Why does frozen food in plastic bags leach when thawing

[Kenny202]

Whenever I put meat or chicken or something in a plastic bag out to thaw always end up with a puddle of blood? How does the blood leach through a sealed plastic bag?

[Oxx]

It's not blood, it's myoglobin.

Either the bag isn't properly sealed, or it's dirty on the outside before you start to thaw.

[Kenny202]

No neither. Happens all the time

[Oxx]

No neither. Happens all the time

Then I suggest you write to the Vatican. It's a miracle, and your meat is clearly in line for beatification.

[canuckamuck]

It happens to me too. Must have something to do with the thawing and the structure of the plastic.

The bags are water tight, but some of the pink juice comes through upon thawing.

[Kenny202]

It happens to me too. Must have something to do with the thawing and the structure of the plastic.

The bags are water tight, but some of the pink juice comes through upon thawing.

No. Didn't you see the reply from the smrt a$$ above? It's a miracle :-)

[Oxx]

It happens to me too. Must have something to do with the thawing and the structure of the plastic.

The bags are water tight, but some of the pink juice comes through upon thawing.

Thinking rationally, if the bags are indeed watertight, a molecule the size of water (molecular weight 18) can't get through. Myoglobin is vastly larger (molecular weight of around 17,000), so also wouldn't be able to pass.

[canuckamuck]

Well they are the same bags in which people put liquids both hot and cold. You know like the hot soup for your noodles. They don't leak when used this way, otherwise they wouldn't use them. I even use these bags for solvent to put my used brushes into while I wait for paint to dry. So if paint thinner doesn't get through they must be watertight. However, if you put meat in them, freeze them, and then defrost them, something leaks out. A miracle according to you, but I am not confident in your explanation.

[Oxx]

However, if you put meat in them, freeze them, and then defrost them, something leaks out. A miracle according to you, but I am not confident in your explanation.

Why do you assume something leaks out? It's far more probable that there are traces of myoglobin on the outside of the bag which dissolve in the condensation that forms on the outside of the bag, giving the pinkish liquid.

[tandor]

..osmosis..same way you drown....

Membranes, whether cell membranes or plastic sandwich bag membranes, allow the passage of certain molecules and prevent passage of others. You may not believe it but sandwich bag plastic permits slow passage of water and other small molecules, but does not allow other larger molecules (or sandwiches) to pass through. This slow passage of water molecules is a type of diffusion (osmosis).

Diffusion is initiated by natural, random molecular .....

Edited July 16, 2016 by tandor

[SoiBiker]

However, if you put meat in them, freeze them, and then defrost them, something leaks out. A miracle according to you, but I am not confident in your explanation.

Why do you assume something leaks out? It's far more probable that there are traces of myoglobin on the outside of the bag which dissolve in the condensation that forms on the outside of the bag, giving the pinkish liquid.

That's exactly what I was going to suggest. The obvious explanation.

[canuckamuck]

That may the case once in a while, but it seems to happen fairly consistently.

I am the one filling the bags and the one defrosting them. I can't see how I am getting so much myoglobin to stick to the bags. It's a pretty clean process. But it occurs to me that it is a bit naff to argue with you guys about something that you can not observe for yourselves. Maybe someone else has experienced the same phenomenon.

[SoiBiker]

Maybe you need to clean your freezer.

[Kenny202]

Maybe you need to clean your freezer.

you ever have anything nice to say SB? :-(

[canuckamuck]

Maybe you need to clean your freezer.

Does your mummy know you are on the internet again bothering the adults.

[ukrules]

Not all of those plastic bags are suitable for freezer use.

 

I have some which leak absolutely zero of anything and you can boil them to defrost / reheat the food straight from frozen.

 

Of course these aren't the cheap ones....I guess you get what you pay for.

[manarak]

22 minutes ago, ukrules said:

Not all of those plastic bags are suitable for freezer use.

 

I have some which leak absolutely zero of anything and you can boil them to defrost / reheat the food straight from frozen.

 

Of course these aren't the cheap ones....I guess you get what you pay for.

 

yes, and not for microwave use either. some bags even set harmful molecules free when frozen.

after doing some research, I found out that bags made of HDPE (High Density PolyEthylene) are the best for food conservation because they can be frozen and microwaved, in theory these bags could withstand temperatures of -80°C up to +135°C, in practice, temps between -30°C up to 95°C are considered okay.

So remember... HDPE !