"DO NOT REFREEZE!" - but why?

Dear Reg:

"Reg" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

N:dlzc D:aol T:com (dlzc) said:

There are biological organisms that can grow once the
ice is gone, and if refrozen at the gentle rate obtainable
in household equipment, can actually continue to grow.
And the temperature difference between freezing and
the food item's temperature is not as large as can be
obtained in a commercial process. Once the center
of something thick is thawed, it is possible for a fairly
vigorous community to keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

The safety issues have very little to do with it. Even your
own cite says it's a quality issue, not a safety one.

Why packages say "Do not refreeze"

Frozen food packers want their products to have a good
image with shoppers. Because quality can deteriorate if
interior product temperatures rang up to 40 degrees
Fahrenheit, many manufacturers do not recommend
refreezing such thawed food because they cannot
guarantee quality under such conditions.

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F. In all likelihood it can
be safely refrozen.

I disagree. "Little or no danger of bacterial growth" is only in
the laboratory.
- *If* the refrigerator is kept closed.
- *If* the refrigerator is allowed to stay at "40 deg F" (and
not asked to cool down a wam dish or three in the interim).
- *If* the refrigerator isn't in my house (basically)
.... then bacteria won't grow. Otherwise, two days later, it is
eat it or pitch it. And don't refreeze it.

I've got a new refrigerator, and keep it fairly clean inside.
But... I've got kids.

David A. Smith

Dear Peter Aitken:

"Peter Aitken" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[email hidden]>
wrote in message news:ONo9f.132506$lq6.87991@fed1read01...

....

Quoted message said:

Quoted message said:

There are biological organisms that can grow once the ice
is gone, and if refrozen at the gentle rate obtainable in
household equipment, can actually continue to grow. And
the temperature difference between freezing and the food
item's temperature is not as large as can be obtained in a
commercial process. Once the center of something thick
is thawed, it is possible for a fairly vigorous community to
keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

It's interesting that the link you give makes no mention of
what you claim.

Did you actually read it?
<QUOTE>
Many refrigerator-freezer compartments cannot reach or maintain 0
degrees Fahrenheit.
<END QUOTE>
.... speaking to normal household equipment.

<QUOTE>
Most partially thawed foods refreeze safely if they still contain
ice crystals and are firm in the center.
<END QUOTE>
.... still frozen in the center, so cultures can't start growing

<QUOTE>
Meat, fish and poultry purposely thawed in the refrigerator and
kept no more than one day may be refrozen. Do not refreeze
thawed meat or poultry pies or casseroles, cream pies or
vegetables.
<END QUOTE>

The only thing they *don't* talk about is the ability of a
culture to use the surrounding "block of ice" as a protective
barrier, allowing growth. Kind of like Eskimos and igloos. But
this was a treatise on "how to" and not "why not".

David A. Smith

Dear Peter Aitken:

"Peter Aitken" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[email hidden]>
wrote in message news:ONo9f.132506$lq6.87991@fed1read01...

....

Quoted message said:

Quoted message said:

There are biological organisms that can grow once the ice
is gone, and if refrozen at the gentle rate obtainable in
household equipment, can actually continue to grow. And
the temperature difference between freezing and the food
item's temperature is not as large as can be obtained in a
commercial process. Once the center of something thick
is thawed, it is possible for a fairly vigorous community to
keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

It's interesting that the link you give makes no mention of
what you claim.

Did you actually read it?
<QUOTE>
Many refrigerator-freezer compartments cannot reach or maintain 0
degrees Fahrenheit.
<END QUOTE>
.... speaking to normal household equipment.

<QUOTE>
Most partially thawed foods refreeze safely if they still contain
ice crystals and are firm in the center.
<END QUOTE>
.... still frozen in the center, so cultures can't start growing

<QUOTE>
Meat, fish and poultry purposely thawed in the refrigerator and
kept no more than one day may be refrozen. Do not refreeze
thawed meat or poultry pies or casseroles, cream pies or
vegetables.
<END QUOTE>

The only thing they *don't* talk about is the ability of a
culture to use the surrounding "block of ice" as a protective
barrier, allowing growth. Kind of like Eskimos and igloos. But
this was a treatise on "how to" and not "why not".

David A. Smith

Dear Peter Aitken:

"Peter Aitken" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[email hidden]>
wrote in message news:ONo9f.132506$lq6.87991@fed1read01...

....

Quoted message said:

Quoted message said:

There are biological organisms that can grow once the ice
is gone, and if refrozen at the gentle rate obtainable in
household equipment, can actually continue to grow. And
the temperature difference between freezing and the food
item's temperature is not as large as can be obtained in a
commercial process. Once the center of something thick
is thawed, it is possible for a fairly vigorous community to
keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

It's interesting that the link you give makes no mention of
what you claim.

Did you actually read it?
<QUOTE>
Many refrigerator-freezer compartments cannot reach or maintain 0
degrees Fahrenheit.
<END QUOTE>
.... speaking to normal household equipment.

<QUOTE>
Most partially thawed foods refreeze safely if they still contain
ice crystals and are firm in the center.
<END QUOTE>
.... still frozen in the center, so cultures can't start growing

<QUOTE>
Meat, fish and poultry purposely thawed in the refrigerator and
kept no more than one day may be refrozen. Do not refreeze
thawed meat or poultry pies or casseroles, cream pies or
vegetables.
<END QUOTE>

The only thing they *don't* talk about is the ability of a
culture to use the surrounding "block of ice" as a protective
barrier, allowing growth. Kind of like Eskimos and igloos. But
this was a treatise on "how to" and not "why not".

David A. Smith

Reg said:

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F.

Although that is true for many of the common bacteria we worry about,
it is certainly not true for all. Listeria is one important food-borne
pathogen that grows quite nicely in the refrigerator.

I do agree with the general consensus that the main problem with
re-freezing is texture, not safety -- assuming you have handled the
food carefully while it was warmer.

To the OP: If you haven’t yet, you might post your original question
to sci.bio.food-science; there is -- sometimes -- some real expertise
there.

bob

Reg said:

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F.

Although that is true for many of the common bacteria we worry about,
it is certainly not true for all. Listeria is one important food-borne
pathogen that grows quite nicely in the refrigerator.

I do agree with the general consensus that the main problem with
re-freezing is texture, not safety -- assuming you have handled the
food carefully while it was warmer.

To the OP: If you haven’t yet, you might post your original question
to sci.bio.food-science; there is -- sometimes -- some real expertise
there.

bob

Reg said:

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F.

Although that is true for many of the common bacteria we worry about,
it is certainly not true for all. Listeria is one important food-borne
pathogen that grows quite nicely in the refrigerator.

I do agree with the general consensus that the main problem with
re-freezing is texture, not safety -- assuming you have handled the
food carefully while it was warmer.

To the OP: If you haven’t yet, you might post your original question
to sci.bio.food-science; there is -- sometimes -- some real expertise
there.

bob

N:dlzc D:aol T:com (dlzc) said:

I disagree. "Little or no danger of bacterial growth" is only in
the laboratory.
- *If* the refrigerator is kept closed.
- *If* the refrigerator is allowed to stay at "40 deg F" (and
not asked to cool down a wam dish or three in the interim).
- *If* the refrigerator isn't in my house (basically)
... then bacteria won't grow. Otherwise, two days later, it is
eat it or pitch it. And don't refreeze it.

I've got a new refrigerator, and keep it fairly clean inside.
But... I've got kids.

If you're really that worried that your refrigerator
spends a significant amount time out of safe range due
to opening a lot, warm dishes, etc, you can put a data logger
on it and find out. I did that once and then never gave it
a thought again because it showed there wasn't any problem.

BTW - There are many people who have children who've
been able make effective use of refrigerators for preserving
their food.

--
Reg email: RegForte (at) (that free MS email service) (dot) com

N:dlzc D:aol T:com (dlzc) said:

I disagree. "Little or no danger of bacterial growth" is only in
the laboratory.
- *If* the refrigerator is kept closed.
- *If* the refrigerator is allowed to stay at "40 deg F" (and
not asked to cool down a wam dish or three in the interim).
- *If* the refrigerator isn't in my house (basically)
... then bacteria won't grow. Otherwise, two days later, it is
eat it or pitch it. And don't refreeze it.

I've got a new refrigerator, and keep it fairly clean inside.
But... I've got kids.

If you're really that worried that your refrigerator
spends a significant amount time out of safe range due
to opening a lot, warm dishes, etc, you can put a data logger
on it and find out. I did that once and then never gave it
a thought again because it showed there wasn't any problem.

BTW - There are many people who have children who've
been able make effective use of refrigerators for preserving
their food.

--
Reg email: RegForte (at) (that free MS email service) (dot) com

N:dlzc D:aol T:com (dlzc) said:

I disagree. "Little or no danger of bacterial growth" is only in
the laboratory.
- *If* the refrigerator is kept closed.
- *If* the refrigerator is allowed to stay at "40 deg F" (and
not asked to cool down a wam dish or three in the interim).
- *If* the refrigerator isn't in my house (basically)
... then bacteria won't grow. Otherwise, two days later, it is
eat it or pitch it. And don't refreeze it.

I've got a new refrigerator, and keep it fairly clean inside.
But... I've got kids.

If you're really that worried that your refrigerator
spends a significant amount time out of safe range due
to opening a lot, warm dishes, etc, you can put a data logger
on it and find out. I did that once and then never gave it
a thought again because it showed there wasn't any problem.

BTW - There are many people who have children who've
been able make effective use of refrigerators for preserving
their food.

--
Reg email: RegForte (at) (that free MS email service) (dot) com

Bob said:

Reg said:

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F.

Although that is true for many of the common bacteria we worry about,
it is certainly not true for all. Listeria is one important food-borne
pathogen that grows quite nicely in the refrigerator.

Yes, listeria is one of the few that grows at lower temps.
I've never seen anything that shows that thawing and
refreezing makes something it especially vulnerable to
listeria though, especially if it's thawed at fridge
temps.

Quoted message said:

I do agree with the general consensus that the main problem with
re-freezing is texture, not safety -- assuming you have handled the
food carefully while it was warmer.

Refreezing almost anything will damage it's texture.
If I ever refreeze something (which is almost never), it
doesn't end up getting served in a form where texture is
important. Meat would likely end up in the stockpot,
vegetables would be pureed, etc.

--
Reg email: RegForte (at) (that free MS email service) (dot) com

Bob said:

Reg said:

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F.

Although that is true for many of the common bacteria we worry about,
it is certainly not true for all. Listeria is one important food-borne
pathogen that grows quite nicely in the refrigerator.

Yes, listeria is one of the few that grows at lower temps.
I've never seen anything that shows that thawing and
refreezing makes something it especially vulnerable to
listeria though, especially if it's thawed at fridge
temps.

Quoted message said:

I do agree with the general consensus that the main problem with
re-freezing is texture, not safety -- assuming you have handled the
food carefully while it was warmer.

Refreezing almost anything will damage it's texture.
If I ever refreeze something (which is almost never), it
doesn't end up getting served in a form where texture is
important. Meat would likely end up in the stockpot,
vegetables would be pureed, etc.

--
Reg email: RegForte (at) (that free MS email service) (dot) com

Bob said:

Reg said:

If you thaw something in the refrigerator there's
little or no danger of bacterial growth, which doesn't
occur much below 40 F.

Although that is true for many of the common bacteria we worry about,
it is certainly not true for all. Listeria is one important food-borne
pathogen that grows quite nicely in the refrigerator.

Yes, listeria is one of the few that grows at lower temps.
I've never seen anything that shows that thawing and
refreezing makes something it especially vulnerable to
listeria though, especially if it's thawed at fridge
temps.

Quoted message said:

I do agree with the general consensus that the main problem with
re-freezing is texture, not safety -- assuming you have handled the
food carefully while it was warmer.

Refreezing almost anything will damage it's texture.
If I ever refreeze something (which is almost never), it
doesn't end up getting served in a form where texture is
important. Meat would likely end up in the stockpot,
vegetables would be pureed, etc.

--
Reg email: RegForte (at) (that free MS email service) (dot) com

JS said:

On a lot of food items it says that it can be frozen but once it is
thawed it must not be re-frozen.

Why mus they not be refrozen? What is the scientific basis for such
a statement?

---

I believe that slow freezing forms large ice crystals which can
damage the structure of the cell membrane of foods and so impair
taste. If refreezing also impairs taste then that's too bad but at
least it does not seem to be dangerous.

This is more of a taste issue than a health issue. Proteins and cell
walls are destroyed partially on freezing and especially badly on
thaw/freeze cycles. Thaw/freeze cycling is a good way to destroy
cells, bacteria included.

As far as bacteria go, many bacterial cells are much more resistant to
freezing and thawing than plant tissues, and especially animal tissues.
Bacterial cells are much smaller and have protective cell walls.
Plant cells have cellulose-based cell walls, and animal cells nothing
but a membrane. But growth while frozen will be next to nothing,
growth while still cold but not frozen will be minimal, and so long as
you thoroughly cook it afterwards, shouldn't be a health issue unless
you have meat already infested with a bad strain of E. coli or
salmonella and eat it half-raw. Add up the total time the food is
thawed and treat it as if it were in the fridge sitting that long.

There's a remote danger that if your freezer isn't operating properly,
there are many more slight thaw cycles than you would otherwise know
about, allowing additional growth.

JS said:

On a lot of food items it says that it can be frozen but once it is
thawed it must not be re-frozen.

Why mus they not be refrozen? What is the scientific basis for such
a statement?

---

I believe that slow freezing forms large ice crystals which can
damage the structure of the cell membrane of foods and so impair
taste. If refreezing also impairs taste then that's too bad but at
least it does not seem to be dangerous.

This is more of a taste issue than a health issue. Proteins and cell
walls are destroyed partially on freezing and especially badly on
thaw/freeze cycles. Thaw/freeze cycling is a good way to destroy
cells, bacteria included.

As far as bacteria go, many bacterial cells are much more resistant to
freezing and thawing than plant tissues, and especially animal tissues.
Bacterial cells are much smaller and have protective cell walls.
Plant cells have cellulose-based cell walls, and animal cells nothing
but a membrane. But growth while frozen will be next to nothing,
growth while still cold but not frozen will be minimal, and so long as
you thoroughly cook it afterwards, shouldn't be a health issue unless
you have meat already infested with a bad strain of E. coli or
salmonella and eat it half-raw. Add up the total time the food is
thawed and treat it as if it were in the fridge sitting that long.

There's a remote danger that if your freezer isn't operating properly,
there are many more slight thaw cycles than you would otherwise know
about, allowing additional growth.

JS said:

On a lot of food items it says that it can be frozen but once it is
thawed it must not be re-frozen.

Why mus they not be refrozen? What is the scientific basis for such
a statement?

---

I believe that slow freezing forms large ice crystals which can
damage the structure of the cell membrane of foods and so impair
taste. If refreezing also impairs taste then that's too bad but at
least it does not seem to be dangerous.

This is more of a taste issue than a health issue. Proteins and cell
walls are destroyed partially on freezing and especially badly on
thaw/freeze cycles. Thaw/freeze cycling is a good way to destroy
cells, bacteria included.

As far as bacteria go, many bacterial cells are much more resistant to
freezing and thawing than plant tissues, and especially animal tissues.
Bacterial cells are much smaller and have protective cell walls.
Plant cells have cellulose-based cell walls, and animal cells nothing
but a membrane. But growth while frozen will be next to nothing,
growth while still cold but not frozen will be minimal, and so long as
you thoroughly cook it afterwards, shouldn't be a health issue unless
you have meat already infested with a bad strain of E. coli or
salmonella and eat it half-raw. Add up the total time the food is
thawed and treat it as if it were in the fridge sitting that long.

There's a remote danger that if your freezer isn't operating properly,
there are many more slight thaw cycles than you would otherwise know
about, allowing additional growth.

"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[email hidden]> wrote in
message news😄iB9f.47$bo.44@fed1read01...

Quoted message said:

Dear John Kane:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

N:dlzc D:aol T:com (dlzc) said:

Dear JS:

"JS" <[email hidden]> wrote in message
news:[email hidden]...
> On a lot of food items it says that it can be frozen but
> once it is thawed it must not be re-frozen.
>
> Why mus they not be refrozen? What is the scientific
> basis for such a statement?

There are biological organisms that can grow once the
ice is gone, and if refrozen at the gentle rate obtainable
in household equipment, can actually continue to grow.
And the temperature difference between freezing and
the food item's temperature is not as large as can be
obtained in a commercial process. Once the center
of something thick is thawed, it is possible for a fairly
vigorous community to keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

http://www.hkpr.on.ca/healthy-environments-master.asp?id=207 ??

<QUOTE>
Discard any food which has completely thawed, and has been at room
temperature for an unknown period of time.
<END QUOTE>

David A. Smith

Why are you quoting that? It is completely different from what was claimed
originally.

--
Peter Aitken

"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[email hidden]> wrote in
message news😄iB9f.47$bo.44@fed1read01...

Quoted message said:

Dear John Kane:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

N:dlzc D:aol T:com (dlzc) said:

Dear JS:

"JS" <[email hidden]> wrote in message
news:[email hidden]...
> On a lot of food items it says that it can be frozen but
> once it is thawed it must not be re-frozen.
>
> Why mus they not be refrozen? What is the scientific
> basis for such a statement?

There are biological organisms that can grow once the
ice is gone, and if refrozen at the gentle rate obtainable
in household equipment, can actually continue to grow.
And the temperature difference between freezing and
the food item's temperature is not as large as can be
obtained in a commercial process. Once the center
of something thick is thawed, it is possible for a fairly
vigorous community to keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

http://www.hkpr.on.ca/healthy-environments-master.asp?id=207 ??

<QUOTE>
Discard any food which has completely thawed, and has been at room
temperature for an unknown period of time.
<END QUOTE>

David A. Smith

Why are you quoting that? It is completely different from what was claimed
originally.

--
Peter Aitken

"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[email hidden]> wrote in
message news😄iB9f.47$bo.44@fed1read01...

Quoted message said:

Dear John Kane:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

N:dlzc D:aol T:com (dlzc) said:

Dear JS:

"JS" <[email hidden]> wrote in message
news:[email hidden]...
> On a lot of food items it says that it can be frozen but
> once it is thawed it must not be re-frozen.
>
> Why mus they not be refrozen? What is the scientific
> basis for such a statement?

There are biological organisms that can grow once the
ice is gone, and if refrozen at the gentle rate obtainable
in household equipment, can actually continue to grow.
And the temperature difference between freezing and
the food item's temperature is not as large as can be
obtained in a commercial process. Once the center
of something thick is thawed, it is possible for a fairly
vigorous community to keep the center from freezing.
http://muextension.missouri.edu/explore/miscpubs/mp0556_01.htm

http://www.hkpr.on.ca/healthy-environments-master.asp?id=207 ??

<QUOTE>
Discard any food which has completely thawed, and has been at room
temperature for an unknown period of time.
<END QUOTE>

David A. Smith

Why are you quoting that? It is completely different from what was claimed
originally.

--
Peter Aitken

N:dlzc D:aol T:com (dlzc) said:

I disagree. "Little or no danger of bacterial growth" is only in
the laboratory.
- *If* the refrigerator is kept closed.
- *If* the refrigerator is allowed to stay at "40 deg F" (and
not asked to cool down a wam dish or three in the interim).
- *If* the refrigerator isn't in my house (basically)

[snip]

Quoted message said:

I've got a new refrigerator, and keep it fairly clean inside.
But... I've got kids.

You also have two controls available that should mostly mitigate the
problem of the 'fridge's temperature climbing too high. First is this:
"Hey! Don't just stand there, close the damn door!" Second is the
thermostat: turn it down. -aem