cooking chicken pot pies in a microwave oven

[O. Peter Snyder, Jr., Ph.D.]

Dear foodsafe,

We just went to the grocery store here in Minnesota to find out if we could buy a Banquet frozen chicken pot pie, and they have all been pulled off the shelves.  Our intent was to heat them in our office microwave oven according to the box instructions to find out what food temperature we achieved, because microwave ovens are notorious for not heating food thoroughly. 

Instead, we bought three 7-oz. Swanson frozen chicken pot pies, which are the same weight, 7 oz., as the Banquet frozen chicken pot pies, heated them in a 830-watt microwave oven for the recommended 4 minutes on high, and then, let them sit for 3 minutes to equilibrate.  The box does say, in small type, that tests were done using a 1,100-watt microwave oven.  Swanson's instructions are exactly the same as those found on the Banquet frozen chicken pot pie, which I purchased at the grocery store, on Tuesday evening, before they were taken off the market. 

The Swanson's label also says, in very small type, "This product must be cooked to an internal temperature greater than 150ºF prior to eating."  The problem is that the pie is only an inch thick.  So, if consumers use bimetallic coil thermometers to measure food temperature, they will have no idea what the actual center temperature of the pot pie is.  Also, only a very few people have thermometers of any type. 

We cooked the 3 pot pies for 4 minutes in the microwave oven on high, let them sit for 3 minutes, and measured their temperature using an Atkins series 330 thermocouple thermometer.  Here are the results. 

Pie #1: 
After 4 minutes of cooking, temperature 178 to 103F
After 3 minutes sitting 170 to 115F:  unsafe

Pie#2:
After 4 minutes of cooking, temperature 182-68F
After 3 minutes sitting 150-121F:  unsafe

Pie#3
After 4 minutes of cooking, temperature 177-43F
After 3 minutes sitting 140-76F:  unsafe

It appears from the ingredients that Swanson pre-cooks the ingredients, whereas Banquet did include an ingredient that may not have been adequately cooked to destroy Salmonella ["cooked mechanically separated chicken" (Swanson) vs. "mechanically separated chicken" (Banquet)]. 

I know of no USDA inspector who checks the cooking instructions on the side of food containers to find out if they are adequate to make the food safe.  This is an assumed responsibility of the manufacturer. 

There appears to be a major issue here.  Most manufacturers of frozen meals had better cook the ingredients thoroughly and only sell cooked, ready-to-eat food, because, if they rely on consumers to follow their instructions, the instructions do not appear to be adequate for frozen meals, and certainly, most consumers will not have tip-sensitive thermometers (thermistors or thermocouples) to assure that there are no cold spots in these meals where Salmonella can survive. 

Maybe it is time for food manufacturers to include free thermometers in all of the foods that they sell. 

-- 
O. Peter Snyder, Jr., Ph.D.
Hospitality Institute of Technology and Management
670 Transfer Road, Suite 21A; St Paul, Minnesota  55114; USA
http://www.hi-tm.com
Tel 651-646-7077   FAX 651-646-5984 
One worldwide uniform set of retail food safety guidelines

[Peter Esko]

That's a great idea, Pete, but what is the accuracy of the popup thermometers used in turkeys?  If they do work properly, a similar device could be used in the pies, but would increase the cost per pie.  They could include Ecolab stick thermometers pretty cheaply right in the package, a cellophane-wrapped insert with instructions -- but would the consumer mostly throw out the thermometers without using?   Sounds like another topic for a study on consumer KAPs.

 

Peter

 

Peter Esko, REHS
Environmental Scientist
Del Norte County Public Health Branch
880 Northcrest Drive
Crescent City, CA 95531
707-464-3191 x295 (phone)
707-465-1792
pe...@co.del-norte.ca.us

[Aqu...@aol.com]

Out of curiosity Pete where did you poke the pies for temperature (depth, distance from center)? Were the coldest temperatures in the same location from pie to pie? Did the microwave rotate the pies during cooking? Do you think that variations from pie to pie are an oven issue and/or an issue of the contents variation from pie to pie?

 

Thanks,

 

Alan Ismond, P.Eng.
Aqua-Terra Consultants

---

See what's new at AOL.com and Make AOL Your Homepage.

[Doug Powell]

I did a similar experiment yesterday.
The pics and results are at:

http://barfblog.foodsafety.ksu.edu/2007/10/articles/food-safety-
communication/cooking-a-frozen-pot-pie-in-a-microwave/

and if that doesn't work, it's the third post (currently) at
barfblog.com
dp

Dr. Douglas Powell
associate professor
scientific director
International Food Safety Network
dept. diagnostic medicine/pathobiology
Kansas State University
Manhattan, KS
66506
cell: 785-317-0560
fax: 785-532-4039
dpo...@ksu.edu
foodsafety.ksu.edu

On 11-Oct-07, at 5:48 PM, Aqu...@aol.com wrote:

> Out of curiosity Pete where did you poke the pies for temperature
> (depth, distance from center)? Were the coldest temperatures in the
> same location from pie to pie? Did the microwave rotate the pies
> during cooking? Do you think that variations from pie to pie are an
> oven issue and/or an issue of the contents variation from pie to pie?
>
> Thanks,
>
> Alan Ismond, P.Eng.
> Aqua-Terra Consultants
>
>
>

[TLS4...@aol.com]

Pete -

 

Re Doug Powell's "barfblog" and your experiment.  He said that the label read to cook longer (I think it was 5 or 6 minutes) on high in lower powered microwave ovens like the one you used.  I'm not defending Conagra or its label, because most folks haven't a clue as to the wattage of their microwave.  [And are in a big hurry.]  But you pointed out that with an 1,100 watt microwave, the package recommends 4 minutes.  It is only fair to follow the manufacturer's instructions when checking if the directions yield a safe product. 

 

Tom Schwarz

---

[Doug Powell]

one of the things I, and several of my students in class picked up on
yesterday was, even if you know your microwave wattage, what
constitutes high, medium, or low wattage?

regardless, go look in the frozen food section of your supermarket;
there is every kind of frozen meat thingies -- some pre-cooked, some
raw, some with directions to cook to 165F, some with nothing -- it's
all very confusing

Something happened at the plant to allow a big dose of salmonella
into the product; but expecting consumers to clean up the mess seems
misguided at best

dp

Dr. Douglas Powell
associate professor
scientific director
International Food Safety Network
dept. diagnostic medicine/pathobiology
Kansas State University
Manhattan, KS
66506
cell: 785-317-0560
fax: 785-532-4039
dpo...@ksu.edu
foodsafety.ksu.edu

On 11-Oct-07, at 6:09 PM, TLS4...@aol.com wrote:

> Pete -
>
> Re Doug Powell's "barfblog" and your experiment. He said that the
> label read to cook longer (I think it was 5 or 6 minutes) on high
> in lower powered microwave ovens like the one you used. I'm not
> defending Conagra or its label, because most folks haven't a clue
> as to the wattage of their microwave. [And are in a big hurry.]
> But you pointed out that with an 1,100 watt microwave, the package
> recommends 4 minutes. It is only fair to follow the manufacturer's
> instructions when checking if the directions yield a safe product.
>
> Tom Schwarz
>
>
>

[Pete Snyder]

Tom,  This was not intended to be a lab test. It was just a typical consumer test with a consumer, me, whose microwave happened to have that wattage on the label.  The age of the microwave makes a lot of difference because the older they get the less power they produce.  What the test showed me was the pot pie wasn't even close to being done. In my 50 year experience with microwave ovens, another minute wouldn't have helped a lot. When a food company writes  microwave instruction for food, especially to make it safe, they should be smart enough to know they will get very poor results because of all the microwave oven operating problems coupled with the cook making bad judgments.  There are a lot of frozen meals with microwave instructions for sale in the market. If companies are counting on the microwave to make the food safe, they had better check. 

Pete

-- 
O. Peter Snyder, Ph.D.  email: osn...@hi-tm.com
Hospitality Institute of Technology and Management
URL: http://www.hi-tm.com 
670 Transfer Rd, St Paul MN, 55114 
Tel: 651-646-7077  FAX: 651-646-5984
One worldwide set of validated food safety procedures  

[William Marler]

Con Agra recalled all products as of an hour ago.

On 10/11/07 7:38 PM, "Pete Snyder" <osn...@hi-tm.com> wrote:

Tom,  This was not intended to be a lab test. It was just a typical consumer test with a consumer, me, whose microwave happened to have that wattage on the label.  The age of the microwave makes a lot of difference because the older they get the less power they produce. What the test showed me was the pot pie wasn't even close to being done. In my 50 year experience with microwave ovens, another minute wouldn't have helped a lot. When a food company writes  microwave instruction for food, especially to make it safe, they should be smart enough to know they will get very poor results because of all the microwave oven operating problems coupled with the cook making bad judgments.  There are a lot of frozen meals with microwave instructions for sale in the market. If companies are counting on the microwave to make the food safe, they had better check.  

Pete

TLS4...@aol.com wrote:

  
Pete -
 
 
 
Re Doug Powell's "barfblog" and your experiment.  He said that the label read to cook longer (I think it was 5 or 6 minutes) on high in lower powered microwave ovens like the one you used.  I'm not defending Conagra or its label, because most folks haven't a clue as to the wattage of their microwave.  [And are in a big hurry.]  But you pointed out that with an 1,100 watt microwave, the package recommends 4 minutes.  It is only fair to follow the manufacturer's instructions when checking if the directions yield a safe product.
 
 
 
Tom Schwarz
 

 
 
 

---

See what's new at AOL.com <http://www.aol.com?NCID=AOLCMP00300000001170> and Make AOL Your Homepage <http://www.aol.com/mksplash.adp?NCID=AOLCMP00300000001169> .

William D. Marler
Marler Clark LLP PS
6600 Columbia Center
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Seattle, WA 98104
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See also, www.marlerblog.com

[Ted Labuza]

Back in the early 1990s, if I remember right a  Professor Pennington in the UK blamed improper heating of frozen foods in the microwave oven as the reason for the increase in salmonellosis which made wide headlines. This inspired a group I was consulting with at 3M to come up with a simple device that could be put in side the package that would respond to time temperature history and indicate when the food was done. We played around with many design and found that a domed plastic top was best and the device was a strip of porous medium with uniform pores that had a blue dyed wax at each end and that melted at about 50 °C, One melted each side  diffused towards the center of the tag with a consistent moving front  Eugenia Davis of our department showed that with frozen foods the heat penetration in a microwave food followed Lambert’s Law (linear) if under ~ 1 inch thickness while it followed Maxwell Equations (Sine wave) if thicker. The latter  yields hot and cold pockets. So this was designed for 1” thick foods. Kathy Nelson did the work in my lab for testing this under different conditions and we published it in JFP see below)  It was purchased by Armour for some of their frozen meals at that time, 25 million tags if I remember. But because of the cost , I think ~ 6 cents , they discontinued it.   Armour at that time I think was a  a Division of ConAgra  who I think  sold it to Dial. Note also that 3M  has retired this technology, perhaps it should be reborn..
PS I don’t have reprints and paper is not available on the web. I will try to find the journal and make some copies of the article.

-- Nelson, K. and Labuza, T.P.  1992. Kinetics of closure of microwave doneness indicators.  J. Food Protection 55(3): 203-207
Dr. Ted Labuza  
Morse Alumni Distinguished Teaching Professor of Food Science and Engineering
Department of Food Science and Nutrition Univ. of Minnesota  Rm. 136 A 1354 Eckles Ave. St Paul 55108
email - tpla...@umn.edu Text Msg 65130...@mobile.mycingular.com  Cell 651-307-2985
Office ( 612-624-9701            UM 7  fax 612-625-5272          NFNC 7   Fax 661-483-3302
web     http://www.ardilla.umn.edu/Ted_Labuza

---

From: Peter Esko <pe...@co.del-norte.ca.us>
Date: Thu, 11 Oct 2007 15:28:11 -0700
To: foodsafe <Foodsa...@googlegroups.com>, "Jr. Ph.D. O. Peter Snyder" <osn...@hi-tm.com>
Subject: [Foodsafe] Re: cooking chicken pot pies in a microwave oven

[Peter Snyder]

Ted, excellent.

I have a copy iof Ted's paper in my library. If anyone would lile a
copy, contact me.

Pete

Ted Labuza wrote:

> doneness indicators. _J. Food Protection_ 55(3): 203-207
> /Dr. Ted Labuza

> Morse Alumni Distinguished Teaching Professor of Food Science and
> Engineering

> /Department of Food Science and Nutrition Univ. of Minnesota Rm. 136 A

> 1354 Eckles Ave. St Paul 55108

> email - /tpla...@umn.edu/ Text Msg /65130...@mobile.mycingular.com/
> Cell 651-307-2985

> Office ( 612-624-9701 UM 7 fax 612-625-5272 NFNC 7 Fax 661-483-3302

> web http://www.ardilla.umn.edu/Ted_Labuza
>
>
>
> ------------------------------------------------------------------------
> *From: *Peter Esko <pe...@co.del-norte.ca.us>
> *Date: *Thu, 11 Oct 2007 15:28:11 -0700
> *To: *foodsafe <Foodsa...@googlegroups.com>, "Jr. Ph.D. O. Peter
> Snyder" <osn...@hi-tm.com>
> *Subject: *[Foodsafe] Re: cooking chicken pot pies in a microwave oven

>
> That's a great idea, Pete, but what is the accuracy of the popup
> thermometers used in turkeys? If they do work properly, a similar
> device could be used in the pies, but would increase the cost per pie.
> They could include Ecolab stick thermometers pretty cheaply right in
> the package, a cellophane-wrapped insert with instructions -- but
> would the consumer mostly throw out the thermometers without using?
> Sounds like another topic for a study on consumer KAPs.
>
> Peter
>
> Peter Esko, REHS
> Environmental Scientist
> Del Norte County Public Health Branch
> 880 Northcrest Drive
> Crescent City, CA 95531
> 707-464-3191 x295 (phone)
> 707-465-1792
> pe...@co.del-norte.ca.us
>
>
>
>
> >

--

O. Peter Snyder, Jr., Ph.D.

Hospitality Institute of Technology and Management

670 Transfer Road, Suite 21A; St Paul, Minnesota 55114; USA
http://www.hi-tm.com

Tel 651-646-7077 FAX 651-646-5984