[shel]

Recently I saw an article that said it was unwise to keep cooking oil (Olive, Safflower, Canola, etc.) in plastic containers due to some sort of health risk. At least that's what I recall. The article did go on to say that any oil should be removed from the plastic container and put into glass as soon as possible. Does anyone have more information about this?

Shel

[Luc_H]

Hi Shel,

all plastics have residual polymer reactants and additives that are not necessary locked in and can leach out. One notable compound that has caught the attention of the media is Bisphenol A. Bisphenol A - Wikipedia, the free encyclopedia
There are others.

The food and packaging industry has tried to solve this problem by making High Density PolyEthylene (HDPE) which is considered one of the most cost efficient and least reactive (or leaching) plastics hence approved for food use.

Plastic will never by as inert (unreactive) as glass or stainless steel. I do not consider it a major concern but I do have a tendency of purchasing EVOO in cans only and veggy oil in glass. The whole industry has converted to plastic so that every time you eat food service, the oil used was stored in a bucket.

Luc

[Cat Man]

I believe that exposure to light also has an impact on the oil.

Cat Man

[KYHeirloomer]

Luc,

Ask me, sometime, about Dr. Gilbert; Maxwell's Demons; and the U.S. Congress as applied to the migration of free monomers in food-grade plastic.

If you want to hear it, PM me, only cuz I think everybody else would be bored.

[OregonYeti]

Luc, you know your chemistry. Great complement to cooking skills, and perhaps you would say essential.

[Cat Man]

Hey Kentucky
I'm extremely interested in learning more about what you're saying.
I promise I won't get bored

Cat Man

[Luc_H]

Hey thanks OregonYeti!
I started in food chemistry first then appreciated the culinary art later. I have an odd mixture of nutrition, science and cooking skills now. I like to cross reference things across these disciplines (an others).

KYH,
I want to hear (read) your thing about Dr. Gilbert. I guess PMing will be more appropriate. I think Cat man wants to be cc'd also. I would appreciate it... thanks!

You are right on the light factor Mr. Cat. Particularly fluorescent lighting that emit some UV which is more damaging (like sunlight).

Luc

[shel]

Originally Posted by Cat Man

Hey Kentucky
I'm extremely interested in learning more about what you're saying.
I promise I won't get bored

Cat Man

Me too ...

Shel

[KYHeirloomer]

OK, y’all asked for it.

First, for those who are unaware of it, we’ll discuss, in oversimplifed terms, Maxwell’s Demons theory.

Originally a thought experiment conducted by James Maxwell in 1867, it had to do with theoretical violations of the second law of thermodynamics. It has since been used, by physicists and others, to explain the observed violation of that law.

Here’s how to visualize it. If you take a semi-permeable membrane, molecules in solution will move from the area of highest concentration to lowest. So, if you have fresh water on one side and salt water on the other, the salty water will osmose to the fresh. Hot water will osmose to the cold.

Y’all taking notes? There will be a quiz on Friday.

Ultimately, we’re talking about the laws controlling entropy, but that’s too confusing for a food message board.

Now comes the kicker. Every once in a while the direction of flow is reversed. A cold water molecule will move to the hot side, or a fresh molecule to the salty side. There is, even today, no explanation for this phenomenon.

Enter Maxwell’s Demons.

If you magnify the membrane umpty ump times, you’ll see that it resembles a cargo net. Each opening in the net is a gate, controlled by a ***** who sits there directing traffic. Every once in a while a ***** falls down on the job, and let’s a molecule escape in the wrong direction.

Still with me? This will count as 1/3 of your midterm grade.

The thing to understand is that scientists find it embarrassing to say “I dunno.” So Maxwell’s Demons is used, quite seriously, to explain the inexplicable.

Now we jump ahead a hundred and ten years or so. It’s the late 1970s. I’m editing Package Engineering magazine at the time, and monitoring the food scientists who are experimenting to find a plastic container that will safely hold carbonated beverages, like pop and beer. Acrylonitrile (don’t count on my spelling) was the great white hope, as I recall.

But there was a controversy over free monomers, and the possibility of them migrating into the drinks---in which case they would, by FDA definition, have been either contaminants or adulterants.

Mind you, nobody was really sure whether 1. free monomers actually existed, or, if they did, 2. whether they migrated into the contents. But, by gawd, we’re from the gubmint, and we’ve got to protect everyone from dangers real or imagined. It reached the point where Congress was conducting hearings on the subject.

Called as a witness was Dr. Gilbert, whose first name escapes me at the moment. Dr. Gilbert was high up in (maybe even headed) the food science department at Rutgers University.

In front of God, a packed visitors balcony, and the entire Ooo Ess Congress, Dr. Gilbert first explains Maxwell's Demons theory, then maintains that even if there are free monomers produced they cannot migrate into the contents because Maxwell’s Demons will stop them at the gates.

Goodness gracious! Can you imagine! Congresses Dignity, with a capital D, would be put in jeopardy if word ever got out that they listened to a witness talk, straight facedly, about ******* control of a scientific question.

So, next morning, the Congressional Record (which is most emphatically not a true record, because anything that goes into it can (and most often is) edited and revised by any congressmen who wishes to do so), reported not on Maxwell’s Demons, but on a phenomenon it called “the Gilbert effect,” in which migration was a one-way street.

Phewwwww! I warned you it was a long, boring tale.

And if anyone, God forbid, really wants to know about James Maxwell and his demons, just google "maxwell's demons." But don't blame me if you do.

[KYHeirloomer]

why the system let the word de-mon appear half the time and edited it out the other half. Ditto the use of dem-onic.

If anyone needed more proof that Maxwell was right.......

[Luc_H]

Hey KYH,

are you saying de-mon was replace with ***** in your post?
Luc

[phatch]

You've got osmosis wrong. Water moves from low concentration to high concentration in the case of salt water and other osmosis situations. This works to equalize the salt concentration by diluting the high concentration while concentrating the plain waters salt.

Hot and cold water wouldn't osmose. There is no osmotic pressure in that case, rather convexion and conduction equalize temperatures.

It's the water that moves, not the salt. Same for other osmosis systems.

Phil

[Luc_H]

Hey KYH,

we asked for it and you delivered....

Patch is right about osmosis: Only water travels thru a membrane to dilute the more concentrated salted water.

If you take a U-shaped pipe with a water permeable/salt impermaeble membrane at the bottom, Fill one side with pure water and the other with salted water. The column of pure water will drop and the column of salted water will rise. The height difference is the osmotic pressure (or force).

Hot water/cold water columns in this device will stay in equilibrium height wise so no osmotic pressure present.

Great story nonetheless about how Congress solve the embarrassing conclusion of the proceedings i.e. de-mons control chemical migrations in plastic by inventing a scientific effect that suits their purpose. The Gilbert effect is one sided only....
Typical!

Luc

[deltadoc]

Originally Posted by phatch

You've got osmosis wrong. Water moves from low concentration to high concentration in the case of salt water and other osmosis situations. This works to equalize the salt concentration by diluting the high concentration while concentrating the plain waters salt.

Hot and cold water wouldn't osmose. There is no osmotic pressure in that case, rather convexion and conduction equalize temperatures.

It's the water that moves, not the salt. Same for other osmosis systems.

Phil

While its been a while since I got my BP (Bachelor of Physics) I think that there are some errors in both explanations.

One, salt is an ionic molecule only when it is not in solution. Once in solution, it "ionizes" into 1 Na+ plus 1 Cl- and is no longer a "molecule". Since a water molecule is considered "bipolar" the two H+ are about 120 degrees apart, and therefore cause the Oxygen atom to appear as the "--" pole of the bipolar water molecue (as the Oxygen atom has 2 extra electron positions in its outer shell). The Na+ ions are attracted to the double negative side (the oxygen side) of a water molecule, while the Cl- ions are attracted to the + side (two hydrogens) side of the water molecule.

Two, if it were true that "only the water moves, not the salt", then assuming you have a closed system divided in half by the semi-permeable membrane, then eventually one side would contain "nothing" because all the water migrated to the salty side (or conversely, all the water would migrate to the water side, and eventually only dry salt molecules would be left on one side of the semi-permeable membrane). This can't possibly happen because of entropy. Entropy is the desire of all "things arranged in order" to "disorganize". (this same principle explains why old buildings crumble, the universe is not static, and time moves in only one direction).

Luc H's example showed an "ordered" situation where the salty water was "organized" on one side of a permeable membrane and "non-salty" water on the other side. Yes, the ion's of salt, which are attached through ionic attraction to the bi-polar nature of a water molecule would move through the semi-permeable membrane along with the water molecule to which they have become attached. Due to pressure concerns, an "unsalty" water molecule would be forced to move in the opposite direction to attempt to maintain equilibrium.

Given enough time, both volumes on either side of the semi-permeable membrane would be equal in ionized salt content. (This, of course, assumes that the salt content is not "over saturated" such that salt molecules exist in such great numbers that they "clog" the membrane).

Also, on another note, the hot water/cold water isn't quite accurate either. yes convection/conduction play a role, but simply by being "hot"water, the hot water molecules have a higher energy state, and are bouncing around much more actively than the cold water molecules. That higher energy will force some of the hot water through the semi-permeable membrane in order to equalize pressure. That is the same principle that makes a closed system eventually explode as it is heated, unless there is a way to remove the pressure.

Anyway, back to plastic containers. Many plastics, especiallly polyvinylchloride (PVC) contain plasticizers known as Phthalates. These phthalates are securely entrenched in the food chain. They're everywhere, and we got lots of 'em in our bodies right now.

doc

[Luc_H]

Originally Posted by deltadoc

Two, if it were true that "only the water moves, not the salt", then assuming you have a closed system divided in half by the semi-permeable membrane, then eventually one side would contain "nothing" because all the water migrated to the salty side (or conversely, all the water would migrate to the water side, and eventually only dry salt molecules would be left on one side of the semi-permeable membrane). This can't possibly happen because of entropy.
doc

Osmotic pressure will prevent too much water from going to one side and drying the other. the combination of the differential salt concentration across the membrane and column height will hit an equilibrium in a close system (evaporation is eliminated). Entropy applies to the water movement across the membrane that is impeded on one side because of the salt.
Osmosis explains how you can purify water by pushing it trough a membrane so that salts are retain and pure water is collected on the other side (reverse osmosis). The pressure needed to push the water through the osmosis column is higher then the osmotic pressure working in reverse.

Check out: Osmosis - Wikipedia, the free encyclopedia
under: basic explanation

Consider a permeable membrane, such as visking tubing, with apertures small enough to allow water (solvent) molecules, but not larger solute molecules, to pass through. When this membrane is immersed in liquid it is constantly hit by molecules of the liquid, in motion due to their thermal kinetic energy. In this respect solute and solvent molecules are indistinguishable. At a molecular scale, every time a molecule hits the membrane it has a defined likelihood of passing through. Here, there is a difference: for water molecules this probability is non-zero; for solute molecules it is zero.
Suppose the membrane is in a volume of pure water. In this case, since the circumstances on both sides of the membrane are equivalent, water molecules pass in each direction at the same rate; there is no net flow of water through the membrane.
If there is a solution on one side, and pure water on the other, the membrane is still hit by molecules from both sides at the same rate. However, some of the molecules hitting the membrane from the solution side will be solute molecules, and these will not pass through the membrane. So water molecules pass through the membrane from this side at a slower rate. This will result in a net flow of water to the side with the solution. Assuming the membrane does not break, this net flow will slow and finally stop as the pressure on the solution side becomes such that the movement in each direction is equal: dynamic equilibrium. This could either be due to the water potential on both sides of the membrane being the same, or due to osmosis being inhibited by factors such as pressure potential or Osmotic pressure.

Entropy is the only <force> that explains how hot and cold water blend without agitation or other exterior force through a membrane because the water flows freely. For every molecule of water going through the membrane in one direction, hot or cold, one goes in the other direction. No column height difference, no osmotic pressure.

Deltadoc:....<These phthalates are securely entrenched in the food chain. They're everywhere, and we got lots of 'em in our bodies right now>
And also entrenched in the environment!

Luc