6 replies to this topic

[jcieslowski]

I'm currently struggling to wrap my brain around a verification on a cooking process in my facility.  We have a pressure cooker to cook beans.  FDA requires that beans are cooked at 200°F for 3 minutes to render safe to eat.  Our cooker (which is pressurized), cooks at a minimum of 230°F.  All of our programs have dwell times of 9 minutes plus.  There is a digital readout of the temperature and an analogue thermometer dial on the side of the cooker.  

 

Weekly, as part of a weekly walkthrough, the QA manager (me) documents the analogue temperature against the digital readout to ensure they're the same (always have been so far).  Monthly, the QA manager (still me) compares the analogue thermometer when the machine is off (ambient) to a certified lollypop style thermometer (we just get a new one each year as opposed to re-calibrating / re-certifying).

 

Recently, my FDA inspector challenged (I'm a little annoyed because she said it was just a discussion point for us but then wrote it up as a violation) that just because the calibrated thermometer matches the analogue thermometer at ambient conditions does not mean it would match it at temperature (don't think I agree on this point) and that comparing the digital and analogue at temperature doesn't ensure that either is right (which I sort of agree with this part - it's all dependent on the first thing).

 

Anyway, if someone could just tell me that I'm not completely crazy for thinking this is a bit much, I'd appreciate that but what I REALLY am looking for is ideas on how to address this.

 

I can't put anything into the cooker.  It's got a corkscrew, some screens, and a water fed chute that I'm afraid of getting anything stuck in.   The cooker is at pressure, so I can't measure the inside from the outside.   I tried using a temp gun to find the hottest part of the metal but it's double walled so I'm seeing a 20° drop from the thermometers to the outside of the cooker.  

 

Anyone experience anything similar and what do y'all do?

[TimG]

"Recently, my FDA inspector challenged (I'm a little annoyed because she said it was just a discussion point for us but then wrote it up as a violation)"

Huh..did the same thing to me in my last visit. Wrote up a bunch of 'talking points' as violations...

 

Anyway, we have ports right after our inline therms that we can take a high temp sample of to match our annually replaced NIST calib therm. I would agree that ambient temps wouldn't work for accuracy checks, and you would want to check accuracy in the range of what your process therm is working at.

 

It helps that our temp thresholds are for processing only (quality), not food safety. 

[GMO]

I'm currently struggling to wrap my brain around a verification on a cooking process in my facility.  We have a pressure cooker to cook beans.  FDA requires that beans are cooked at 200°F for 3 minutes to render safe to eat.  Our cooker (which is pressurized), cooks at a minimum of 230°F.  All of our programs have dwell times of 9 minutes plus.  There is a digital readout of the temperature and an analogue thermometer dial on the side of the cooker.  

 

Weekly, as part of a weekly walkthrough, the QA manager (me) documents the analogue temperature against the digital readout to ensure they're the same (always have been so far).  Monthly, the QA manager (still me) compares the analogue thermometer when the machine is off (ambient) to a certified lollypop style thermometer (we just get a new one each year as opposed to re-calibrating / re-certifying).

 

Recently, my FDA inspector challenged (I'm a little annoyed because she said it was just a discussion point for us but then wrote it up as a violation) that just because the calibrated thermometer matches the analogue thermometer at ambient conditions does not mean it would match it at temperature (don't think I agree on this point) and that comparing the digital and analogue at temperature doesn't ensure that either is right (which I sort of agree with this part - it's all dependent on the first thing).

 

 

Sorry. But I agree with the inspector. Albeit I don't agree on raising something after they've left site.

When you're using a thermocouple for a CCP, or any measuring device really, you need to measure it over the range you want it to be accurate over. Not just at a single point and not even multiple points far away from the temperature you need to be sure it's at so the food is safe.

 

So if we go back to your cooker. It cooks at 230F for 9 minutes.

 

So your dwell time is 9 minutes, you'd want to be sure that's accurate and your temperature is 230F.

 

You have a digital readout of the temperature. Therefore there is at least one temperature probe in the system. Calibrate it. And if you need someone to come in to do that for you, why would you skimp on that out of all things you have in your process? How they'd do it? I guess they may be able to detach it and test it in a heat block? Unsure. But ask an engineer who knows what they're doing.

 

If you did find a way to do it yourself, the old phrase is it must be tested against something which is "calibrated and traceable to national standards". So if your probe you're testing it against is calibrated against a reference probe which is calibrated to national standards (it would be UKAS in the UK, not sure in the US) then fine. But you'd still need to test more than one data point spanning the range you're interested in.

 

Lastly, I'm not sure on your cooker. But even pressurised canning systems have dataloggers specifically designed to be used within them. These kinds of things. Although if you're cooking the beans in a free flowing process, I'm wondering if you could attach the second in some way to a part of the process so it's not clattering around inside?

 

Canning logger for thermal food treatment in retorts and sterilizers

EBI 11-T230 Robust logger for sample control

 

Just a thought. But calibrating the existing probes will probably be easier.  Also if you do have two probes in the system (and the digital and analogue read out are genuinely linked to two different probes) that's helpful as well to monitor there's no drift between calibrations. I'd get my team members checking that and have a limit how far apart they're allowed to be before you stop.

[dsglinski]

I'd agree that temperature measuring devices can (and often do) have variation in their accuracy/correction factors across large temperature ranges. 

 

Coming from more of a laboratory background, I would consider the option of using a datalogger purpose made for high pressure, high temperature, waterproof use. I've used HOBO Dataloggers from Onset for temperature stability studies, validation and verification studies of laboratory autoclave cycles. It's likely this sort of instrumentation would allow you to go above the bare minimum in showing your time at temperature in your pressure cooker.

 

For example, I've used this model before: https://www.onsetcom...loggers/u12-015

[jcieslowski]

"Just a thought. But calibrating the existing probes will probably be easier."  - I think this is the answer!   Thanks, now to find someone who can do that.

 

Much obliged. 

[Tony-C]

"Just a thought. But calibrating the existing probes will probably be easier."  - I think this is the answer!   Thanks, now to find someone who can do that.

 

Much obliged. 

 

Hi jcieslowski,

 

I’m of the view that all process thermometers should be calibrated anyway?

 

I have come across this scenario previously supplying USAF according to the PMO standard and we used to remove dual thermometer probes (for auto-divert) whilst they were still operational and test them in a water bath against the NPL calibrated thermometer. Something you could look at as you could test up to around 210F with boiling water.

 

Kind regards,

 

Tony

[GMO]

 

I’m of the view that all process thermometers should be calibrated anyway?

 

I have come across this scenario previously supplying USAF according to the PMO standard and we used to remove dual thermometer probes (for auto-divert) whilst they were still operational and test them in a water bath against the NPL calibrated thermometer. Something you could look at as you could test up to around 210F with boiling water.

 

Yep I agree. I brought it up because I thought if records were available of this, they would have shown them. Still, worth checking Engineering aren't already doing it.

 

You've made me think though Tony. Is there the potential to do a more frequent verification of the probes as well? If you can't easily remove the probes (although it would be great if you could) If this is a flow cooking system for beans, could you run water through that flow at cold and hot temperatures and measure it with a handheld probe, ideally if there's a recirculation mode so everything is stabilised? (I'm not sure if the temperature is the same throughout.) Could be an option if you can do it safely with hot water and with cold water.