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How to measure temperature of heated vegetables correctly with an IR thermometer

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nightfire:
Situation: I am an aspiring hobby/home chef, and my newest toy for doing also temp measurements in electronics i repair is a Fluke 62 Max+ IR thermometer.
Nice thing, and most important, has adjustable emissivity from 0.1 to 1.0

So theoretically I should be able to measure the surface temps of all my pots and pans (low emissivity, around 0.1), and be able to look for the surface temps when I put vegetables like onions and celery wit carrots in a pot to prepare as a sofrito (spelling right? non-native speaker here).

The magic temp is around 140 deg. C, the so called "Maillard temperature", when roasting processes begin to take place.


Any words of wisdom how to do good readings with an IR thermometer, and on the emissitivity values used?

PlainName:
High emissivity is better for accuracy, and I wouldn't want to be relying on something with a 0.1 value. Pots and pans are naturally reflective so you would need to be careful you're measuring the pots rather than something you can see reflected by them. A cast iron griddle seasoned black could be good.

You will hit a problem seeing the surface temperature once your food is in the pan. Even if you start off with the pan at exactly the desired temperature, when you add the food the temperature will drop. I think you might be better off with a k-type probe or similar rather than IR, although that would get in your way more. Depends on how nerdy you want to be about temperature.

nightfire:
Yes, it is only one thing to measure the surface temp of a pan or pot- a trick is to coat it with oil to get better readings, from what I have read...
I also want to know the surface temp of the veggies that are on top of the heap, which easily can be 1 inch/2.5cm thick.

Question here would be: Can I trust readings with an emissivity of 0.95, or to which value I would have to reduce?

And also yes, a K-Type probably is more accurate, but I am not nerdy (or needy yet) enough to use this.

PlainName:

--- Quote ---Can I trust readings with an emissivity of 0.95
--- End quote ---

Depends on how accurate you need to be. When it comes to veggies you could measure their temperature (before starting) with a contact thermometer and see how closely the IR agrees at 0.95 - it will probably be close enough, but if not you can adjust the emissivity to account. However, once in the pot and being cooked that could change (with fluids and stuff going everywhere). Nevertheless, it would probably still be OK for your purposes.

IMO, I hasten to add - I am not an expert at either cooking or thermometry!

Marco:

--- Quote from: nightfire on September 07, 2022, 03:53:03 pm ---And also yes, a K-Type probably is more accurate, but I am not nerdy (or needy yet) enough to use this.

--- End quote ---
Owning some probe and oven thermometers isn't very nerdy, pretty sure they are all k-type inside.

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