LEDs at Elevated Temperature

[gophert]

The temperature monitor has been proven a success.

The results the first test provided, based on one off-brand Instant Pot, aren't what we had hoped for. The maximum temperature of ~ 105°C corresponds to about 1.2 atmosphere.

We had expected about 1.5 atmosphere to reach a temperature of 111°C, which is the minimum safe temperature to can fish.

But this is just the start of the project to document whether any Instant Pot is up to the challenge.

Some good background information can be found at this link.

I bet 105°C can work, the expiration date will just have to be adjusted downward or the 105°C cycle time will have to be increased by about 60% vs the 111°C processing temp.

 

[Visitor]

I don't profess to be the expert in the food safety area but I believe that a lower temperature will kill botulism, but it takes a higher temperature to kill botulism spores, and this is why boiling water bath canning isn't recommended for vegetables and meats – I stayed at a Holiday Inn Express last night, but that's about the end of my knowledge (referring to an American commercial).


Interesting discovery about the battery last night. The battery used was a Mirata CR2032W, rated for 125°C. When I pulled the data monitor out of the jar of hot water, the LED was still flashing and the logger was still recording measurements. I took the battery out, and unloaded the data while powered by the PICkit 2.

I put the battery back in last night to see how much longer it would run. A few flashes and it stopped, battery apparently dead. I have a hard time believing that I pulled the data logger out just as the battery was on its last legs....

I wish the datasheet for this battery had some detail but there's not a plot on it. Could it be that the output voltage of the battery is slightly higher at higher temperature? Or maybe the brown out voltage reset on the micro is a little lower at temperature. I need to look at that setting and see if I can lower it a step.

My partner is a 4 hour drive away, taking care of his 95 year old grandmother. I'm headed back again soon (after a mental health break at home) to help him out. Last night he asked me to bring two temperature monitors when I come. No, wait. Three would be better. Bring 3 please. Wait, 4 would let us test 4 jars at once.... At any rate, he has a more advanced true InstraPot there, so it will be interesting to see the differences.

 

[Visitor]

A couple more pictures.

The data logger is vacuum-sealed for the test. There's a small piece of perf board taped by the switches so the vacuumed bag doesn't press them.

Then put in a quart jar of water. If we get a workable temperature range, it will eventually be put in the center of a jar of whatever is being canned.

 

[gophert]

In grad school we were working on chemical sensors to monitor food safety - color change would indicate the food was stored above desired temp for a given time or color change would indicate processing temp was not reached for required time. Ultimately, it turned out to be easiest to not use specific chemical reactions but, instead, use formulation & molding of a wax (low molecular wt polyethylene) to delay contact of two chemicals (Vinegar solution and pH indicator) to show color change. Not as the funding proposal described "customized chemical reactions that match the processing profile...". My professor hated me because rewriting the intermediate data and follow-up funding proposal was way out of his center of experience.

 

[picbits]

I can confirm LEDs can survive some amazing temps and pressures. Color may shift if you get too hot but it is more difficult than you think to kill a 5mm indicator LED - especially the red ones.

Let me just hand one to an intern ............

 

[gophert]

Let me just hand one to an intern ............

They are pretty amazing. Make sure the intern measures the current and pull out the FLIR camera to measure temp.

 

[picbits]

They are pretty amazing. Make sure the intern measures the current and pull out the FLIR camera to measure temp.

They could integrate it into one of their 350 page reports with amazing presentations to the directors of the company while gaining top marks from the assessors. Then a few months after they leave, someone will read the report and realise they didn't really have a clue .... one of the best ones was a design for a power supply to run a test environment. Having pointed out that an LM317 regulating at 12 volts won't start a car the suggestion was that we bought hundreds of LM317s and ran them together.

 

[gophert]

I would blame the mentor - the mentor should be reviewing the intern and guiding the intern with as much oversight as the fully paid staff.

 

[Reloadron]

That was pretty cool or hot as the case may be.

Ron

 

[Visitor]

This topic will probably deserve a post of its own at some point.

Here is a post my partner Eric made on Facebook explaining the why behind this project.

TL;DR - the feds provide minimal support for safe home food preserving research. Gotta science it ourselves.

Now that it’s running, I want to provide some background on why we’re doing this whole project.

The majority of safe canning practices for consumers were developed by land grant university extension programs and the USDA in the early to middle of 20th century - they were refinements on practices that were developed by commercial processors and those developed by consumers as the tools came available to them. Much like other government work, the rules are written in blood - until the development of pressure cookers (really not a Thing for consumers until 1939), people were routinely sickened and killed by home-canned foods, especially those of a low-acid nature like meats and vegetables. Bringing the research capabilities of home economics and food science departments together in the service of the public was considered a good thing for government to do - the USDA largely funded the research but the work was done in places where the crop to be preserved was common - so, for example, the definitive reference on canning seafood at home is from Oregon State, and the definitive method for corn comes out of the Midwest.

Almost all of this research was done when data acquisition was analog - either a grad student with a thermometer or paper chart recorders. The situation in homes was worse - accurate thermometers were expensive and high-precision ones simply didn’t exist. Additionally, the tools available for home pressure canning and heating the pressure canner were dictated by what was out in the market - largely “pressure saucepans” similar to today’s stovetop pressure cookers like Fagors, and “pressure canners” with multi-gallon capacities and either a rocking weight or a dial gauge for pressure regulation.

Safe canning requires particular temperature exposure for specified periods. Because we understand how water vapor behaves, we can extrapolate pressure vessel internal temperature from the pressures reached. Then the question becomes if the food in the jars hits the required temperature with a given combination of time and temperature. Since heat moves through the food through conduction, convection and radiation, the density and nature of the food dictates the time and temperature to a great degree.

The problem is that jar size and closure method, how the food is crammed in, starting temperature, behavior of starchy materials (thickened liquids don’t conduct heat the same as water-thin), altitude, the thermal mass of the canner, the controllability of the heating appliances, etc, all modify the thermal profile of the food. So every recipe recommended for safe canning has to be independently validated - a mushroom and rice soup might not behave the same way as one with carrots and barley, for example.

Great. As long as there are food science grad students there will be *some* growth of safe food preserving recipes - home-canned salsa being an excellent example of a late-20th-Century example of a new safe recipe, and substituting one chile for another is probably just fine. But if you want to do tomatillos instead of red tomatoes? Start over from scratch.

Same goes for heating methods. Since open-kettle methods like sealing jam jars with paraffin (the wax kind, not the kerosene kind, for those in the Commonwealth) or just slapping hot lids on to hot jars filled with hot food were proven unsafe, the methods left to home canners were either “boil covered by two inches of water at atmospheric pressure” (aka Hot Water Bath) or pressure canned. But some failures in the 70s and 80s seemed to indicate that using the smaller pressure saucepans was unsafe, and the raw experimental data were lost to the sands of time, so they fell off the recommended list.

Add in the relative decrease in food prices relative to wages, women in the workforce, increasing urbanization and you just get to a place where the research lags, badly, because the government isn’t interested in funding it and there’s a perception that it appeals to a very small segment of the population.

So things you can’t officially can safely at home with any technique include mashed pumpkin, cream soups, smoked shellfish, thickened pie fillings other than those from a single USDA-developed recipe, celery or anything containing celery. . . the list goes on. And until University of Wisconsin - Madison validated the use of steam baths instead of covering the whole container +2” of water, you had to deal with a giant mass of hot water and metal in your kitchen during the hottest time of the year.

Enter the Instant Pot and ilk. Because they rely on direct electronic temperature measurement rather than inference of temperature from steam pressure levels, they are not recognized as safe methods for canning. But they’re wildly popular, relatively power efficient, don’t steam up the home kitchen and don’t take up a ton of storage space for use once or twice a year. The typical six-quart model does seven half-pint or four pint jars, and they’re AMAZING for steam canning.

But what about pressure canning? Do they get hot enough? Do they heat evenly enough? Do they cool at a similar rate to a pressure canner? More importantly, do the jars of food get to the right temperatures in the right time?

Good question.

I have no grad students. Drilling holes in jar lids and then hermetically sealing them up, and doing the same through pressure vessels is just way too much work. But I have Jon, and I have the need it of digital test and measurement technology, and now I can record this crucial data from inside sealed jars during cooking and processing to figure out if Instant Pots and their ilk are patently dangerous, just need modification from USDA methods or are drop-in replacements. My first project is probably albacore tuna - the home canned version is so incredibly superior to commercial stuff that it’s not even the same fish, and I’d love to be able to do a loin after dinner and not take the whole day making 30 jars.

So that’s why.

 

[gophert]

This topic will probably deserve a post of its own at some point.

Here is a post my partner Eric made on Facebook explaining the why behind this project.

I think that is great but, Ouch, paying for fresh meat and turning into canned meat?
Going to the grocery store more frequently seems much easier, safer and tastier - all without saving any money while doing it. It's not like you're going to buy day-old fish at a discount so you can it. But, it is just my vent - I don't mean to start an argument on the merits of the genesis for your experiments - keep going, I find the challenges interesting.

also, if you have a dry oven, I'd love to see you put your micro/battery/sensor into higher and higher temps until it fails. Or, just the LED on a board with wires going into the oven and raise the temp until the LEDs fail.

 

[Visitor]

I think that is great but, Ouch, paying for fresh meat and turning into canned meat?

You don't want a nice piece of canned filet mignon?. Well, I can't argue with that.

But how about canned fresh albacore tuna? Living in the Pacific Northwest, you can buy fresh tuna off the boat that was caught within the last few hours. Canned with water instead of oil and you'll have great tuna sandwiches year round.

 

[Visitor]

Most often, home canning is used to preserve a seasonal food that's available in abundance at a good price for a short period. Think fruits and jelly/jam. The result is usually a premium product over store-bought items. This is the case for canning fish on the west coast.

Of course, who would pass up a canned whole chicken? Add a can of bread and you're all set!

 

[Nigel Goodwin]

I would blame the mentor - the mentor should be reviewing the intern and guiding the intern with as much oversight as the fully paid staff.

When we were apprentices, and not interns, we often used to put diodes directly across 240V AC mains - makes a nice bang

I presume an LED would be similar? - but by the time LED's appeared, we'd outgrown it (mostly!).

 

[Nigel Goodwin]

Most often, home canning is used to preserve a seasonal food that's available in abundance at a good price for a short period. Think fruits and jelly/jam. The result is usually a premium product over store-bought items. This is the case for canning fish on the west coast.

Of course, who would pass up a canned whole chicken? Add a can of bread and you're all set!

Must say, I've seen (or heard of) either of those

So how much are they?.

 

[Visitor]

Must say, I've seen (or heard of) either of those

So how much are they?.

I think the question is "Why are they?"

I understand the bread is actually pretty good, and costs around three bucks a can.

One review I read about the chicken said "it tastes like all the flavor was cooked out of it." Appears to be kind of expensive at nearly ten bucks.

I have seen both of these items in the grocery store, so there is a demand but I can't imagine why.

 

[Reloadron]

Of course, who would pass up a canned whole chicken? Add a can of bread and you're all set!

Before the MRE (Meal Ready to Eat) there was the C Ration. Interesting thing was I could never tell the difference between canned chicken, pork or a few others. They did include a canned sort of cake or bread. I think the shelf life was something like 50 years. (OK not really) but a long time. All you needed was a P38 can opener. Today there are MREs but I will never forget the C Ration and the canned fruit was pretty good.

Seriously, this was a good thread and you really did a hell of a job. I was not sure things would survive the environment but they did very, very well in the pressure cooker.

Ron

 

[gophert]

My wife's biggest fear about catching Covid was having to eat my cooking - until she heard the pleasant news that a symptom of Covid-19 is loss of smell and taste. So, maybe a tinned-chicken might have its niche market.