Slow cookers

Transfer that logic to a conventional oven. Most food has a high water content so liquid boiling at 100C is normal. But, would you expect a casserole put in the oven set at 100C to cook in the same time as the same casserole put in an oven set at 180C?

And Low isn't 100deg, it's more like 75deg.

Slow cookers are under 100, often around 80-85 I think.

Hence the advice not to use uncooked kidney beans, among other things - not that I had any trouble before reading that!

Most food cooks properly at about 60C, that’s the temp at which complex molecules are degraded, but it’s quicker at higher temps. Some molecules need a boil though like kidney bean toxins!

(Open to correction on all that, it’s just my vaguely held understanding.)

And Low isn’t 100deg, it’s more like 75deg.

Yes, I forgot that bit.

But if it’s 75 deg, why does the cooking liquid come to the boil?

I assumed low and high were just different power settings.

@ratherbeintobago - you're not missing something. Low just takes longer to come to the boil.

All that slow cookers are, are well insulated pots with a relatively low energy source.

Just found this.....

WHAT TEMPERATURE IS A SLOW COOKER?
The temperature settings on a slow cooker usually range from low to high. The low setting generally maintains a temperature around 190°F (87°C), while the high setting reaches approximately 300°F (149°C). The slow, even cooking at these temperatures contributes to tender meats and flavours infused into dishes..

So no, if that's right, you are missing something - on this manufacturer at least the low setting should never boil/simmer but the high should. The food in the pot on the two settings will reach different maximum temperatures during the cook cycles which obviously impacts cooking time.

Will check out (for science!) On mine when in use later in the week.

Any temperature value given is just an estimate, energy is the variable surely, on 'Low' it's pumping fewer watts into the pot and it's contents than on 'high'.

With less energy going in it's going to take longer to heat things up and depending on how much food and liquid you put in it there's a variable amount of material to get to some sort of equilibrium (along with that main big ol' thermal mass in the ceramic pot) put less food into the pot it's going to heat faster and get hotter for the same wattage input.

I don't know if there are different thermal cut-off values for high/low settings (say two circuits tied to the switch with different thermistors in) but that might be a rudimentary control method some of them employ also to prevent it running away(?)

If you want it to heat up faster, pre-heat it empty on 'high', chuck stuff in then set to low. Then again there is a reason they're called "slow cookers".

Any temperature value given is just an estimate, energy is the variable surely, on ‘Low’ it’s pumping fewer watts into the pot and it’s contents than on ‘high’.

No, listen carefully and you can hear a relay clicking on and off. Like a room heater the element won't output variable temperatures - it'll be on or off. Different settings (low to high) will trigger the relay at different temperatures. No idea where the thermistor is mind - presumably bonded to the aluminium outer shell that the actual dish sits in.

My slow cooker does bubble a little bit around the edges but I assume the bulk of the contents aren't really that close to 100C, it may get slightly hotter at some edges adjacent to the heating element. Suppose I should try a thermometer.

Saucepans of thick stew etc on a modest heat aren't always 100C throughout either, for that matter.

I think contrary to what convert says, my slow cooker has three different settings for input power rather than a thermostat. But I'm not sure.

I think contrary to what convert says, my slow cooker has three different settings for input power rather than a thermostat. But I’m not sure.

"For science" you understand , and absolutely nothing to do with "winning and internet discussion" 🤭, I've tested my Murphy Richards slow cooker with a plug in energy monitor. I can confirm that at all 3 settings it draws 158watts when the internal thermostat is calling for heat. I.E. the element is just on or off - the only difference between the settings being the temperature the relay switches on/off the supply to the element. Other bands/models might operate differently but to be honest I doubt it as it's how pretty much every cheap electrical unit I've pulled apart is designed.

Thanks, I'm happy to be corrected. I found this on a quick web search but mine is a cheap Morphy Richards so likely to be similar to yours.

https://cooking.stackexchange.com/questions/18867/what-temperature-should-a-crock-pot-slow-cooker-cook-at

Give him/her a kick up the backside and tell them to hurry up as you're hungry.