can encourage the idea that reheating already sous vided food, using sous vide, is faster than cooking using sous vide, then the idea of cook/cool/fridge(freeze) can allow the "time poor" to do large cooks and then use them to reheat. In particular, there is a common idea that meat that needs no tenderisation time has no advantage by pre-cooking. But if simply reheating to an acceptable eating temp will drastically shorten tomorrow night's meal prep...

Tonight I tried some steak that was 40 C (yeah ho hum) and some that was 45 C. 45 C was quite nice and with a hot gravy, or served with nice hot sides, would be fine....with a salad???? I shall keep testing and reporting.
BTW I have no reason to promote sous vide apart from the fact that I am a SV tragic and for a reason: it gives amazing results; reproducible. Just for the record. Not affiliated with anyone.

Nick


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