Resurrecting the California Cooler




About: By day I'm a mechanical engineer at a university laboratory. In my free time, I do my own projects.

Coastal Northern California is blessed with a very moderate climate, generally on the cool side, especially at night. Before the refrigerator became common in households, denizens of this region took advantage of the cool weather by storing perishable foods in a special kitchen cabinet that brought in air from the outside -  the "California Cooler."

When the refrigerator came along, it seems that, over time, the vents were boarded up and the California Cooler was all but forgotten. Today, if you walk the streets of my hometown, Berkeley, where most of the houses were built in the 1920's, you will see many homes, and even apartment buildings, with the exterior vestiges of these vents.

My house is such a house. When we decided to remodel our kitchen in early 2009, I came up with the idea of opening the vents and bringing our California Cooler back to life. What better way to conserve energy in this age of green thinking than to keep foods cool with outside air? This is the story of the resurrection of a California Cooler.

Step 1: History of the California Cooler

Most of the information I have found on the Web about California Coolers consists of blogs dealing with kitchen remodeling.. This blog ( has some interesting information. The author says that the California Cooler came into existence in 1910, not in the 19th century as I would have thought. I may have to go to the library to find out more about the history. Below are a few more interesting links that I've found.

In this link someone is remodeling their kitchen and debating whether or not to keep the CA Cooler

Below is a gallery of California Cooler photos that I shot in South and West Berkeley, actually photos of the exterior vents which, presumably, are all boarded up. They are VERY common around here and the majority of them seem to be floor-to-ceiling pantries. Our single, large vent seems to be very unusual.

Step 2: The Basic Idea

When I started this project, what I had in mind was the following:

A. Re-open the wall vents and have a special cabinet designed to function as a California Cooler.
B. Add insulation to the cabinet.
C. Make the vents louvered so they could be closed and opened.
D. Keep an indoor-outdoor thermometer probe in the cabinet to monitor the temperature.
E. Purchase a much smaller refrigerator for our new kitchen to go along with the CA cooler with the intent of saving electricity. I have known for some time that some foods that are commonly kept in the fridge don't need to be kept there, such as eggs and butter, and others, like tomatoes, may even be harmed by refrigeration.

Step 3: Materials We Used

Cabinet: A custom cabinet 44 x 21 x 12 inches inside

Wall Insulation: RMax rigid polyurethane insulation 1-inch thick (photo below)

Weather Stripping:

Interior Lining: 1/2 inch maple plywood

Shelves: Wire Cloth held up with standard 5 mm shelve pegs

Thermometer: Oregon Scientific Wired Indoor-Outdoor Thermometer

Step 4: How It Was Done

(See photos below for sequence)

A lot of the credit for actually making it happen goes to our kitchen re-modelers, Eric Christ of Halperin and Christ Building and Design and his nephew  Noah, as well as the cabinet maker, Jeff Ward. First, they removed our old cabinets and exposed the old vent. This was a single vent that was fairly large. Perhaps it was divided into two vents originally, but what we needed for the dimensions of the new cabinet was to seal off some of this vent and then to cut a new one up higher.

When the new cabinets arrived, they cut holes in the back for the new vents before installing the cabinet on the wall. For louvers, we used a pair of heating registers with little levers for opening and closing. After the cabinet was installed, the new vent was cut in the side of the house to match the upper cabinet hole (See Intro Photo). A strip of adhesive foam insulation was also added along the vertical edge, to prevent air exchange with the kitchen.  Soon similar pieces of insulation will be added at the top and bottom.

Next, we added insulation to the back and sides of the cabinet, and Eric made some custom pieces of wood to cover the insulation and line the cabinet. The wood and insulation in the back was given holes that matched the vents and into these holes the heating registers were mounted.

On the side walls, we drilled sets of holes for the shelf pegs. The wire cloth was cut with a grinding wheel, and then bent to the right size by a metal shop.

Finally, insulation was cut for the door. It has not yet been permanently installed (still trying to figure out how to do this), but it's put in place for most of the day, except when we are home, cooking.

For now, the thermometer probe has just been inserted through the gap at the bottom of the door, but soon we'll drill a hole in the bottom of the cabinet and mount the thermometer on the wall.

Step 5: The Results

January 5, 2011
The California cooler is now just over a year old. We are now at the coldest time of the year and it's working great. One thing that has been bugging me is that I have no way of knowing how much energy the California Cooler saves. Probably the biggest savings is that we got a smaller refrigerator when we remodeled the kitchen and then the CA Cooler could be a little savings on top of that. I've decided to collect some data that may shed a little bit of light on things. I'm going to measure the energy consumption of the fridge for the entire year, and also record the outdoor, kitchen, and cooler temperature on as many days as possible. Maybe after another year I'll have a better idea of how the cooler reduces the amount of electricity used for the refrigerator.

November 8, 2010
After that heat wave in June, we had the coolest summer in at least 30 years. During that time the California Cooler worked as well as could be expected - the temperature varied from 60-65 most of the time - we still kept eggs, peanut butter, cooking oil, carrots, parsley in there, but not butter.

In August, our "indian summer" came and we had warmer weather for the next two months. We had to completely stop using the CA Cooler during that time. It wasn't much of a problem to fit all of our food in our small fridge. Maybe next year I'll get around to trying some of the ideas appearing in the comments. The two that interest me the most are: 1. evaporative cooling a la a swamp cooler and 2. A solar powered peltier cooler.

In late October, our version of fall began and now the cooler is in the low 50s in the morning, and goes up to around 60 during the day. We've started using it again and, as the weather gets colder, we should be able to add more and more items and we should be able to use it continuously until at least next June. Then we'll see what kind of summer is served up.

June 30, 2010
We had a mini heat wave and during that time the cooler didn't work well at all (went above 70 F). Fortunately, that only lasted 2-3 days. Now we are back to our typical summer pattern: 70-75 F during the day and a low of 57-59 at night. I put in the cool thermal masses in the morning before I leave for work and close the vents. The temperature swing under these conditions is about 60 F minimum and 65-67 maximum. If I watch the weather report, I could consider putting some ice in the cooler during abnormally warm days.

May, 2010
The spring has turned cool and the CA cooler is working quite well (staying below 65 F during the day).

April 4, 2010
With the warmer spring weather, I have given up keeping the temperature below 60 F and settle for a maximum of about 65 F. However, it always goes down into the 50s at night, which is why a CA cooler can work in N. California. I am using more water for thermal mass (about 3 gallons at this point) and there are certain foods that we probably won't store during the warmer months, like strawberries.

February 17, 2010
Our short Bay Area winter is coming to an end. We had a week of temperatures in the mid 60s and the CA Cooler went as high as 65 F one day. I would like to keep it below 60 F if possible, and this will become a challenge as the year progresses. I have increased the amount of cool thermal mass (bottles of water) that I put inside the cabinet every morning and remove in the evening. On a couple of days I also tried putting in 2-3 ice gel packs from our freezer and closing the vents in the morning. That worked just fine but, of course, it takes electricity to freeze those packs.

Another idea that I got from a reader's comments is to try putting a damp cloth inside, in the hopes of getting evaporative cooling. A couple of times I hung a damp cloth from one of the shelves, but, it didn't seem to have worked I will experiment some more with the location of the damp rags.

February 10, 2010
The CA Cooler is now pretty much finished. The door has built-in insulation and also weather stripping at the top and bottom edges.

January 10, 2009
We were away on vacation for 2 weeks and the CA Cooler stayed below 60 F the entire time.

December 10, 2009
We have been having unusually cold weather, with temperatures in the 30s at night. I have seen the temperature difference between the kitchen and the cooler as high as 23 degrees F. The coldest I have seen the cooler get is 39 F. I then decided to close the vents on the coldest nights, because I didn't want it to get so cold.

December 3, 2009
We have been using the CC for about three weeks and we love it! For the first two weeks, we didn't have any insulation on the door and the temperature inside the cooler was between six and ten degrees Fahrenheit colder than the kitchen temperature. Typically, the cooler has gone down to the upper forties at night and up to the high 50s or low 60s during the day.

We have been keeping eggs, butter, oils, peanut butter, apples, onions, tomatoes, broccoli, cilantro, parsley and strawberries inside it. It turns out that we keep so much food in the cooler that there is plenty of room in the small fridge for the rest. It's not even an issue - our old fridge was always more crowded with food than this one is.

I also keep a gallon bottle of water and two quart bottles in the top shelves to act as thermal mass in order to keep the temperature lower during the day. I can increase this effect by leaving those bottles out at night, so they get as cold as possible.

Last week, I added a layer of insulation behind the door. It's still not permanently attached to the door, so we keep it on overnight and when we're gone during the day. Now, the temperature difference between the cooler and the kitchen is between ten and seventeen degrees F, which is excellent. The weather lately has seen temperatures in the mid 40's at night and in the upper 50's during the day. The cooler goes down to around 46-50 F at night, and up to 57-62 during the day.

summer, 2009
We committed ourselves to buying a very small refrigerator at the beginning of our kitchen remodel. This refrigerator would have 10.3 cubic feet of volume, compared to the 16.6 cubic feet of our old fridge. As the kitchen remodel progressed, we sometimes got cold feet. "What will we do if the California Cooler doesn't work and we have to fit all of our food in that tiny fridge?"

Step 6: Is There a Future for the California Cooler?

Update October 2014

We have had the CA cooler for several years now. We still keep the same types of items in it - butter, tomatoes, eggs, some oils, peanut butter. Overall, I would say that it's not worth it for someone remodeling their old house to spend a lot of money resurrecting their CA Cooler, nor to add them to new houses. I think the main lesson we have learned is we can get by with a smaller refrigerator, and I suspect that most households could do the same. That would be a great energy saver, but the trend for a long time has been for households to buy ever larger fridges.


A couple of mornings ago as I road my bike to work, I decide to see if I could spot any California Cooler vents on houses. Not surprisingly, I found a bunch. They are very common in the flats of Berkeley, not just on single family houses, but on old apartment buildings. It seems like the majority of them are for floor-to-ceiling pantries. Yesterday, I surprised myself even more by counting that more than half the houses on my block have them, as well as one apartment building (I will definitely be asking my neighbors if I can take a peak inside their kitchens to see what has become of their California Coolers!).

I can imagine that people in the 1930s were excited to get their new-fangled refrigerators and that continuing to use the primitive California Cooler would have seemed ridiculous. But we live in a different era now, one in which using renewable energy is preferable. The cool air that we have along the California coast comes to us free of charge via winds and currents of the Pacific Ocean.

I have a fantasy that others will resurrect their California Coolers as we have done. But, from a green perspective, does it really make sense to do this? I think that our method of storing some foods in the California Cooler, and others in the refrigerator will definitely use less energy that we did before. According to a Federal Trade Commission Document our old refrigerator used 464 kilowatt hours and our new one 309 kWh per year, for an annual savings of 155 kWh. That's about enough energy to run our entire household for 17 days. Not bad for a cabinet with two vents in it!

But, when I think about how much it cost to make the cooler, it's actually kind of embarrassing. I think it cost at least as much as a brand new refrigerator! Of course, most of the expense was in labor, and we also chose to use pretty expensive materials because we wanted it to look really nice.One choice that could have been made differently was the use of polyurethane insulation. This is a non-recyclable petroleum product. If I were to do it again, I might choose some other type of insulation, such as recycled denim. However, I'm not sure that other types of insulation would do such a good job, or work for a long time with moisture present.

If you live in an old house that has a boarded up California Cooler, would you consider doing something like this? I'd love to hear comments from you. If you are a builder, would you consider putting a California Cooler in a new house?

Also, out of curiosity, I'd be interested to hear from people in other cities where houses were built between 1900 and 1930. How common are California Coolers there?

I actually think that resurrecting the California Cooler is a subset of a larger energy saving idea - to use outdoor air to aid refrigeration. Under certain conditions, it could be more efficient for a regular electric refrigerator to exchange air with the outdoors instead of the air in your kitchen. And, in certain places, during certain months, it's cold enough to use outdoor air as a freezer. Imagine if in places like Minnesota if people had the choice to operate their freezer with outside air in the winter and then use it normally in the summer. That could save a lot of energy when compared to running a freezer in the winter while heating the air inside the house for comfort. I have started doing little things to make our fridge not work as hard. For example, when I cook a big pot of soup, I let it cool down to room temperature until putting it in the fridge. Sometimes I'll leave something out overnight (if it doesn't have a smell that would attract animals) and then put it in the fridge in the morning, shaving off the amount of cooling the fridge needs to do on that item.



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    165 Discussions


    8 years ago on Introduction

    OMG - just read this:

    "I have started doing little things to make our fridge not work as hard. For example, when I cook a big pot of soup, I let it cool down to room temperature until putting it in the fridge. Sometimes I'll leave something out overnight (if it doesn't have a smell that would attract animals) and then put it in the fridge in the morning, shaving off the amount of cooling the fridge needs to do on that item."

    You understand you are playing Russian roulette with microbes by doing this right? You may end up making your fridge work less but your guts work more to expel food that has spoiled.

    Food is at high risk for spoilage if it is held at temperatures between 40 and 140F for longer than 2 hours.

    19 replies

    Reply 8 years ago on Introduction

    Absolutely Correct!!

    I am certified in the state of Connecticut as a licensed Food Handler, and what ravenwing is doing is creating the textbook perfect conditions for the creation and propagation of C. Botulinus, and Salmonella, as well. This practice is extremely hazardous!! One airborne spore, allowed to enter this food medium at temperatures between 40 degrees and 160 degrees Fahrenheit, and then sealed anaerobically, will kill your entire family, if it doesn't blind them first. If you doubt what I say, I suggest you use your little computer to research the local Public Health website in the town you live in. And she can tell every restaurant she ever worked in that the management is literally endangering the lives of every customer! That is, if you believe her claim, which I certainly do not. This is not a joke, this is a very serious, life- and death- matter!!


    Reply 8 years ago on Introduction

    There is also a big danger of heating up EVERYTHING in your fridge if you put pots of uncooled items in there, which risks spoiling ALL OF YOUR FOOD, so given the choice I generally let foods cool outside the fridge and put them in when fairly cool.

    And it's not like the hot thing you are putting straight into the fridge is going to cool to 5C immediately anyway (while it's heating everything else up!).


    Reply 8 years ago on Introduction

    In order to prevent "heating up" the entire contents of the fridge, restaurants, caterers etc., often sit a large pot of hot food in an ice bath, stirring frequently, to reduce the temperature quickly, and maintain food safety. You can find large polyethylene "coolers" in restaurant supply catalogs which are sort of like a large jar with a round bottom, not intended to be free-standing, but for suspension in a large stock pot full of hot soup. The "cooler" has a screw-top, and is filled with ice, and then dropped into the pot, cooling it rapidly! If godforbid the ice should melt, replace it with some more!

    Too many people in here putting absolutely one point of view ahead of modern, common practice. One lady wants to kill her family, and another fella says its her right to do so..... Try thinking a bit before engaging tongue, and allow for a different, maybe even safer method!


    Reply 8 years ago on Introduction

    > Too many people in here putting absolutely one point
    > of view ahead of modern, common practice.

    That's your one point of view...! And that might also make sense if this were a discussion amongst restaurateurs, but this is instructables, and most people commenting here are home owners doing home cooking.

    None of us will have "ice bath cooling apparatus", and it is unreasonable to expect any of us to have such things. They are also unnecessary for home cooking.

    I admit that sometimes, for speed, I will put a very large pot of fresh soup in a sink of cold water to cool it down more quickly before putting it in the fridge, but apart from that there is no particular danger from allowing recently-boiled soup to cool, covered, for a few hours before putting it into the fridge.

    In addition, since we are home cookers with domestic refrigerators, it is not safe to put hot items into a domestic fridge because it WILL heat up other neighbouring items for some time, some of which may have been in the fridge for a while, and some of which may get heated up several times, each night, when hot items get placed into the fridge.

    Let the fridge do its job - keeping cool things cool. Just be sensible with the rest - let food cool before you refrigerate it. And if it will cool slowly (large pots or very hot weather) or may already have a short shelf-life (items not recently boiled) then try to cool it quickly, refrigerate it promptly, and then keep track of how long things have been in your fridge!


    Reply 8 years ago on Introduction

    "In every restaurant I worked in, cooked food was ALWAYS cooled to room temp. before refrigerating it."

    "so the restaurants are required to break the surface of the soup and stir in possible pathogens during the cooling process... remember there is a human breathing right above that soup while it is being stirred... "

    "Refrigeration was a massive improvement in public health safety. Before mechanical refrigeration they use to haul enormous blocks of ice down from the Northern America and kept it insulated with straw. In the old UK structures (as in the middle ages) they had ice lockers."

    "It is slowly being discovered that our very aversion to germs and our futile fight to eradicate them from every aspect of our lives is also robbing us of our natural ability to fight off many of these germs. Our immune systems actually become stronger only with contact with various germs and our dependencies on antibiotics only leaves us less able to defend against germs and stronger and more virulent strains"

    I don't really disagree with anything being said here, on an individual basis. Treat your food anyway you wish. I can refuse to eat it if I wish. When ravenwing made the first quote above, it started getting a bit scary. Botilinus toxin DOES exist, it IS FATAL, even Al-Qaeda knows that. Ravenwing never saw the owners of every restaurant she ever worked in follow poor food-handling procedure. The majority followed safe procedure, she just wasn't paying attention, I'm sure!

    In closing, (I hope...) The chances of poisoning yourself or a whole congregation are relatively small. But there were a few people making some VERY broad statements I thought it important to refute. The long & short of it is, do what you want. Don't bother me if you get a bellyache!


    I appreciate your comment, but I think this is a debatable point. To my knowledge, I have not had food poisoning or any problems with spoiled food. I think in general people overdo it with refrigeration. When you say food is at risk for spoilage between 40 and 140 F for longer than 2 hours, that can't possibly be true as a general statement. Think about it - people bring sandwiches to work for lunch all the time and have them at room temperature for several hours. Each food needs to be treated on a case by case basis and by challenging our notions about refrigeration, we can use a little less energy for that purpose. Eggs are one of the best examples. Everyone keeps eggs in the fridge and my experience says that they do just fine at California Cooler temperatures for long periods of time.

    It is not debatable, it's science.

    Plenty of foods provide a perfect habitat for the growth of microbes between 40 and 140F.

    Below 40 and growth is slowed or halted. Above 140 they can't survive - although some newer strains of e. coli have been shown to be very heat and pressure tolerant, which is cause for concern.

    "There are two completely different families of bacteria: pathogenic bacteria, the kind that cause food borne illness, and spoilage bacteria, the kind of bacteria that cause foods to deteriorate and develop unpleasant odors, tastes, and textures.

    Pathogenic bacteria can grow rapidly in the "Danger Zone," the temperature range between 40 and 140 °F, but they do not generally affect the taste, smell, or appearance of a food. In other words, one cannot tell that a pathogen is present. "

    When you are dealing with dairy, meat and beans it is entirely foolish to disregard safe storage temperatures, whether the food is raw or cooked.

    For example, restaurants are required to take soups down to below 40 as quickly as possible before storing it in their coolers. They do this by putting the pot in a sink full of ice and water and stirring the soup until it is cool.

    I'm a serious home canner. I have a root cellar. And I have been in the restaurant business for years. So I understand there are plenty of foods that don't need refrigeration.

    However, "challenging our notions about refrigeration" is not sound advice, especially when you are coming at it from energy use biases, which have nothing to do with food safety.


    Reply 8 years ago on Introduction

    I'm a serious biologist. I have a lab, where I grow bacteria for a living. And I sez that advice like this is why our society is over-sanitized. In order for pathogens to grow in food, they have to show up in the first place. In the case of a pot of soup, if it's covered while hot that won't happen. In the case of eggs, they are already sterile little globes that do a really good job of keeping pathogens out, because that what the growing embryo needs. The restaurant business has plenty of rules that should never apply to home kitchens (are your sponges soaking in a tub of disinfectant at your house?). And canning is the process of rendering something sterile so that it can be kept totally unrefrigerated for months at a time. For perishables that will be eaten within days, there are many fewer issues.

    I love this idea! If I owned instead of rented, I'd be doing it now. As it is, my kitchen and pantry are unheated, and we keep lots of food out of the fridge. It's great! Great job, dlg!


    Reply 8 years ago on Introduction

    You can do whatever you want with your own food. I'm certainly not a zealot about cleanliness and procedures in my personal kitchen.

    But to suggest that the growth of pathogens in food is "debatable" is borderline irresponsible.

    And for a "serious biologist" to suggest that a covered pot of soup is an acceptable safeguard against pathogens is downright laughable.

    Here's a scenario for you. You make the soup. You cover it and put it on your counter to cool (which in itself is a bad idea, as you are now keeping it in the danger zone even longer by trapping in all that heat with the lid).

    A family member takes some some with a ladle and puts the ladle on the counter, where it picks up some critters. You come back in later to stir the soup with the same ladle, which inoculates your perfect growth environment (AKA "soup") with said critters.

    Maybe some bad critters will grow. Maybe something unpleasant will happen when you eat the soup, maybe not. But why take the risk? Is your bathroom that awesome a place to hang out?


    Reply 8 years ago on Introduction

    I am reading this and cannot help to think back at some things I have seen over the years.

    In 1989 I saw people selling meat in Namibia. A whole carcass, in the sun, at about 38 degrees Celsius. That is really hot. It took then 4 days to sell everything. When they grab hold of the carcass to cut a piece of, the area around it turns black because of the flies that were sitting on the meat.

    I did not buy any of that meat for obvious reasons, but it sure goes a long way in proving that modern day thinking in terms of germs and sterile environments might be a bit over the top.

    I do not say that we should leave meat out in the open, but I do think we can leave more things unrefrigerated.


    Reply 8 years ago on Introduction

    I think that America (for some reason though I probably lean more towards bad law-makers and good (that is deceitful) lobbyists) has had some things beaten into us rather than proven to us. If you take a look around aka Germany, New Zealand, and Britain, eggs are kept at room temperature in the stores where they are stacked in an isle and sold.

    I think we need to rethink our 'danger' zones and food handling methodologies. I think some maybe over regulated in order to get people to at least comply with a lessor standard that wasn't being adhered to before the more restrictive regs were put in place.


    Reply 8 years ago on Introduction

    Most of the countries you mentioned have very cool clients. I lived in various parts of the UK, and some people did put their eggs on the shelf. But the interior of our house was kept at 60F or so. Student poverty and such...

    Refrigeration was a massive improvement in public health safety. Before mechanical refrigeration they use to haul enormous blocks of ice down from the Northern America and kept it insulated with straw. In the old UK structures (as in the middle ages) they had ice lockers.

    I have no idea as to why someone would take a chance with something that is so elementally obvious.

    Food Refrigeration is ubiquitous for a reason. It allows for food to be kept safer and cheaper than non-mechanical designs. Cheap and safe. Like seatbelts. It only takes one time. The odds of being in a car accident in a lifetime are pretty good, particularly in New Zealand.

    It only takes one time for something to go seriously wrong. Bohemianism is not a fun way to die. The mechanism of death is basically the same used in various chemical weapons.


    Reply 8 years ago on Introduction

    I see... so the restaurants are required to break the surface of the soup and stir in possible pathogens during the cooling process... remember there is a human breathing right above that soup while it is being stirred... If that actually *is* a regulation, then I really must challenge it's efficacy.

    It is slowly being discovered that our very aversion to germs and our futile fight to eradicate them from every aspect of our lives is also robbing us of our natural ability to fight off many of these germs. Our immune systems actually become stronger only with contact with various germs and our dependencies on antibiotics only leaves us less able to defend against germs and stronger and more virulent strains.

    I keep my eggs in the cupboard. I thought everyone did..

    Love the idea, no houses i know in New Zealand ever had these coolers though, and I'm not about to knock a hole in my rented property :D


    Reply 8 years ago on Introduction

    I've seen a few of them in various rental properties in NZ. My father calls them a meat safe, like those camping food-storage things you hang from trees.

    I've always found those egg-holder things in the doors of fridges to be uselessly small; the eggs always fall out when you open the fridge. I've kept my eggs on the bench for years. Um. Not the same eggs the whole time, obviously. But they each last a month or so quite happily.


    Reply 8 years ago on Introduction

    Safes were commonly installed in homes in NZ in the past and were still fitted in The State houses right up through the '50s (Kawerau, Meremere, etc). Early ones were a wall mounted cupboard as previously described. The later ones had a "fly screen wire" covered vent through the floor at the bottom of a set of 3 vertical cupboards with the shelves in each made of 3'x3/4" slats with gaps.Another vent either to the outside or the roof space ensured air flow. They were used for fresh vegetable storage(and eggs). Most homes had refrigerators too. As a country kid in the 40's my mum also had a meat safe hanging out in the cooler 'tank shed' but the meat was never in there for long. However Dad was a keen deer stalker and I remember a hind quarter often hanging out there too. A chunk of meat was sliced off and the rest left there in a muslin bag (to keep flys away). He is now in his 90's so maybe we had tougher guts in those days.

    A few comments to fuel this fire. First, if the food is cooked (ie. soup) above 140F and the lid left on for that time, the microbes (ignoring heat resistant strains) are all dead. If that container is left closed before cooling into the "danger zone", the inner contents should be sanitized (not sterilized) well enough to cool outside prior to refrigeration. Second, being outside means that there is better airflow around the the container to provide quicker cooling than just sticking the item in the fridge (what most people do rather than water bath it while stiring) where there is little to no airflow unless you have an industrial fridge with an air circulating fan that runs all the time. Third, "danger zone" and all this other guide lines are overprotective by nature since there is a difference between leaving a pre-boiled pot of veggie soup covered and outside in 45F temps for a couple hours and leaving an open container of mayonaise out on your counter on a humid 80F day. All the guide lines are meant to be a suggestion for best chance of never getting a food spoilage illness. By the way, i'm a home brewer. I take a sugar rich substance and leave it at about 65-70F (sweet spot of the "danger zone" for yeast) for 6-12 hours before the yeast take hold and provide a carbon dioxide layer on the wort protecting it. Which goes back to my first point of sanitizing the contents and container and keeping a closed system.