Of squash and men.
As of this writing, I have the delightful problem of having almost too much summer squash. Accordingly, this morning’s chore was to put together a squash-and-tomato casserole in the Crock Pot®. Where it is simmering away right now.
Which got me thinking about my lifelong Crock Pot journey. And all the very-nearly-useless things I’ve figured out about Crock Pots along the way. Which I shall now pass along.
And that summer squash? I have that because my parthenocarpic squash experiment (Post G22-013, Post G22-050) is now starting to pay off. Recall that this year I grew summer squash under insect-proof netting, trying to keep the squash vine borer (Post G27) from killing them, without insecticides.
At some point (above), I lost faith, owing to the tiny squash shown above. (Plus, the plants were getting too big for the enclosure). I took off the netting a few weeks ago.
That said, the netting seems to have worked. I had it on during the worst of the vine borer season. And while I’ve seen an occasional borer since, they have been rare. All my squash plants are alive, but (by report) my next-door-neighbor lost all of his to squash vine borer damage. That’s not a proper, controlled experiment, but it’s pretty close.
After taking the netting off, I started to get full-sized squash instead of the runts pictured above. I don’t know whether these have been fertilized, or whether the parthenocarpic squash just needed a bit of time to get going. All I know is, I’ve Got Squash! No spraying needed.
Define your terms.
Once upon a time, I wouldn’t have to tell anyone what a crock pot was. But in the modern era, with its ceaseless proliferation of small kitchen appliances, I now have clarify what I mean by a crock pot.
A crock pot (or Crock Pot®, Crockpot Crock-Pot®, crock-pot, or even crockpot) is a general-purpose slow cooker. It combines a low-wattage electrical heating element with a lidded heat-proof food container. The heating element raises the temperature of the food and cooks it over the course of several hours.
I have to define it because the advent of the instant pot and the expansion of Crock Pot® products have blurred some formerly clear lines. An instant pot is primarily an electric pressure cooker, that is, a device for cooking food rapidly, under pressure. But that device can be used at lower heat, without pressure, turning it into a slow cooker (among other things). To cloud the broth further, Crock-Pot brand expanded their offerings, leading to that most oxymoronic of appliances, the Crock Pot® pressure cooker. Which, to a person of my generation, translates to slow cooker fast cooker. It has gotten to the point where you will see seemingly serious websites taking the time to explain the difference between a crock pot and a pressure cooker (reference, reference).
None of the above should be confused with an electric rice cooker, electric vegetable steamer, or a sous vide cooker. An electric rice cooker shuts off automatically when the temperature of the food being cooked exceeds the boiling point of water. (Thus it won’t scorch the rice once all the water has been absorbed). A vegetable steamer simply boils water and uses the resulting steam to cook whatever is placed in it. A sous vide cooker is typically an electric immersion heater with temperature control and circulating pump, used to cook food in a hot water bath kept well below the boiling point of water.
Finally, if that’s not confusing enough, slow cookers are faster now. But they’re still called slow cookers. The advent of electronic controls means that manufacturers can up the wattage of slow cookers. And they have done so. I’ll address that in excruciating detail in a later section.
A brief history of the Crock Pot®
Above: A Crock Pot Model 3150, with removable crock and glass lid, circa 1984, from Clickamericana.com. This is the model — right down to the original paint — that my casserole is cooking in right now.
Let’s start at the very beginning. The idea of slow-cooking food, at a low temperature, is truly ancient. It was a common practice in many times and places, including 19th and early 20th century America.
Source: USDA.gov
But these methods, by and large, consisted of heating the food up in some traditional fashion, then placing the food in a super-insulated container. The residual heat cooks the food over the course of several hours.
Even now, such devices are common in Japan, where “thermal cooker” seems to be the most common term for them (e.g., this one on Amazon.) Heat your food to boiling, place it in (effectively) a giant Thermos, and let it cook. Less developed nations achieve the same effect using a “haybox” cooker. As did the U.S., about a century ago. There is even (somewhere, I can’t find the reference) a commercial product that’s more-or-less an insulation-filled bag that does the same thing as a haybox cooker.
By contrast, what I’m talking about here is the Crock Pot. That is, a compact, electrically heated appliance, that, once loaded with uncooked food, cooks that food slowly and at relatively low temperature. It lacks the bulk of a haybox or similar setup, and is designed from the start to fit into the modern kitchen. And it, itself, is the cooker, not some auxiliary appliance.
You can turn to no less an authority than the Smithsonian Institution for a brief history of the Crock Pot. And for a nice selection of vintage Crock Pot ads, see ClickAmericana.
The appliance known as the Crock Pot was launched in 1971. It was derived from an earlier, smaller device marketed solely as a bean cooker. The original patent dates to 1940. The patent on the crock pot with removable crock was granted in 1974.
For a lot of reasons, it was an outstanding success, selling 17 million units between 1971 and 1976 (per ads on Clickamericana.com). Sales were driven in part by the mass entry of women into the workforce. It was viewed as a way to have a hot home-cooked meal ready when everybody got home from work. Prep the meal the night before or morning of, turn on the Crock Pot in the morning, and it would be done by suppertime. It was also touted as an energy-efficient way to cook, important in the wake of the 1973 Arab Oil Embargo and the resulting American energy crises of the 1970s.
For the first years of its life, the Crock Pot was only made with a non-removable stoneware crock (per Wikipedia). Only later did the first truly modern Crock Pot emerge, with patented removable crock. The patent was granted in 1974, but it appears that the first Crock-Pots with removable crocks were first sold in 1976. (Per Clickamericana cited above.)
For years, Crock-Pot continued to offer the removable and non-removable crocks side-by-side. Which seems a bit odd in retrospect. But that’s clearly documented in their ads from the time. Here’s a 1976 ad, with the introduction of the removable crocks.
Source: Clickamericana.com, annotation in green is mine.
Anyone who has ever owned one will tell you, a slow cooker with non-removable crock is damned inconvenient to clean. My wife, for example, will only use the kind with the removable crock. She is not alone. “Crock Pot Liners” are the makeshift aftermarket solution to the hassle of cleaning fixed-crock Crock Pots. Those plastic bags keep the food from contacting the crock, and cleanup means tossing the plastic bag out.
I don’t believe that Rival now offers any models with non-removable crock. But based on the comments on Amazon, they continued to offer one as late as 2020. For sure, I see crock pots with non-removable crocks in the thrift shops all the time.
Source: Amazon
If you’ve ever wondered why anybody would want one with a non-removable crock, they do have two advantages. With the non-removable crock, the electric heating element was bonded directly to the ceramic crock. By contrast, with the removable crock, the heating element is contained within the hollow metal shell in which the crock sits. The non-removable crock design uses less electricity, and the exterior of the crock pot stays cooler.
Below, contrast the stickers from three 3.5 quart Crock Pots. The top two are earlier and later versions of the model 3100, with non-removable crock, taken from Ebay ads. The bottom one is the model 3150, with removable crock, taken from my kitchen. On “low” — where most of your cooking should be done — the removable crock version uses about 80 percent more electricity than the non-removable design.
Finally, I could not discuss Crock Pot history without some commentary on how unbelievably inexpensive slow cookers have become. A name-brand Crock Pot costs about as much today as it did in 1971. I don’t mean “inflation-adjusted”. I mean the literal count of dollars is the same, 50 years later.
Per this site, the original 1971 MSRP of the Crock-Pot was $25. That’s roughly a $200 appliance today.
Source: Top from NPR station KCUR, bottom from the US BLS inflation calculator.
Here are two Crock-Pot brand slow cookers, currently offered for sale on Amazon. Admittedly, they have none of the modern bells and whistles. These are very nearly identical in functionality to the original 1971 Crock Pot (plus or minus the removable crock). You can get the smaller model for less than half what the original Crock-Pot cost in 1971.
Source: Amazon
The three-quart, three-heat-setting model costs just $5 more than the original Crock-Pot did in 1971.
Source: Amazon.
Two crock pot crocks.
Modern slow cookers are really not all that different in design from the original. Most seem to use relatively lower-powered heating elements. All have a relatively tight-sealing lid, to retain moisture as the food cooks. Nearly all lack any sort of thermal insulation, just like the original Crock Pot (except for the few marketed as having “cool touch” exteriors.)
The main change in modern slow cookers is in the electronic controls, and (typically) the modestly higher wattage of the heating elements this allows. The advent of cheap electronic controls means that modern slow cookers can operate (initially) at somewhat higher wattages than an old-style manual crock-pot like mine.
Aside for the true Crock Pot nerds. There is a persistent rumor or assertion among older Crock Pot aficionados that modern crock pots cook too fast, compared to older ones. This rumor predates the advent of electronic controls. It is always ascribed to some ill-specified government regulations that required slow cooker manufacturers to increase cooking temperatures, as a matter of food safety. And, while I have found internet chatter suggesting that some inferior brands do seem to cook too fast, to date I have found zero evidence to support the “government regulation” theory that older crock pots were slower crock pots. To the contrary, for Crock Pot® itself, the wattage on the labels above (for fixed and removable crock-pot models) suggests that the cooking performance of the Crock Pot® should have been more-or-less the same since its inception in 1971. End of aside.
Old-style crock pots had to walk a fine line between cooking the food too slowly (and so allowing bacteria to grow) and cooking it too fast (and so allowing it to boil dry and burn). They had to do that solely by a manual temperature adjustment knob. Ideally, whatever setting you use will get the food up to an extremely slow simmer — just below boiling. And it will do that without keeping the food at lower temperatures that speed the growth of bacteria for an excessively long period.
In theory, the instructions were to start on “high” to get the food up to a safe temperature, then turn down to low to finish the cooking. But in practice, people typically set the knob and let the cooker run. So, to walk that fine line, you really couldn’t use too little wattage on low, or to high a wattage on high. The result was generally a slow cooker that was, in fact, pretty slow. By design. If it cooked faster, it would end up overcooking the food. Here’s the observed wattage on mine, for today’s casserole. That’s 130 watts on low, 202 on high.
Here’s the label with the nominal wattage, for the same appliance. The measured wattage is still well within tolerances for the nominal 135/210 wattage shown on the label. Close to 40 years after this was made.
If you look at modern slow cookers of roughly the same size as my ancient 3.5 quart Crock Pot, you’ll typically see wattages in the 350 to 500 watt range for the highest setting. It’s not as if the laws of physics have changed. They can offer those higher wattages only because modern slow cookers will automatically shift to lower heat settings, either via a crude timer, or by actually monitoring the temperature of the food.
In short, the classic Crock Pot was more-or-less a one-speed device. Sure, it had high and low settings, but that was more or less optional. Modern slow cookers come with an automatic transmission, so to speak. That gives them quicker acceleration (faster temperature rise) at the start, but they automatically shift when it gets to the point where it just needs to coast along.
That said, you will see two things said about slow cookers that seem to get repeated on virtually every slow-cooking website. Near as I can tell, these date back to the ancient past of slow cookers. And, near as I can tell, they have never been right. They weren’t right for older models. They aren’t right for modern models.
Crock-pot crock 1: Never lift the lid while the food is cooking.
Go on any website devoted to slow cooking, and they’ll tell you never to lift the lid of the crockpot while it is cooking. Oh, that will drop the temperature 10 (or 15 or 20) degrees, and set back your cooking time by 20 (or 25 or 30) minutes.
If either of those things were true, the stuff I cook in my crock pot would never finish cooking. Because I lift the lid all the time. To stir, to check the food. Sometimes, if things are going well, just to get a good whiff of what’s cooking. In short, I fiddle with the contents of my Crock Pot all day long. I don’t leave the lid off — that really is a mistake. But I take it off frequently over the course of the cook.
If you think about it for even the shortest amount of time, you realize that this standard advice can’t possibly be correct. By weight, the contents of the crock pot is probably 99.9% solids and liquids (and crockery and steel casing), and 0.1% steam and air. When you open the lid, you let the steam out. But that’s all you do. You replace that steam with room-temperature air. Opening the lid for 15 seconds sure can’t chill down the liquids and solids by 20 degrees (F).
So let’s do a little math, eh?
How much steam sits in the top of a filled Crock Pot? The interior of my Crock Pot is a cylinder roughly 7″ across. Typically, I’ll fill it to within an inch of the top. But the lid is kind of dome-shaped. So, best guess, let me generously call it roughly 75 cubic inches of steam in there. Or, roughly 0.05 cubic feet of steam.
OK, how much energy is lost when I lose that 0.05 cubic feet of steam? Looking a few things up, a pound of water, converted to steam, embodies just about 1000 British Thermal Units (BTUs) of heat, and will occupy just about 30 cubic feet of space if not pressurized.
Accordingly, the steam at the top of my Crock Pot embodies (1000 BTU x (1/30) x .05 =) 1.5 BTUs of heat. I lose 1.5 BTUs every time I lift the lid of the crock pot. Oh, the humanity.
Just FYI, a BTU is about as much heat as you get by burning a kitchen match.
One watt-hour equals about 3.4 BTUs of heat. So I need to burn roughly half a watt-hour of electricity to replace the heat lost with that steam. On high (200 watts), it should take my ancient and venerable Crock Pot a whopping nine seconds to replace the heat lost when I opened the lid and let out the steam.
If you still don’t get it, compare that 1.5 BTUs of heat in the steam to the amount of heat in three quarts of water at 212 F. That’s six pounds of water, raised 142 degrees above room temperature, or about 850 BTUs. Of the heat energy inside the crock, literally 99.8% of it is in the contents, and the remaining 0.2% is in the steam above the contents.
There are probably some caveats, but that’s the gist of it. Take off the lid of the running crock pot to stir it, and the consequences are an immeasurably small drop in the temperature of the contents, and a roughly nine second delay in the total cooking time.
Crock-pot crock #2: Crock pots are the most environmentally friendly way to cook.
Well, no. Just no. No they’re not.
They aren’t terrible. Near as I can tell, they are reasonably energy efficient. For sure, you can certainly find more inefficient ways to cook. Everybody compares them to (e.g.) an electric oven, which is in fact an inefficient device for slow cooking.
But in the universe of modern cooking technology, at the typical U.S. electrical generation mix, crock pots aren’t really very environmentally friendly, in terms of their carbon footprint. They aren’t terrible. But even excluding esoteric methods like solar ovens, they aren’t the best way to reduce your carbon footprint.
The reason is that they use resistance electric heating. And for every BTU that they consume out of the wall socket, chances are your utility burned two or three times that much energy in fossil fuels, to generate the electricity. Secondarily, they leak heat out the sides, and so they themselves are far from perfectly efficient devices.
Let me do a quick comparison of two ways of cooking today’s squash casserole. First, as cooked, in my Crock Pot. And then, in what I view as the most efficient conventional cooking method, a pressure cooker.
In the crock pot, I let it cook the better part of a day. Let me call that two hours on high (200 watts), and five hours on low (130 watts), which I will simply round down to 1 kilowatt-hour of electricity. Or about 3400 BTUs of energy.
In the Commonwealth of Virginia, that generates something like 0.65 pounds of C02. And for that electricity, I will pay something like 12 cents. So it’s cheap enough, for sure. And not a big environmental deal no matter how you slice it.
In a pressure cooker, looking across several internet sources for times, and adjusting for the use of a slow release, it would only have taken about three minutes at pressure to cook the squash and carrots in the casserole. Really, virtually all the energy use would be in bringing the contents of the pot up to the 250F operating temperature of the pressure cooker.
The six pounds of casserole should have taken roughly 1000 BTUs to come up to the 250F operating temperature of the pressure cooker. A gas stove is about 40 percent efficient. And so, I probably burned (1000/0.40 = ) 2500 BTUs’ worth of natural gas. Add a bit more for keeping it at temperature, and it’s fair to say that the pressure cooker would have used about 3000 BTUs’ worth of natural gas.
So far, so good. The Crock Pot used just slightly more direct energy than the gas stove and pressure cooker. But recall that the electrical energy was largely generated by burning fossil fuels — typically at less than 50% conversion of fossil fuel energy to electrical energy.
So now let me do the carbon footprint. A therm of natural gas is 100,000 BTUs and will produce about 12 pounds of C02 when burned. Thus, my 3000 BTU’s worth of natural gas would have produced (12 lbs x 3000/100,000 = ) 0.36 pounds of C02.
Cooking this in a pressure cooker would have had roughly half the carbon footprint of cooking it in the Crock Pot. Given the carbon intensity of Virginia’s grid, at present. The direct energy use was surprisingly similar. But electricity through the grid generated roughly twice as much C02 as heating something on a 40-percent efficient gas stove.
On the off chance that you’ve been following along, you might say, wait that makes no sense. How can a 40% efficient gas stove be that much more efficient than the grid.
The answer is that the Crock Pot itself is not 100% efficient. A lot of the energy that goes into the Crock Pot simply goes to heating the metal casing, which rises to about 150F with the Crock Pot set on low. So it’s the combined inefficiency of electrical generation plus the inefficiency of the Crock Pot itself that results in the significantly higher carbon footprint of the Crock Pot.
My final question is, why are Crock Pots almost always uninsulated? And I mean, totally uninsulated.
If you take one apart — as one does, from time to time — you’ll see wire, metal, maybe some bits of ceramic, and that’s it. Other than an air gap, there is zero insulation. There are, as noted above, just a handful of cool-touch hot pots. These thermally insulate the exterior shell from the interior heating element, keeping the exterior shell cool.
My best guess is that this is mostly a holdover from the days before modern electronic controls. A well-insulated slow cooker would require very little electricity to maintain temperature. (It would operate more like the Japanese thermal cooker discussed briefly earlier). But for old-school on/off slow cookers, that would mean that you’d have to heat it up with that same small amount of power, which would probably lead to an unacceptably slow (and unsanitary) rate of warming. So that, in the old days, an insulated hot pot with a simple on-off control simply would not have worked. It literally has to shed heat, once at temperature, in order to be able to raise the contents to cooking temperature in an acceptable amount of time.
In other words, the lack of insulation is a feature, not a bug, on an old-style manually-switched (off/low/high) slow cooker.
Why modern slow cookers remain uninsulated, I cannot fathom. These days, you could just tell the electronics to turn down the heat once you reached cooking temperature. And yet, almost no slow cookers have insulation.
Perhaps it’s due to the cost. At the current low price point for slow cookers, I imagine that every corner that can be cut will be cut..
Or perhaps the entire Crock Pot community had simply ceded that ground to the new kid on the block, the instant pot. Unlike Crock Pots, instant pots are almost always insulated. If I were buying my appliances new, today, instead of using the ones I bought decades ago, I’d probably be right there with the rest of America, buying an instant pot.
I guess that’s heresy for a true Crock Pot user. But you have to let the facts lead where they may. And the fact is, slow cookers are still being built like its 1971.
Well, except no longer made in America. And with electronics that are almost destined to fail. But the basics are the same. It’s still a low-wattage resistance heating element, encircling a cooking vessel, inside an uninsulated metal shell. It’s the last part that confuses me.
